Synthesis of TiO2 and CuO-SnO2 nanofibers by · Synthesis of TiO2 and CuO-SnO2 nanofibers by electrospinning and their gas sensing properties 2011年 2月仁荷大學校大學院

工學碩士學位論文

전기방사를 이용한 TiO2 와 CuO-SnO2 나노섬유의

합성 및 가스 감응 특성

Synthesis of TiO2 and CuO-SnO2 nanofibers by

electrospinning and their gas sensing properties

2011 年 2 月

仁荷大學校大學院

金屬工學科

張進

2011 年 2 月

指導敎授金相燮

이 論文을 碩士學位論文으로 提出함

金屬工學科

張進

이 論文을 張進의 碩士學位論文으로 認定함

2011 年 2 月

主審 김현우

副審 김상섭

委員 김형순

Abstract

In recent years one dimensional (1D) nanostructrued materials such as

nanowires nanofibers nanorods and nanotubes have been an interesting

subject due to their importance both in fundamental studies and in

technological applications In particular the use of 1D nanostructured

materials is considered in photocatalysts chemical sensors solar cells and

batteries due to their unique properties Among the applications chemical

sensors are increasingly needed for safety environmental monitoring and

process control Because of this situation lots of researches have been

undertaken to enhance the chemical sensing properties Electrospinning is a

simple method to synthesize polymer and ceramic nanofibers By modifying

the electrospinning setup different shaped nanofibers such as hollow

nanofibers and heterostructured nanofibers can be obtained In present study

hollow TiO2 nanofibers were synthesized via coaxial electropsinning In

addition CuO-SnO2 nanofibers were synthesized via a ldquodouble-needlerdquo

electrospinning These nanofibers were characterized by scanning electron

microscopy and X-ray diffraction The synthesized nanofibers were

distributed uniformly on the silicon substrate and had a polycrystalline nature

Importantly depending on the viscosity of the electrospinning solution the

diameter and wall thickness of the hollow TiO2 fibers were systematically

changed in the range of micro to nano scale The sensors based on these

nanofibers exhibited good sensitivity and dynamic properties for tested gases

In particular CuO-SnO2 heterostructured nanofibers synthesized using

ldquodouble needlerdquo electrospinning show extremely high sensitivity and

extremely fast response to H2S The result in this study demonstrated that

hollow nanofibers and heterostructured nanofibers hold promise for realization

of sensitive and reliable chemical gas sensors

Content Abstract i

Content iii

List of figures iv

1 Introduction 1

2 Background 4

21 Synthesis of oxide nanofibers by electrospinning 4

211 Solid nanofibers 4

212 Core-shell nanofibers 10

213 Hollow nanofibers 14

214 Aligned nanofibers 18

22 Gas sensing based on electrospun metal oxide nanofibers 23

221 Background knowledge of gas sensors 23

222 Literature survey 23

3 Experiment 36

31 Synthesis of hollow TiO2 nanofibers 36

32 Synthesis of CuO-SnO2 heterostructured nanofibers 38

33 Characterization 41

4 Results and Discussion 42

41 Hollow TiO2 nanofibers 42

42 CuO-SnO2 heterostructured nanofibers 52

421 Nanofibers synthesized by single-needle electrospinning 52

422 Nanofibers synthesized by double-needle electrospinning 60

5 Conclusion 70

List of figures

Figure 1 Schematic illustration of the conventional basic set-up for

electrospinning

Figure 2 (a) SEM image of TiO2PVP nanofibers that were electrospun from

an ethanol solution containing Ti(OiPr)4 (01 gmL) and PVP (003

gmL) The electric field strength was 1 kVcm (b) SEM image of

the same sample after it had been calcined in air at 500 oC for 3 h

(c) Histogram showing the size distribution of nanofibers

contained in the calcined sample (d) XRD pattern of the same

calcined sample All diffraction peaks can be indexed to those of

the anatase phase of titania

Figure 3 Scanning electron microscopy images of ZnO fibers (a) zinc

acetatepolyvinyl alcohol composite fibers with 50 wt of zinc

acetate (b) calcined at 500 oC for 6 h (c) calcined at 500 oC for 8 h

and (d) calcined at 500 oC for 10 h (e) Diameter of ZnO fibers as a

function of calcination time

Figure 4 (a) Experiment setup used for co-electrospinning of compound

core-shell nanofibers (b) TEM of a compound nanofibers Core

and shell solutions are PSU and PEO respectively (c) TEM of

unstained samples of co-electrospun PEO (core) and PDT (shell)

(d) TEM of annealed (170 oC 2 h) unstained samples of

co-electrospun PLA and Pd(OAc)2

Figure 5 Typical FE-SEM images of SnO2ndashZnO corendashshell nanofibers

prepared with different ALD cycles of (a) 0 (b) 50 (c) 100 (d)

200 (e) 300 and (f) 400 Note that (a) represents SnO2 core

nanofibers without ZnO shell layers (g) ZnO shell thickness in the

corendashshell nanofibers as a function of ALD cycles The slope

indicates the growth rate of ZnO shell layers

Figure 6 (a) Conception for preparation of hollow nanofibers (b) SEM

micrograph with edge-on view of a layered arrangement of PPX

tubes (c) SEM showing the inner surface of PPX tubes (d) SEM

of aluminum tubes prepared by coating electrospun PLA fibers

with aluminum followed by thermally induced degradation of the

template fibers

Figure 7 (a) Schematic illustration of the setup for electrospinning nanofibers

having a coresheath structure (b) TEM image of two as-spun

hollow fibers after the oily cores had been extracted with octane (c)

TEM image of TiO2 (anatase) hollow fibers that were obtained by

calcining the composite nanotubes in air at 500 oC (d) SEM image

of a uniaxially aligned array of anatase hollow fibers that were

collected across the gap between a pair of electrodes In the

preparation of all these samples the feeding rate for heavy mineral

oil was 01 mLh and the concentrations of Ti(OiPr)4 and PVP

were 03 and 003 gmL respectively The voltage of

electrospinning was 12 kV

Figure 8 (a) Schematic illustration of the setup for electrospinning that we

used to generate uniaxially aligned nanofibers The collector

contained two pieces of conductive silicon stripes separated by a

gap (b) Calculated electric field strength vectors in the region

between the needle and the collector The arrows denote the

direction of the electrostatic field lines (c) Electrostatic force

analysis of a charged nanofiber spanning across the gap

Figure 9 (a) Plexiglas disk with copper wires Electrospun nylon nanofibers

are collected on the copper wires The nanofiber mat shows

stratified layering in the magnified image (b) Apparatus for

rotating the copper wire drum during electrospinning SEM

images of axially aligned polymer nanofibers on conductive

copper wire drum (c d and e) alignment after 5 min of spinning

time (f g) after 15 min (h i and j) after 40 min and (k) after 25 h

of spinning time

Figure 10 (a) SEM image of the as-spun TiO2PVAc composite fibers

fabricated by electrospinning (b) SEM image of TiO2PVAc

composite fibers after hot pressing at 120 oC for 10 min (c) SEM

image of unpressed TiO2 nanofibers after calcination at 450 oC (d)

SEM image of hot pressed TiO2 nanofibers after calcinations at

450 oC (e) The resistance response during cyclic exposure to 10

min pulses with increasing concentrations of NO2 mixed in dry air

at various operating temperatures (b) Sensitivity versus

temperature histogram upon exposure to 500 ppb NO2 in dry air

Figure 11 (a) SEM image of the precursors (b) ZnO nanofibers prepared by

calcination of the precursors at 600 oC for 5 h (c) TEM image of

pure ZnO nanofibers The inset in (c) is SAED pattern of the

product (d) XRD pattern of the products(e) Response transients

of the sensor to ethanol changing from 10 to 1000 ppm (f) Cross

sensitivity of the sensor to various gases

Figure 12 (a b c) SEM images of SnO2 nanofibers with different

magnifications (d) Response of the sensor to 200 ppm ethanol as a

function of operating temperature (e) Responserecovery curves

of the sensor to ethanol in the range of 001ndash5000 ppm at 330 oC (f)

Response of the sensor as a function of ethanol concentration at

330 oC

Figure 13 (a) Dynamic response of the SnO2ndashZnO corendashshell nanofiber

sensor to O2 The inset is the enlarged part of the data obtained at

300 ppm O2 (b) The variation of sensitivity as a function of O2

concentration (c) Dynamic response of the ZnO nanofiber sensor

to O2 The inset is the enlarged part of the data obtained at 300 ppm

O2 (d) The variation of sensitivity of the ZnO nanofiber sensor as

a function of O2 (e) Dynamic response of the SnO2ndashZnO

corendashshell nanofiber sensor to NO2 The inset is the enlarged part

of the data obtained at 1 ppm NO2 (f) The variation of sensitivity

as a function of NO2 concentration concentration

Figure 14 SEM images of (a) m-ZndashS nanofibers (b) ZndashS nanofibers The

insets are TEM images and nitrogen adsorptionndashdesorption

isotherms of m-ZndashS nanofibers (c) Four cycles of

responsendashrecovery characteristics of m-ZndashS nanofibers exposed to

different ethanol concentrations (d) Sensitivity versus ethanol

concentration in the range 5ndash10000 ppm (e) Sketch of chemical

sensing of mesoporous ZndashS nanofibers

Figure 15 SEM images of (a) the pristine ZnO nanofibers and (b) the

SnO2-ZnO hybrid nanofibers The images of (c) bright-field

STEM and (d) elemental mapping of Zn (red) and Sn (green) for a

SnO2-ZnO hybrid nanofiber of 72 nm in diameter (e) NO2

responses of the SnO2-ZnO hybrid nanofibers-based sensor as a

function of working temperature (f) The comparison of NO2

responses for gas sensor based on the pristine ZnO nanofibers

(blue) and the SnO2-ZnO hybrid nanofibers (red) as a function of

gas concentration

Figure 16 Schematic illustration of the electrospinning technique with a

core-shell needle used in this study

Figure 17 Schematic illustration of the ldquodouble-needlerdquo electrospinning

technique

Figure 18 SEM images of as-spun hollow fibers with different PVP

concentrations (a) 004 (b) 006 (c) 008 and (d) 01 gml

Figure 19 (a) Change in the viscosity of the solutions as a function of PVP

concentration (b) Change in the diameter of the as-spun hollow

fibers as a function of the viscosity of the solutions

Figure 20 Change in the diameter of as-spun hollow fibers as a function of the

viscosity of the solution (log-log plot) For comparison the result

of ZnO and YBa2Cu3O7- δ are included

Figure 21 SEM image of TiO2 hollow fibers obtained after calcination at 600

oC for 2 h with different PVP concentration (a) 004 (b) 006 (c)

008 and (d) 01 gml The insets are low-magnified SEM images

revealing the corresponding overall morphologies of the fibers

Figure 22 Typical XRD pattern obtained from hollow TiO2 fibers synthesized

from the solution with a PVP concentration of 004 gml

Figure 23 Change in diameter of hollow TiO2 fibers after calcination as a

function of the viscosity of the solutions

Figure 24 Dynamic response at various CO concentrations for the sensor

fabricated from the hollow TiO2 fibers whose average diameter

was 200 nm

Figure 25 Typical SEM image of heterostructured CuO-SnO2 nanofibers (a)

as-spun (b) calcined at 700 oC

Figure 26 SEM image of heterostructured CuO-SnO2 nanofibers (a) x=0 (b)

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

Figure 27 Typical XRD pattern obtained from various CuO-SnO2 nanofibers

contained different CuO content

Figure 28 Dynamic response at various H2S and CO gas concentrations for

the sensor fabricated from two selected CuO-SnO2 nanofibers (a c)

x=001 (b d) x=01

Figure 29 Sensitivity of the sensors fabricated from two selected CuO-SnO2

nanofibers as function of H2S gas concentration

Figure 30 Dynamic response of bare SnO2 nanofiber sensor at (a) 100 oC (b)

300 oC

Figure 31 SEM image of typical heterostructured CuO-SnO2 nanofibers

synthesized via ldquodouble needlerdquo electrospinning (a) as-spun (b)

calcined at 700 oC

Figure 32 Typical XRD pattern obtained from heterostructured CuO-SnO2

nanofibers synthesized via ldquodouble-needlerdquo electrospinning

Figure 33 Dynamic response at various H2S concentrations and temperature

(a) 300 oC (b) 250 oC (c) 200 oC for the sensor fabricated from

heterostructured CuO-SnO2 nanofibers synthesized via

ldquodouble-needlerdquo electrospinning

Figure 34 Sensitivity of the sensors fabricated from heterostructured

CuO-SnO2 nanofibers as function of H2S gas concentration at

various temperature

Figure 35 The response and recovery time of CuO-SnO2 heterostructured

nanofiber sensor at various temperatures

Figure 36 (a) Band diagram of CuO-SnO2 (b) band diagram of CuS-SnO2

1 Introduction

In the past decade nanosized materials have been a subject of intense

research owing to their unique properties In particular one-dimensional (1D)

nanostructured metal oxides have attracted interest due to their potential

applications in many areas of technology such as optics photonics electronics

and biology Among different shapes of 1D nanostructured materials hollow

nanofibers and heterostructured nanofibers are expected to hold promise

application in chemical sensing due to their unique physical and chemical

properties For example hollow nanofibers have inner and outer surfaces

meaning that the surface to volume ratio almost doubles compared with

normal solid nanofibers This feature allows them to have good sensing

properties In case of heterostructured nanofibers the formation and disruption

of p-n junction leads to a good sensitivity and selectivity to specific gases

Electrospinning is a simple and versatile method to synthesize nanofibers

of various materials such as polymers ceramics and their composites In most

cases it has been employed to synthesize uniform dense nanofibers [1-3] By

modifying the electrospinning different shaped nanofibers can be obtained

For example by using a core-shell needle various metal oxide have been

successfully synthesized [4-7]

To the best of our knowledge no study has been undertaken on the control

of the diameter of hollow oxide fibers by coaxial electrospinning in spite of

the importance of this aspect in their practical applications In this work

hollow TiO2 fibers were synthesized via an electrospinning technique with a

core-shell needle The diameters of the fibers were controlled from nano- to

micro-scale by changing the viscosity of the precursor solutions A simple

mathematical expression is proposed to explain the change in diameter of the

hollow TiO2 fibers Besides this we presented a novel ldquotwo-syringes rdquo

electrospinning to synthesized CuO-SnO2 heterostructured nanofibers In

addition to test their potential use in chemical gas sensors their gas sensing

properties were investigated

Reference

[1] J Y Park S S Kim J Am Ceram Soc 92 (2009) 1691

[2] S W Choi J Y Park S S Kim Nanotechnology 20 (2009) 465603

[3] J Y Park S W Choi K Asokan S S Kim J Nanosci Nanotechnol 10

(2010) 3604

[4] S Zhan D Chen X Jiao C Tao J Phys Chem B 110 (2006) 11199

[5] S Zhan D Chen X Jiao S Liu J Colloid Interf Sci 308 (2007) 265

[6] S Zhan Y Li H Yu J Disper Sci Technol 29 (2008) 702

[7] J E Panels Y L Joo J Nanomater 2006 (2006) 1

2 Background

21 Synthesis of oxide nanofibers by electrospinning

Recent years one dimensional (1D) nanostructures such as nanowires

nanorods nanotubes nanofibers have become the focus of intensive research

due to their potential applications in lots of areas of technology such as optics

photonics electronics and biology In particular for gas sensor application 1D

oxide nanostructures usually show better performance compare with thin-film

and bulk sensors because of their enhanced surface to volume ratio which

allows very sensitive transduction of the gassurface interaction into a change

of the electrical conductivity [1]

Electrospinning is simple and versatile technique that fabricates

nanofibers an important 1D nanostrucre through an electrically charged jet of

polymer solution Though it is usually used to synthesize solid nanofibers by

modifying the electrospinning set-up different shaped nanofibers could be

synthesized In this section we summarize the current research of different

shaped nanofibers including solid nanofibers core-shell nanofibers hollow

nanofibers and aligned nanofibers synthesized by electospinning technique

211 Solid nanofibers

Figure 1 shows a schematic illustration of the conventional basic set-up

for electrospinning It consists of three major components a high-voltage

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

Li and co-workers prepared TiO2 nanofibers via this simple technique

using polyvinyl pyrrolidone (PVP) and titanium tetraisopropoxide as

precusors In a typical procedure 15 g of titanium tetraisopropoxide was

mixed with 3 ml of acetic acid and 3 ml of ethanol in a glovebox Acetic acid

here can stabilize the solution and control the hydrolysis reactions of the

precursors After 10 min this solution was removed from the glovebox and

added to 75 ml of ethanol that contained 045 g of PVP followed by magnetic

stirring for 1 h The elctrospinning conditions like voltage and feeding rate

were adjusted during the electrospinning process After electrospinning the

as-spun nanofibers were left in air for 5 h to allow the hydrolysis of titanium

tetraisopropoxide to go to completion Finally the PVP was selectively

removed from these nanofibers by treating them in air at 500 oC for 3 h As

shown in Figure 2 they demonstrate that the thickness of TiO2 nanofibers

could be varied by controlling a number of electrospinning parameters such as

PVP concentration and feeding rate The nanofibers increased from 33 to 192

nm in diameter as the PVP concentration was increased The feeding rate of

the solution also influenced the diameter of the fibers Faster feeding rates

often resulted in thicker fibers but the jets became unstable if the feeding rate

exceeded 05 mlh [2]

Wu and co-workers used polyvinyl acetate (PVA) and zinc acetate as

precursors to prepare ZnO nanofibers An aqueous PVA solution was first

prepared by dissolving PVA in deionized water and heating at 70 oC with

vigorous stirring for 1 h and zinc acetate was then added to the solution After

churning for 5 h at room temperature a viscous zinc acetatePVA solution was

load to the syringe The distance between the collector and the needle tip was

20 cm The applied voltage and feeding rate were 20 kV and 1mlh

respectively The as-spun fibers were dried at 120 oC for 1 h and then calcined

at 500 oC in air As shown in Figure 3 the as-spun fibers have a smooth surface

and uniform diameter along the whole length After calcinantion the diameter

of the fibers decreased obviously In their research they presented an equation

to explain the relationship between the average diameter of ZnO nanofibers

and the concentration of zinc acetate in the elctrospinning solution

D=kC+d0

where C is the zinc acetate concentration k is a constant coefficient and d0

represents the average diameter of pure PVA electrospun nanofibers For their

electrospinning conditions k=00667 d0=300 (nm) In addition the diameters

of ZnO nanofibers were changing from 400 nm to 100 nm as a function of

calcination time [3]

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

212 Core-shell nanofibers

By modifying the conventional electrospinning setup core-shell

nanofibers could be synthesized by electrospinning

Sun and co-workers prepared compound core-shell polymer nanofibers by

ldquoco-electrospinningrdquo As shown in Figure 4 the setup they used in

co-electrospinning is similar to the conventional one except for the core-shell

needle The idea of core-shell needle was first presented by I G Loscertales

and co-workers in 2002 They used a core-shell needle in the electrospray

system to fabricate monodisperse capsules with diameters varying between 10

and 015 micrometers depending on the running parameters Z Sun and

co-workers employed this core-shell needle to the elctrospinning technique

and succeeded in preparing different core-shell materials system compound

nanofibers including polysulfone (PSU)-polyethylene oxide (PEO) and

polydodecylthiophene (PDT)-PEO Interestingly the PDT used in their

experiment did not form fibers by itself in elctrospinning due to its low

molecular weight They demonstrated the PEO shell served as a template for

the formation of the PDT fibers [4]

Choi and co-workers prepared SnO2-ZnO core-shell nanofibers via a

novel two-step process including electrospinning and atomic layer deposition

(ALD) First SnO2 nanofibers were prepared by electropsinning technique

using tin (II) chloride and polyvinyl acetate (PVAc) as precursors For forming

the shell structure ZnO was deposited on the synthesized SnO2 nanofibers by

ALD technique using H2O and diethylzinc as precusors As shown in Figure 5

the ZnO shell layers uniformly cover the surface of the core SnO2 nanofibers

and appear grainy As the ALD cycle increases the diameter of corendashshell

nanofibers increases progressively The XRD patterns indicated the formation

of ZnO after ALD [5]

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

213 Hollow nanofibers

Similar to core-shell nanofibers there are two ways to synthesize hollow

nanofibers by electrospinning template method and coaxial electrospinning

Bognitzki and co-workers succeeded in preparing the hollow polymer

metal and polymermetal hybrid fibers by a template two-step method First

they prepared poly L-lactide (PLA) fibers as a template by electrospinning

They choose PLA as template because of its low melting point (215 oC) which

is the most important factor in template technique As shown in Figure 6 they

coated various materials on the templates and removed the templates by

annealing In the case of fabricating polymer tubes they coated the PLA fibers

by chemical vapor deposition (CVD) with poly p-xylylene (PPX) Subsequent

annealing of these fibers above 250 oC under vacuum resulted in the

degradation of the PLA core which leaded to PPX tubes Similarly aluminum

tubes were fabricated by coating the PLA core by physical vapor deposition

(PVD) and removal the cores by annealing By this template technique

various materials system of hollow fibers could be synthesized but the

inconvenience of two-step coating prevents its wide use [6]

After Loscertales and co-workers first reported the idea of core-shell

needle a number of groups attempted to synthesize hollow fibers by one-step

method

Li and co-workers reported the first successful synthesis of hollow TiO2

nanofibers of 200 to 500 nm in diameter using coaxial electrospinning As we

mentioned in the former section a coaxial needle was used in the

electrospinning setup They used heavy mineral oil as the core material and

titanium tetraisopropoxidePVP as the shell precursors The heavy mineral oil

cannot form fibers itself by electrospinning thus the shell polymer solution

served as template for the core solution which is a quite common phenomenon

in coaxial electropsinning The as-spun nanofibers was immersed in octane

overnight to extract the heavy mineral oil Pure hollow TiO2 nanofibers were

obtained by calcining these nanofibers in air at 500 oC for 1 h [7]

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

214 Aligned nanofibers

By modifying the collector of electospinning aligned nanofibers can be

generated Usually there are two method to synthesize aligned nanofibers

One is to use a parallel conducting collector another is to use a rotating

collector

Li and co-workers reported a simple and versatile method that generated

uniaxially aligned nanofibers over large areas by introducing a gap into the

conventional collector As assisted by electrostatic interactions the nanofibers

were stretched across the gap to form a parallel array As shown in Figure 8

the collector contained a gap in its middle Such a collector could be simply

fabricated by putting two stripes of electrical conductors together or by cutting

a piece of aluminum foil The width of the gap could be varied from hundreds

of micrometers to several centimeters Unlike the conventional system the

electric field lines in the vicinity of the collector were split into two fractions

pointing toward opposite edges of the gap The as-spun fiber can be considered

to be a string of positively charged elements connected through a viscoelastic

medium In general the charged nanofiber should experience two sets of

electrostatic forces the first set (F1) originating from the splitting electric field

and the second one between the charged fiber and image charges induced on

the surfaces of the two grounded electrodes (F2) In particular electrostatic

force F1 should be in the same direction as the electric field lines and should

pull the two ends of the fiber toward the two electrodes Once the charged fiber

has moved into the vicinity of the electrodes charges on the fiber will induce

opposite charges on the surfaces of the electrodes Considering that Coulomb

interactions are inversely proportional to the square of the separation between

charges the two ends of the fiber closest to the electrodes should generate the

strongest electrostatic force (F2) which will stretch the nanofiber across the

gap to have it positioned perpendicular to the edge of the electrode In addition

unlike fibers directly deposited on top of an electrode where they can be

immediately discharged the fibers suspended across the gap can remain highly

charged after deposition The electrostatic repulsion between the deposited

and the upcoming fibers can further enhance the parallel alignment (because it

represents the lowest energy configuration for an array system of highly

charged fibers) Base on this setup and mechanism they succeeded in

fabricating various of aligned nanofibers such as PVP nanofibers carbon

nanofibers and TiO2 nanofibers [8]

Another basic form of getting aligned nanofibers is through the use of

rotating mandrel This is a simple mechanical method of aligning the fibers

along the circumference of the mandrel As the fibers are formed from the

electrospinning jet the mandrel that is used to collect the fibers is rotated at

very high speed up to thousands of rpm Katta and co-workers used a ratating

wired drum to collect aligned electrospun nanofibers The drum has two

circular nonconducting Plexiglas disks 127 cm in diameter with a 12 cm

diameter hole cut in the center Each disk has 6 mm deep saw cut notches

placed one centimeter apart around the circumference The two disks are

mounted on a rod and spaced 30 cm apart with PVC pipe The copper wire is

stretched between the slots cut into the edges of the disks shown in Figure 9

The rotation speed of the drum was reported to be 1 rpm By using this

collector they synthesized aligned nylon-6 nanofibers [9]

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

22 Gas sensing based on electrospun metal oxide nanofibers

221 Background knowledge of gas sensors

Metal oxide semiconductors are usually wide band gap that are insulating

in which the semiconducting behavior results from a deviation of

stoichiometry The semiconducting nature of metal oxide semiconductors

makes it possible for electrical conductivity of material to change when the

composition of surrounding atmosphere changes At the suitable temperature

in air charged species such as O2- O- and O2- are adsorbed on the metal oxide

charging it negative If a reducing species such as CO is present it is oxidized

by the charged species which increases the conductivity of the material The

reaction formula can be written as follow

CO+O-rarrCO+e-

CO+2O- rarrCO32- rarrCO2+12O2+2e-

In the presence of an electronegative species such as NO2 the charges are

attracted to the adsorbed molecule which decrease the conductivity of

material the reaction formula is like this

NO2+e- rarrNO2-

222 Literature survey

1) Single phase nanofibers

Kim and co-workers synthesized TiO2 nanofibers by electrospinning and

investigated its NO2 sensing properties In their study In this study

TiO2PVAc composite nanofiber mats were directly electrospun onto

interdigitated Pt electrode arrays hot pressed at 120 degC and calcined at 450 degC

This resulted in a novel multiple nanowire network composed of sheaths of

200-500 nm diameter cores filled with readily gas accessible 10 nm thick

single-crystal anatase fibrils They demonstrated that the electrospun TiO2

nanofiber exhibited exceptional sensitivity to NO2 with a detection limit

estimated to be well below 1 ppb The markedly improved adhesion connected

with the hot pressing step significantly advances the viability of electrospun

nanofiber sensor [10]

Wang and co-workers synthesized ZnO nanofibers by electrospinning and

tested its ethanol sensing properties ZnO nanofibers were fabricated through

electrospinning by using zinc acetate and PVA as presursors The

electrospinning experiment is almost the same as we described in the former

sections They demonstrated that the as-prepared sensor based on ZnO

nanofibers is highly sensitive to ethanol at 300 oC with response and recovery

times of about 3 and 8 s respectively The excellent sensitivity is based on the

mechanism that ZnO nanofiber gas sensors respond to the change in the carrier

concentration [11]

Zhang and co-workers fabricated the SnO2 nanofibers by electrospinning

by using tin(IV) chloride and PVA as precursors and tested its ethanol sensing

properties Gas sensing properties were measured using a static test system

which included a test chamber and a data acquisitionprocessing system Dry

synthetic air was used as both a reference gas and a diluting gas to obtain

desired concentrations of ethanol Saturated ethanol vapor was injected into

the test chamber by a syringe through a rubber plug After fully mixed with the

diluting gas the sensor was put into the test chamber When the response

reached a constant value the sensor was taken out to recover in dry air When

the sensor was operated at 330 C it exhibited a large response to 10 ppm

ethanol (sim45) low detection limit (lt10 ppb) fast responserecovery (lt14 s)

and good reproducibility [12]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

overy curveoC (f) Res

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

2) Heterostructured nanofibers

Choi and co-workers reported the O2 and NO2 sensing properties of

SnO2-ZnO core-shell nanofibers synthesized by a novel two step method

Synthesis of SnO2-ZnO core-shell nanofibers have already been described in

the former section They demonstrated that chemical sensor based on

SnO2-ZnO naofibers had high sensitivity and dynamic repeatability to O2 and

NO2 gas A combination of homoandhetero-interfaces formed at the junctions

in the corendash shell nanofiber sensor may be the reason for the improved

sensitivity compared with the sensor based on the nanofiber without a shell

layer [5]

Song and co-workers reported that a simply and versatile method for the

large-scale synthesis of sensitive mesoporous ZnO-SnO2 nanofibers through a

combination of surfactant-directed assmembly and an electrospinning

approach and fabricated the sensor of ZnO-SnO2 nanofibers to ethanol

According to the analysis an mesoporous structure was observed in these

nanofibers The moreenhanced sensing properties such as high sensiticity

quick response reproducibility and linear dependence of the sensitivity of the

nanofibers sensor may be attributed to the surface-depletion effect to ethanol

gas due to both the mesoporous structure and the ZnO-SnO2 heterojuction

Park and co-workers prepared SnO2-ZnO hybrid nanofibers that were

synthesized via a novel two-step process First ZnO nanofibers were

synthesized on Pt-interdigital electodeSiO2Si substrate by electrospinning

The electrospun ZnOPVP composite fibers were hot-pressed Subsequently

the composite fibers were baked on a hotplate to remove the solvent

Thereafter the ZnOPVP composite fibers were calcined at 600 oC for 1h to

remove PVP and crystallize the ZnO In sequence SnO2 thin layer were

depostited using pulsed laser deposition (PLD) methods on the synthesized

ZnO nanofibers SnO2-ZnO hybrid nanofibers with a random network

structure were obtained They demonstrated a method to electrochemically

functionalization ZnO nanofibers by surface modification by deposition SnO2

thin layer to improve the gas response of ZnO nanofibers to low NO2

concentration The enhanced sensitivity may be attributed to the change in

resistance due to both the extra adsorption by hetero-materials coating layer

and the charge transfer occurring between hetero-materials [14]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[1] R L Vander Wal G W Hunter J C Xu M J Kulis G M Berger T M

Ticich Sens Actuat B 138 (2009) 113

[2] D Li Y Xia Nano let 3 (2003) 555

[3] H Wu W Pan J Am Cer Soc 89 (2006) 699

[4] Z Sun E Zussman A L Yarin J H Wendorff A Greiner Adv Mater

15 (2003) 1929

[6] M Bognitzki H Hou M Ishaque T Frese M Hellwig C Schwarte A

Schaper J H Wendorff A Greiner Adv Mater 12 (2000) 9

[7] D Li Y Xia Nano lett 4 (2004) 933

[8] D Li Y Wang Y Xia Nano lett 3 (2003) 1167

[9] P Katta M Alessandro R D Ramsier G G Chase Nano lett 4 (2004)

[10] II-D Kim A Rothschild B H Lee D Y Kim S M Jo H L Tuller

Nano let 6 (2006) 2009

[11] W Wang H Huang Z Li H Zhang YWang W Zheng C Wang J

Am Ceram Soc 91 (2008) 3817

[12] Y Zhang X He J Li Z Miao F Huang Sens Actuat B 132 (2008) 67

[13] X Song Z Wang Y Liu C Wang L Li Nanotechnology 20 (2009)

075501

[14] J A Park J Moon S J Lee S H Kim H Y Chu T Zyung Sens

Actuat B 145 (2010) 592

3 Experiment

31 Synthesis of hollow TiO2 nanofibers

311 Experiment apparatus

Hollow TiO2 fibers were synthesized by electrospinning with a core-shell

needle As shown in Figure 16 the coaxial electrospinning set-up consists of a

high power supply a syringe pump an aluminum collector two syringes and

a core-shell needle It is basically the same as the conventional set-up except

for the core-shell needle

312 Solution preparation

The solutions for electrospinning were prepared as follows First a mixed

solvent consisting of 4 ml of acetic acid and 10 ml of ethanol was prepared

Different amounts (08 - 2 g) of polyvinylpyrrolidone (PVP Mwasymp1300000)

were dissolved in the mixed solvent while stirring for 2 h at room temperature

Subsequently 6 g of titanium isopropoxide was added to the PVP solutions

respectively while stirring for 6 h at room temperature In this experiment the

PVP concentration in the solutions was varied from 004 to 01 gml which

eventually changed the viscosity of the precursor solutions

313 Fabrication of hollow TiO2 fibers

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

32 Synthesis of CuO-SnO2 heterostructured nanofibers

321 Electrospinning apparatus

The CuO-SnO2 heterostructured nanofibers were synthesized via two

ways of electrospinning including conventional basic electrospinning and

novel ldquodouble-needlerdquo electrospinning The setup of basic electrospinning was

already described in section 211 in detail The ldquodouble-needlerdquo

electrospinning setup is shown in Figure 17 It consists of a high power supply

a syringe pump an aluminum collector two syringes and two needles It is

basically the same as the conventional set-up except for two syringes and two

needles

1) For single-needle electrospinning

SnCl2bull2H2O CuCl2bull2H2O and polyvinyl acetate (PVAc) were used as

precursors materials The electrospinning solutions were prepared as follow

First 154 g of PVAc was dissolved in a mixed solvent consisting 942 g of

DMF and 117 g of ethanol while stirring for 2 h at room temperature

Subsequently 1g of SnCl2bull2H2O and certain amount of CuCl2bull2H2O were

added into the PVAc solution Eight solutions were prepared on the this way

except of the different molar ratio of Cu and Sn The ratio of Cu and Sn was

written as xCuO-(1-x)SnO2 After stirring for 12 h at room temperature the

viscous electrospinning solutions were obtained

2) For double-needle electrospinning

In case of double-needle electrospinning CuO solution and SnO2 solution

were prepared individually The preparation method is almost the same as we

described above The CuO solution was a mixture of 01 g CuCl2bull2H2O 154 g

PVAc in 942 g DMF and 117 g ethanol while the SnO2 solution was a

mixture of 1 g CuCl2bull2H2O 154 g PVAc in 942 g DMF and 117 g ethanol

323 Fabrication of heterostructured CuO-SnO2 nanofibers

1) Single-needle electrospinning

In case of single-needle elextrospinning the prepared solutions of

CuCl2bull2H2O and SnCl2bull2H2O composite were loaded into a glass syringe

connected to a 21 gauge needle During the electrospinning process the

applied voltage was fixed at 20 kV and the feeding rate was fixed at 003 mlh

The silicon substrates placed on the aluminum collector were located 20 cm

away from the tip of the needle All the electrospinning experiments were

carried out at room temperature and air ambient By calcining the as-spun

nanofibers at 700 oC for 4 h crystalline heterostructured CuO-SnO2 fibers

were eventually synthesized

2) Double-needle electrospinning

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

The viscosity of solutions was measured at room temperature using a

viscometer (Brookfield Viscometer DV-II Pro) The microstructure and phase

were investigated using field-emission scanning electron microscopy

(FE-SEM HitachiS-4200) and X-ray diffraction (XRD PhilipsXpert MPD)

respectively For the gas sensing measurements Ni (~200 nm in thickness) and

Au (~50 nm) double layer electrodes were sequentially deposited via

sputtering on the specimens using an interdigital electrode mask The response

of these nanofibers was measured at room temperature using a home-made gas

dilution and sensing system

4 Results and Discussion

41 Hollow TiO2 nanofibers

Figure 18 shows the microstructures of as-spun hollow fibers obtained

after being immersed in octane for 12 h These as-prepared hollow fibers

should comprise a mixture of titanium isopropoixde and PVP as well as a

small amount of solvent As shown the microstructures of the fibers are the

same in nature regardless of the PVP concentration The semi-transparency of

each fiber reveals the hollow nature of the as-prepared fibers The diameter of

the fibers is quite uniform but varies depending on the content of PVP in the

electrospinning solution The variation in the concentration of PVP

consequently results in a corresponding change in the viscosity of the

electrospinning solution Figure 19(a) shows the change in viscosity as a

function of PVP concentration As expected the viscosity increases from 142

to 867 mPamiddots as the content of PVP in the precursor solution is increased

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

PVP concentration (gml)

200 400 600 8000

Viscosity of solutions (mPas)

concentration (b) Change in the diameter of the as-spun hollow fibers as a

In our electrospinning conditions variation of the processing parameters

such as the feeding rate and the applied voltage revealed no obvious effects on

the diameter of the hollow fibers However the viscosity of the solutions

played a key role in controlling the diameter of the hollow TiO2 fibers In

general the viscosity of a solution is related to the molecular weight and

concentration of polymers dissolved in the solvent In this study we varied the

concentration of the polymer to control the viscosity An increase in the

polymer concentration will typically in greater entanglement of polymer

chains This is the most likely reason to explain the increase in the viscosity of

the solutions Figure 19(b) shows the diameter of the as-spun hollow fibers

before calcination as a function of the viscosity of electrospinning solution A

higher viscosity produces hollow fibers with larger diameter in the as-spun

The diameter of normal solid nanofibers of polymers is known to be

related with the viscosity of electrospinning solutions following a power law

relationship [1-3] We propose a simple mathematical expression given as Eq

(1) to explain the relationship between the viscosity of the solutions and the

diameter of oxide fibers assuming that the diameter of the oxide fibers follows

the behavior of polymer fibers

D - D0 = kη (1)

where D is the diameter of the fibers at a certain viscosity of η D0 is the

diameter of the fibers when η approaches zero η is the viscosity of the solution

n is an exponent and k is a constant When η is zero the spinning solution

usually breaks into liquid droplets consequently generating nanoparticles

instead of nanofibers Thus it is reasonable to neglect D0 The plot of log D

versus log η shown in Figure 20 readily gives the value of n The slope n is

085 This power law relationship is quite common in electrospun polymers

[1-3] With increasing viscosity of the solution the increased viscoelasticity

usually prevents the jet segment from being stretched by the constant

Coulombic force resulting in fibers of greater diameter It is of note that the

as-spun hollow fibers exhibit similar behavior to electrospun synthesized

polymer fibers in terms of variation of diameter with viscosity In Fig 4 for

comparison previously reported data regarding viscosity of solutions and the

diameter of as-spun fibers of YBa2Cu3O7-δ [4] and ZnO [5] are replotted in a

log D-log η scheme The linear relationships in the log D-log η plots

demonstrate the validity of Eq (1) which can be generally used to describe the

change in diameter of electrospun ceramic nano or microfibers

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

viscosity of the solution (log-log plot) For comparison the result of ZnO and

YBa2Cu3O7- δ are included

For the purpose of obtaining hollow fibers of pure TiO2 phase the as-spun

hollow fibers were calcined at 600 oC for 2 h under an air atmosphere Figure

21 shows typical SEM images taken from the hollow TiO2 fibers after

calcination It is obvious that the fibers are hollow The inset figures reveal

their overall microstructures After calcination the walls of the hollow TiO2

fibers are smooth and have uniform thickness of ~ 90 nm The images

displayed in Figure 21 also suggest that the oil phase was encapsulated as a

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

Figure 23 shows the diameters of hollow TiO2 fibers after calcination

treatment as a function of the viscosity of the electrospinning solution The

diameter varies from 200 to 2000 nm As expected from the results of as-spun

hollow nanofibers the final product of hollow nanofibers is produced in the

case of lower viscosities In contrast hollow microfibers are produced at

higher viscosities As far as we know no study reported to date has focused on

control over the diameter of hollow oxide fibers The successful control of the

diameter of hollow TiO2 fibers is expected to be useful for practical

applications in the fields of chemical sensors and catalysis

To test the potential use of hollow TiO2 fibers in chemical gas sensors

their CO sensing properties were investigated particularly at room temperature

Figure 24 shows the time dependence of resistance of hollow TiO2 fibers

sensor at different CO concentrations ranging from 01 to 07 ppm The

diameter of the hollow fibers used for the sensor was 200 nm When the sensor

is exposed to CO gas the resistance decreases When the CO supply is stopped

the resistance completely recovers to the initial value It is noteworthy that the

CO sensing property was measured at room temperature The hollow TiO2

fibers have inner and outer surfaces meaning that the surface-to-volume ratio

almost doubles compared with normal solid fibers This allows them to have

CO sensing properties even at room temperature

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

fabricated from the hollow TiO2 fibers whose average diameter was 200 nm

42 CuO-SnO2 heterostructured nanofibers

421 Nanofibers synthesized by single-needle electrospinning

The morphologies of the nanofibers were determined by SEM Figure 25

(a) shows the typical SEM image of as-spun CuO-SnO2 nanofiber synthesized

via basic electrospinning The nanofibers should be the mixture of precursors

(CuCl2 and SnCl2) and polymer as well as some solvent The surfaces of

as-spun nanofibers appear smooth due to the amorphous nature of the

composite Each individual nanofibers was uniform in cross section and the

average diameter of these nanofibers was ~150 nm As shown in Figure 25 (b)

after the polymer was selectively removed by calcined these samples in air at

700 oC the CuO-SnO2 nanofibers remained dense and continuous structures

and their average diameter was reduced to ~100 nm This is due to the loss of

PVAc and crystallization of CuO and SnO2 In spite of the CuO concentration

of these fibers as-spun and calcined nanofibers look almost the same in a

low-magnification SEM image In high-magnification SEM images as shown

in Figure 26 these nanofibers show granular surfaces indicating they consist

of nanosized grains As the increase of CuO concentration the surfaces of

nanofibers became smoother and smoother which means the size of nanosized

grains became smaller as the increase of CuO concentration In pure SnO2

nanofibers the nanogrians are clearly observed while they are hard to be

distinguished in the 05CuO-05SnO2 system This phenomenon might

because the crystallization of CuO is harder than that of SnO2 which is further

confirmed by the XRD pattern

XRD was used to confirm the crystal phase of the CuO-SnO2 nanofibers

Figure 27 shows the XRD pattern of calcined samples with different CuO

concentrations The diffraction peaks obtained from pure SnO2 nanofibers

were well matched the pure cassiterrite phase of SnO2 and no peaks other than

SnO2 were detected suggesting high crystallinity of the nanofibers

Interestingly when Cu element was added into the pure SnO2 system the

peaks trended broader and broader but no peak of CuO phase was detected

which indicated the poor crystallinity of CuO In other hand these nanofibers

might be a solid solution of CuO and SnO2 which means the Cu and Sn atoms

took part in the lattices of CuO and SnO2 molecules As a result in case of

05CuO-05SnO2 system even the peaks of SnO2 phase were disappeared

This poor crystalliniity directly leads to the poor gas sensing properties

described in the following sections

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

ostructured CuO-SnO2 nanofibers (a)

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

To test the potential application of these fibers in chemical gas sensors two

samples (x=001 01) were selected to investigate their H2S sensing properties

H2S is one of the typical toxic inflammable gases and is used as a process gas

or generated as a by-product in laboratories and industrial areas Detection of

H2S is of immense importance in the areas of oil and natural gas exploration

Figure 28 (a) and (b) displays the time dependence of resistance of sensors

based on theses nanofibers at 100 oC The resistance of both sensors decreased

upon exposure to various concentrations of H2S whereas it increased upon the

removal of H2S The sensitivity is defined as RaRg where Ra is the resistance

of sensor in air Rg is the resistance in the tested gas As shown in Figure 29 it

is obviously that sensitivity of the sensor fabricated from 001CuO-099SnO2

is much higher than that of the other one For comparison the bare SnO2

nanofiber sensor was also applied to the detection of H2S at 100 oC The results

are shown in Figure 30 (a) As can be seen the SnO2 nanofiber sensor exhibits

terrible response and recovery compared with the CuO-SnO2 heterostructured

nanofiber sensor both the response and recovery time are extremely long (~1 h

and 4 h)

Selectivity is an important property for gas sensors As we know in theory

typical semiconductor sensor can react with various gases leading to poor

selectivity to specific gas To test the selectivity of heterostructured CuO-SnO2

nanofiber sensors CO gas sensing properties were also investigated As shown

in Figure 28 (c) and (d) the resistances decreased very slightly upon exposure

to 100 ppm of CO and hardly show any response The sensitivity was ~12

which is markedly lower than the sensitivity in H2S gas (see Figure 29) This

result indicates these nanofibers show excellent selectivity to H2S gas

the sensor fabricated from two selected CuO-SnO2 nanofibers (a c) x=001 (b

d) x=01

Gas concentration (ppm)

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

100 ppm 100 oCH2S ON

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

422 Nanofibers synthesized by double-needle electrospinning

Figure 30 (a) shows the typical SEM image of as-spun heterostructured

CuO-SnO2 nanofiber synthesized via double-needle electrospinning Similar

to the as-spun nanofibers obtained by basic electropsinning the as-spun

nanofibers show smooth surface and distributed on the substrate randomly As

shown in the inset the average diameter of as-spun nanofibers was

approximately 200 nm To obtain CuO-SnO2 heterostructured nanofibers the

as-spun nanofibers were calcined at 700 oC in air for 4 h Figure 31 (b) shows

the typical SEM image of calcined nanofibers As we can see after calcination

the nanofibers donrsquot remain continuous structure and some parts become flat

The rupture of nanofibers could be accounted for the low concentration of

copper chloride in the electrospinning solution Usually the average diameter

of nanofibers reduces as the decrease of precursor concentration in the

electrospinning solution If the concentration of precursor is too low due to

the removal of polymer the nanofibers are hard to form thus the nanofibers

were broken down The crystal phase was confirmed by XRD pattern As

shown in Figure 32 all diffraction peaks were indexed to the cassiterrite phase

of SnO2 and no CuO phase was observed As we described before the

concentration of CuO is too low thus the CuO phase was not detected

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

H2S sensing properties of these nanofibers were investigated as functions

of temperature and H2S concentrations As shown in Figure 33 when the

sensor is exposed to H2S gas the resistance decreases whereas the resistance

completely recovers to the initial value upon the removal of H2S The

comparison of sensitivity at different temperatures and concentrations was

shown in Figure 34 The sensitivity increases when the temperature and H2S

concentration increases When the sensor is exposed to 100 ppm of H2S at 300

oC it shows the highest sensitivity of 679 For comparison the bare SnO2

nanofiber sensor was also applied to the detection of H2S at 300 oC As can be

seen in Figure 34 compare to CuO-SnO2 heterostructured nanofibers the

sensitivity is rather low (~20) which indicates the CuO-SnO2 heterostructured

nanofibers show excellent sensing property to H2S gas

0 1000 2000 3000

200 oC

Time (s)

250 oC

100 ppm50 ppmH2S 10 ppm

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

heterostructured CuO-SnO2 nanofibers synthesized via ldquodouble-needlerdquo

electrospinning

H2S concentration (ppm)

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

CuO-SnO2 nanofibers as function of H2S gas concentration at various

temperature

200 250 300

Recovery time Response time

Temperature (oC)

585490

The response and recovery time are defined as the time to reach 90 shift

in resistance upon exposure to H2S and air In the bare SnO2 nanofiber sensor

the response time is even as short as 1 s while the recovery time is ~150 s In

CuO-SnO2 heterostructured nanofiber sensor the response time is still 1 s

while the recovery times were lengthened To our knowledge 1 s of response

time is a indeed small value [6-8] As can be seen in Figure 35 the recovery

times are 585 s 490 s and 305 s at 200 oC 250 oC and 300 oC which is much

longer than that of bare SnO2 nanofiber sensor The difference between these

two kind of materials can be explained with different sensing mechanism

In bare SnO2 nanofibers sensor the following reactions can be accounted

for the sensing process (1) In air charged species such as O2- O- and O2- are

adsorbed on the SnO2 [9] (2) When the sensor is exposure in H2S the

following reaction will happen [10]

H2S (g) + 3O2minus rarr SO2 (g) + H2O + 6eminus

The electrons are released into depletion layer of SnO2 grains resulting in

increase of electric conductivity These two reactions repeat again and again

when the sensor is exposure in air and H2S leading to a switch-like response

Typically the adsorption of charged species is slower than the oxidation

reaction [11-13] so the recovery time is usually longer than response time

In case of CuO-SnO2 it gives a totally different sensing mechanism [14]

Firstly by comparing the initial resistance of bare SnO2 and CuO-SnO2

heterostructured sensors it is obvious that the initial resistance of

heterostructured sensor is ~50 times bigger than that of bare SnO2 sensor This

is attributed to the formation of a thick charge depletion layer as resistive pndashn

junctions at the interfaces between CuO and SnO2 as shown in Figure 36 (a)

However when the sensor is exposed to H2S CuO is converted to CuS which

is a metallic material having good electric conductivity in the following

formula

CuO (s)+H2S (g)rarrCuS (s)+H2O (g)

As a result the charge depletion layer is destroyed and transformed to a

metal-n type semiconductor contact at the interface between CuS and SnO2

Since the work function of CuS is lower than that of SnO2 there is a flow of

electrons from CuS to SnO2 As shown in Figure 36 (b) the formation of a

high density of electron layer caller anti-barrier results in the band bending

downwards which facilitate the easy flow of electrons from CuS to SnO2 and

vice versa Eventually the resistance of the whole senor decreases When the

H2S gas is removed and air is introduced the CuS is converted back to CuO

and thus the charge depletion layer appears again resulting in a high

resistance The reaction formula is as follow

CuS (s)+32O2 (g)rarrCuO (s)+SO2 (g)

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

[1] P K Baumgarten J Colloid Interf Sci 36 (1971) 71

[2] M G McKee G L Wilkes R H Colby T E Long Macromolecules 37

(2004) 1760

[3] P Gupta C Elkins T E Long and G L Wilkes Polymer 46 (2005) 4799

[4] X M Cui W S Lyoo W K Son D H Park J H Choy T S Lee W H

Park Supercond Sci Technol 19 (2006) 1264

[5] D Lin W Pan H Wu J Am Ceram Soc 90 (2007) 71

[6] A Chowdhuri P Sharma V Gupta K Sreenivas K V Rao J Appl

Phys 92 (2002) 2172

[7] X Xue L Xing Y Chen S Shi Y Wang T Wang J Phys Chem 112

(2008) 12157

[8] L He Y Jia F Meng M Li J Liu J Mater Sci 44 (2009) 4326

[9] N Yamazoe J Fuchigami M Kishikawa T Seiyama Surf Sci 86 (1979)

[10] V V Malyshev A V Pislyakov Sens Actuat B 47 (1998) 181

[11] W Y Chung G Sakai K Shimanoe N Miura DD Lee N Yamazoe

Sens Actuat B 46 (1998) 139

[12] G Neri A Bonavita G Micali G Rizzo E Callone G Carturan Sens

Actuat B 132 (2008) 224

[13] C S Moon H R Kim G Auchterlonie J Drennan J H Lee Sens

Actuat B 131 (2008) 556

[14] S Manorama G S Devi V J Rao Appl Phys Lett 64 (1994) 3163

5 Conclusion

In this work the following results were obtained

First hollow TiO2 fibers were synthesized via an electrospinning

technique with a core-shell type needle As-spun fibers were comprised of core

heavy mineral oil-shell titanium isopropoxide plus PVP After calcination

as-spun hollow fibers were transformed into hollow fibers of anatase TiO2

phase Importantly the diameter of the hollow fibers changed from nano- to

micro-scale depending on the viscosity of the electrospinning solutions which

was controlled by changing the content of PVP in the solutions As the

viscosity of the solution was lowered the diameter of the synthesized hollow

fibers was accordingly decreased The sensing properties of the hollow TiO2

fibers with regard to CO were investigated The clear sensing signals to CO at

room temperature were observed in the hollow TiO2 fibers most probably due

to the effect of the increase in surface-to-volume ratio by the generation of

inner surfaces

Second CuO-SnO2 heterostructured nanofibers were synthesized via

electrospinning technique with two syringes and two needles The synthesized

nanofibers were uniform in microstructure Due to the formation and

disruption of hetero-interface between the p-type CuO and n-type SnO2 the

CuO-SnO2 heterostructured nanofibers showed excellent sensitivity and

selectivity to H2S gas It is noteworthy that the response is remarkably fast (1

s) while the recovery is rather slow In future more study should be

undertaken to improve the recovery of sensors

These results indicate that the hollow nanofibers and heterostructured

nanofibers hold promise application in chemical sensing

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion

ltstartpagegt151 Introduction 12 Background 4 21 Synthesis of oxide nanofibers by electrospinning 4 211 Solid nanofibers 4 212 Core-shell nanofibers 10 213 Hollow nanofibers 14 214 Aligned nanofibers 18 22 Gas sensing based on electrospun metal oxide nanofibers 23 221 Background knowledge of gas sensors 23 222 Literature survey 233 Experiment 36 31 Synthesis of hollow TiO2 nanofibers 36 32 Synthesis of CuO-SnO2 heterostructured nanofibers 38 33 Characterization 414 Results and Discussion 42 41 Hollow TiO2 nanofibers 42 42 CuO-SnO2 heterostructured nanofibers 52 421 Nanofibers synthesized by single-needle electrospinning 52 422 Nanofibers synthesized by double-needle electrospinning 605 Conclusion 70ltbodygt

2011 年 2 月

指導敎授金相燮

이 論文을 碩士學位論文으로 提出함

金屬工學科

張進

2011 年 2 月

主審 김현우

副審 김상섭

委員 김형순

Abstract

Content Abstract i

Content iii

List of figures iv

1 Introduction 1

2 Background 4

3 Experiment 36

5 Conclusion 70

List of figures

electrospinning

template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


2011 年 2 月

主審 김현우

副審 김상섭

委員 김형순

Abstract

Content Abstract i

Content iii

List of figures iv

1 Introduction 1

2 Background 4

3 Experiment 36

5 Conclusion 70

List of figures

electrospinning

template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Abstract

Content Abstract i

Content iii

List of figures iv

1 Introduction 1

2 Background 4

3 Experiment 36

5 Conclusion 70

List of figures

electrospinning

template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Content Abstract i

Content iii

List of figures iv

1 Introduction 1

2 Background 4

3 Experiment 36

5 Conclusion 70

List of figures

electrospinning

template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Content Abstract i

Content iii

List of figures iv

1 Introduction 1

2 Background 4

3 Experiment 36

5 Conclusion 70

List of figures

electrospinning

template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


List of figures

electrospinning

template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


template fibers

of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


of spinning time

330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


330 oC

gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


gas concentration

technique

was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


was 200 nm

x=001 (c) x=005 (d) x=01 (e) x=02 (f) x=03 (g) x=04 (h)

x=001 (b d) x=01

300 oC

calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


calcined at 700 oC

various temperature

1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


1 Introduction

Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Reference

(2010) 3604

2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


2 Background

power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


power s

connect

pump i

appropr

electros

and thus

fibers w

techniqu

metal o

and the

after el

high-qu

Figure

electros

supply a sp

ted to a syr

is used to

riate high v

static force

s force the e

will form fro

ue a numbe

xide nanofi

e as-spun na

lectrospinnin

uality metal

1 Schem

spinning

inneret (a m

ringe in wh

feed the p

voltage is a

can overco

ejection of a

om the need

er of polym

ibers some

anofibers n

ng The ca

oxide nano

matic illustr

metallic need

hich the pol

olymer sol

applied betw

me the surf

a liquid jet fr

dle to the co

mer nanofibe

precursors

eed to be c

alcination p

ofibers with

ration of t

dle) and a c

lymer solut

lution at a

tween the n

face tension

from the noz

ollector Wi

ers have bee

are added

calcined at

process is v

good micro

the conven

collector Th

tion is host

constant r

needle and

n of the pol

zzle Eventu

ith this use

en prepared

to the poly

appropriate

very impor

ostructures a

ntional bas

he spinnere

ted A syrin

ate When

collector t

lymer soluti

ually ultra-th

of this simp

For obtaini

mer solutio

e temperatu

tant to obt

and phases

ic set-up

exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


exceeded 05 mlh [2]

D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


D=kC+d0

Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

an ethan

electric

had bee

distribu

of the s

the anat

2 (a) SEM

nol solution

field streng

en calcined

ution of nano

ame calcine

tase phase o

M image of T

n containing

gth was 1 kV

in air at 50

ofibers cont

ed sample A

of titania

TiO2PVP na

Ti(OiPr)4 (

Vcm (b) SE

00 oC for 3

tained in th

All diffracti

anofibers th

(01 gmL) a

EM image o

3 h (c) His

he calcined

ion peaks c

hat were ele

and PVP (0

of the same

stogram sho

sample (d)

can be index

ectrospun fro

03 gmL) T

sample afte

owing the s

) XRD patte

xed to those

Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

acetate

calcinedoC for 1

3 Scannin

polyvinyl a

d at 500 oC f

10 h (e) Dia

ng electron

alcohol com

for 6 h (c) c

ameter of Zn

n microscop

mposite fibe

calcined at 5

nO fibers as

py images

ers with 50

500 oC for 8

s a function

of ZnO fib

wt of zin

h and (d) c

n of calcinat

bers (a) z

nc acetate

calcined at 5

tion time

Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

core-she

solution

co-elect

unstaine

4 (a) Exp

ell nanofibe

ns are PSU

trospun PEO

ed samples

periment se

ers (b) TE

and PEO

O (core) and

of co-electr

etup used fo

EM of a com

respectively

d PDT (shel

rospun PLA

for co-electr

mpound na

y (c) TEM

ll) (d) TEM

A and Pd(OA

rospinning

anofibers C

M of unstain

M of annealed

of compou

Core and sh

ed samples

d (170 oC 2

Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

prepare

and (f) 4

layers

ALD cy

5 Typica

d with diffe

400 Note t

(g) ZnO sh

ycles The s

al FE-SEM

erent ALD c

that (a) repr

hell thicknes

lope indicat

images of

cycles of (a

resents SnO

ss in the co

tes the grow

f SnO2ndashZn

a) 0 (b) 50

O2 core nano

orendashshell na

wth rate of Z

nO corendashshe

(c) 100 (d)

ofibers with

anofibers as

ZnO shell la

ell nanofib

) 200 (e) 3

hout ZnO sh

s a function

method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


method

Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

microgr

SEM sh

prepare

thermal

6 (a) Con

raph with e

howing the

d by coatin

lly induced

nception fo

edge-on view

inner surfa

ng electros

degradation

r preparatio

w of a lay

ace of PPX

pun PLA f

n of the tem

on of hollo

yered arrang

tubes (d)

fibers with

mplate fibers

ow nanofib

gement of P

SEM of alu

aluminum

ers (b) SE

PPX tubes

uminum tub

followed

Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

having

after the

(anatase

nanotub

anatase

electrod

mineral

03 and

7 (a) Schem

a coreshea

e oily cores

e) hollow

bes in air at

hollow fib

des In the p

l oil was 01

003 gmL

matic illustr

ath structure

s had been

fibers that

t 500 oC (d

bers that we

preparation

1 mLh and

respectivel

ration of the

e (b) TEM

extracted w

t were obt

d) SEM im

ere collecte

of all these

d the concen

ly The volt

e setup for e

image of tw

with octane

tained by

mage of a un

ed across th

e samples t

ntrations of

tage of elect

electrospinn

wo as-spun

(c) TEM i

calcining t

niaxially ali

he gap betw

the feeding

Ti(OiPr)4 a

trospinning

ing nanofib

n hollow fib

image of Ti

the compos

igned array

ween a pair

rate for hea

and PVP w

was 12 kV

collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


collector

Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

used to

pieces o

field str

arrows

force an

8 (a) Sche

generate u

of conductiv

rength vecto

denote the

nalysis of a

ematic illus

uniaxially al

ve silicon st

ors in the re

direction o

charged nan

tration of th

ligned nano

tripes separa

egion betwe

of the elect

nofiber span

he setup fo

ofibers The

ated by a ga

een the need

trostatic fie

nning acros

r electrospi

e collector

ap (b) Calc

dle and the

ld lines (c

ss the gap

inning that

contained t

culated elect

collector T

) Electrosta

Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

are colle

in the m

electros

conduct

time (f

9 (a) Plexi

ected on the

magnified im

spinning S

tive copper

g) after 15

iglas disk w

e copper wi

mage (b) Ap

SEM image

wire drum

min (h i a

with copper

ires The nan

pparatus for

es of axial

(c d and

and j) after 4

wires Elec

nofiber mat

rotating the

lly aligned

e) alignmen

40 min and

ctrospun nyl

t shows stra

e copper wir

polymer n

nt after 5 m

(k) after 25

lon nanofib

atified layeri

re drum duri

nanofibers

min of spinni

5 h of spinni

CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


CO+O-rarrCO+e-

NO2+e- rarrNO2-

concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


concentration [11]

Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

fabricat

after ho

nanofib

cyclic e

in dry a

histogra

10 (a) SE

ted by electr

ot pressing

bers after ca

exposure to

air at various

am upon exp

EM image

rospinning

at 120 oC f

alcination a

alcinations

10 min puls

s operating

posure to 50

of the as-

(b) SEM im

for 10 min

at 450 oC (

at 450 oC

ses with incr

temperature

00 ppb NO2

-spun TiO2

mage of TiO

(c) SEM i

(d) SEM im

(e) The re

reasing con

es (b) Sens

2 in dry air

2PVAc com

O2PVAc co

image of un

mage of hot

esistance re

ncentrations

itivity versu

mposite fib

npressed Ti

t pressed Ti

sponse duri

of NO2 mix

us temperatu

Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

calcinat

nanofib

the prod

to 1000

11 (a) SEM

tion of the p

bers The ins

ducts(e) Re

ppm (f) Cr

M image of

precursors a

set in (c) is S

esponse tran

ross sensitiv

f the precurs

at 600 oC fo

SAED patte

nsients of th

vity of the s

sors (b) Zn

for 5 h (c) T

ern of the pr

he sensor to

sensor to va

O nanofiber

TEM image

oduct (d) X

ethanol cha

arious gases

rs prepared

e of pure Zn

XRD pattern

anging from

Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

magnifi

operatin

in the r

function

12 (ab

ications (d)

ng temperat

range of 00

n of ethanol

c) SEM i

) Response o

ture (e) Res

01ndash5000 pp

l concentrat

images of

of the senso

sponsereco

pm at 330 o

tion at 330 o

f SnO2 na

or to 200 ppm

anofibers w

m ethanol a

s of the sen

ponse of th

with differ

as a function

nsor to ethan

he sensor a

layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


layer [5]

Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

sensor t

(b) The

respons

the data

nanofib

corendashsh

obtained

concent

13 (a) Dy

to O2 The in

variation o

se of the Zn

a obtained a

ber sensor as

hell nanofibe

d at 1 ppm

tration conc

ynamic resp

nset is the e

f sensitivity

nO nanofibe

at 300 ppm

s a function

er sensor to

NO2 (f) T

centration

ponse of th

enlarged par

y as a functi

er sensor to

O2 (d) The

n of O2 (e) D

o NO2 The

he variation

he SnO2ndashZ

rt of the data

ion of O2 co

O2 The ins

e variation

Dynamic re

inset is the

n of sensitiv

ZnO corendashsh

a obtained a

oncentration

set is the en

of sensitivi

esponse of t

e enlarged p

vity as a fu

hell nanofib

at 300 ppm O

n (c) Dynam

nlarged part

ity of the Z

the SnO2ndashZ

part of the d

nction of N

Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

insets a

m-ZndashS

versus

chemica

14 SEM i

are TEM i

nanofibers

ethanol co

al sensing o

images of (

mages and

(c) Four

exposed to

oncentration

of mesoporo

(a) m-ZndashS n

d nitrogen a

cycles of r

different et

n in the ra

ous ZndashS nan

nanofibers

adsorptionndash

responsendashre

thanol conc

ange 5ndash100

nofibers

(b) ZndashS na

ndashdesorption

ecovery cha

centrations

000 ppm (

anofibers T

isotherms

aracteristics

(d) Sensitiv

(e) Sketch

Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

SnO2-Z

element

nanofib

compari

nanofib

gas con

15 SEM

ZnO hybrid

tal mapping

ber of 72 nm

bers-based

ison of NO

bers (blue) a

ncentration

images of

nanofibers

g of Zn (r

m in diamet

sensor as

O2 response

and the SnO

(a) the pri

The image

red) and S

ter (e) NO2

a function

es for gas

O2-ZnO hyb

istine ZnO

es of (c) br

Sn (green)

2 responses

n of worki

sensor bas

brid nanofib

nanofibers

right-field S

for a SnO

of the SnO

ng tempera

sed on the

bers (red) as

s and (b)

STEM and

O2-ZnO hyb

ature (f) T

pristine Zn

s a function

Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Reference

[2] D Li Y Xia Nano let 3 (2003) 555

15 (2003) 1929

Nano let 6 (2006) 2009

Am Ceram Soc 91 (2008) 3817

075501

Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Actuat B 145 (2010) 592

3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


3 Experiment

syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


syringe

materia

the elec

kV and

substrat

tip of th

tempera

for 12

subsequ

isoprop

fibers a

synthes

Figure

core-she

e prepared s

connected

l was loade

ctrospinning

the feeding

tes placed on

he needle A

ature and air

h to remo

uently drie

oxidePVP

at 600 oC

16 Schem

ell needle u

solution of t

to the outer

ed to anothe

g process th

g rate was a

n the alumin

All the electr

r ambient T

ove mineral

ed at room

fibers wer

for 2 h cr

matic illust

used in this s

itanium isop

r needle Wh

er syringe c

he applied v

adjusted bet

num collect

rospinning e

The as-spun

l oil existin

m tempera

re finally o

rystalline h

ration of th

propoxide a

hile heavy m

connected to

voltage was

tween 005

tor were loc

experiments

n fibers were

ng in the

ature for

obtained By

hollow TiO

he electrosp

and PVP wa

mineral oil

o the inner n

varied betw

and 03 ml

ated 20 cm

s were carri

e then imme

cores of th

6 h Hol

y calcining

2 fibers we

pinning tech

as loaded int

used as a co

needle Duri

ween 20 and

h The silic

away from t

ed out at roo

ersed in octa

he fibers a

llow titaniu

these holl

ere eventua

hnique with

needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


needles

SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


SnO2 so

electros

rate wa

collecto

electros

ambient

heterost

Figure

techniqu

case of dou

olution wer

spinning pro

s fixed at

or were loc

spinning ex

t By calcin

tructured Cu

17 Schem

uble-needle

re loaded in

ocess the ap

003 mlh

cated 20 cm

xperiments w

ning the as-

uO-SnO2 fib

matic illustr

elextrospinn

nto two gla

pplied voltag

The silicon

m away fr

were carrie

-spun nano

bers were e

ration of th

ning the pr

ass syringe

ge was fixed

n substrates

rom the tip

ed out at ro

ofibers at 70

eventually sy

he ldquodouble

repared CuO

individuall

d at 20 kV a

placed on

p of the ne

oom tempe

00 oC for 4

ynthesized

e-needlerdquo e

O solution a

ly During

and the feedi

the aluminu

eedle All

rature and

4 h crystall

lectrospinni

33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


33 Characterization

Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

concent

18 SEM

trations (a) 0

images o

004 (b) 00

f as-spun

06 (c) 008

hollow fib

and (d) 0

bers with d

different PVVP

004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


004 006 008 010

200 400 600 8000

D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


D - D0 = kη (1)

10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


10 100 1000102

TiO2 this work

ZnO ref 18 YBa

7- ref 17

continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


continu

Shrinka

decomp

displays

from the

with tho

Figure oC for 2

correspo

ous uniform

age in the

position of T

was used to

s an XRD p

e solution c

ose of the pu

21 SEM im

2 h with diff

ml The i

onding over

m thread in

diameter

Ti precursor

confirm th

pattern obta

ontaining 0

ure anatase

mage of TiO

ferent PVP c

nsets are

rall morpho

n each fiber

of the fib

rs during th

he phase of

ained from

4 gml of PV

phase of Ti

O2 hollow fib

concentratio

low-magni

ologies of th

r during the

bers due to

he calcinatio

f the hollow

hollow TiO

VP All the

bers obtaine

on (a) 004

ified SEM

he fibers

e electrospin

o removal

on process i

w TiO2 fibe

O2 nanofibe

peaks corre

ed after calc

(b) 006 (c

M images

nning proce

of PVP a

s also evide

ers Figure

rs synthesiz

espond clos

cination at 6

c) 008 and

revealing

20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


20 30 40 50 60 70 80

0)(116

2 (degree)

200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


200 400 600 800

0 300 600 900 1200 1500

07 ppm05 ppm02 ppm

Air ON

Time (s)

CO ON 25 oC

01 ppm

Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

as-spun

25 Typical

n (b) calcine

l SEM imag

ed at 700 oC

ge of hetero

Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

26 SEM im

(c) x=005

mage of het

(d) x=01 (e

terostructur

e) x=02 (f)

red CuO-Sn

x=03 (g) x

nO2 nanofib

x=04 (h) x=

ers (a) x=0

20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


20 30 40 50 60 70 80

2degree)

and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


and 4 h)

d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


d) x=01

10 50 100

0 1000 2000 3000 4000

27k10 ppm 100 oC

Air ON

Time (s)

(c)0 4000 8000 12000 16000

10 ppm 100 oC

Air ON

)Time (s)

0 2000 4000 6000 8000

100 oC

100 ppm50 ppm

10 ppm

Air ON

H2S ON

Time (s)

(a)0 1000 2000 3000 4000 5000 6000

100 ppm50 ppm

10 ppm

100 oC

Time (s)

H2S ON

Air ON (b)

300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


300 oC

0 3000 6000 9000 12000 15000

Time (s)

Air ON(a)

0 300 600 900 1200100

300 oC

100 ppm50 ppm10 ppm

Air ON

H2S ON

Time (s)

Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Figure

synthes

700 oC

31 SEM

ized via ldquod

image of t

double need

typical hete

dlerdquo electros

erostructure

spinning (a

ed CuO-Sn

a) as-spun (

O2 nanofib

(b) calcined

20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


20 30 40 50 60 70 80

2 (degree)

nit) (1

0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


0 1000 2000 3000

200 oC

Time (s)

250 oC

Air Air Air

100 ppm50 ppm

H2S 10 ppm

Air Air

Air Air Air

300 oC

electrospinning

pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


pure SnO2 300 oC

200 oC

250 oC

300 oC

10 50 100

temperature

200 250 300

Temperature (oC)

585490

formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


formula

Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Notice t

that as

Figure 3

Figure

that this re

the increas

36 (a) Ban

eaction take

se of tempe

nd diagram o

es place at h

erature the r

of CuO-SnO

high temper

recovery te

O2 (b) band

rature so w

mperature d

diagram of

we can obser

decreases (s

f CuS-SnO2

Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Reference

(2004) 1760

Phys 92 (2002) 2172

(2008) 12157

Actuat B 132 (2008) 224

Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Actuat B 131 (2008) 556

5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


5 Conclusion

inner surfaces

1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


1 Introduction

2 Background









3 Experiment



33 Characterization






5 Conclusion


Documents

Synthesis of TiO2 and CuO-SnO2 nanofibers by · Synthesis of TiO2 and CuO-SnO2 nanofibers by electrospinning and their gas sensing properties 2011年 2月 仁荷大學校 大學院

Synthesis of TiO2 and CuO-SnO2 nanofibers by · Synthesis of TiO2 and CuO-SnO2 nanofibers by electrospinning and their gas sensing properties 2011年 2月仁荷大學校大學院