生物电分析化学Electroanalytical Chemsitry and

Its Biological Applications

刘宏2015 年秋

课程目标

掌握核心概念和原理 具备在该领域的继续学习的能力

Syllabus

双语教学 不点名，作业不计分 开卷考试 教师邮箱 : liuh@seu.edu.cn

答疑与讨论：河海院 121 室 课程网页 : http://www.liuhong.info/?page_id=211

1.Overview of electrochemistry（电化学概论）

2.Equilibrium (平衡 )

3.Electrochemical Kinetics (电化学动力学 )

4.Mass-transfer（传质）

5.Potential step/sweep techniques (电势阶跃 /扫描技术 )

6.Ultra-microelectrode (超微电极， UME)

7.Scanning electrochemical Microscope (扫描电化学显微镜， SECM)

8.Finite-element simulation of electrochemical processes (电化学过程的有限元模拟 )

9.Applications ： biomedical diagnostics ， sensors, biofuel cell ， brain research

and single-cell studies（实际应用 : 生物医学诊断、传感器、生物燃料电池、脑科学、单细胞

研究）

课程大纲

Textbook

巴德（ Bard A.J. ），福克纳（ Faulkner L.R. ）著，邵元华 等译化学工业出版社 2005-5-1

Allen Bard 教授2013 美国国家科学奖章

Electrochemistry

Electrochemistry is the study of chemical reactions which take place at

the interface of an electrode, usually a solid metal or a semiconductor,

and an ionic conductor, the electrolyte.

These reactions involve electric charges moving between the electrodes

and the electrolyte (or ionic species in a solution). Thus electrochemistry

deals with the interaction between electrical energy and chemical

change.

Overview of electrochemistry

1. Electrochemical cell (electrolytic, galvanic)

2. Half cell and standard reduction potential

3. Nernst equation

4. Three-electrode cell

5. Potential step techniques (chronoamperometry,

chronocoulometry)

6. Potential sweep techniques (LSV, CV)

Electrochemical parameters

1. Charge (q)

2. Potential (E)

3. Current (i)

4. Capacitance (C)

5. Resistance (R)

6. Conductance (G)

Electrochemical cell

Spontaneous

Generate power

Cell voltage > 0

Non-spontaneous

Consume power

Cell voltage < 0

Electrochemical cell

Battery discharge: galvanic cell

Battery charge: electrolytic cell

Half Cell

E = 0.340 V

E = -0.763 V

1.

2.

Cell voltage: 0.340 V - (-0.763 V) = 1.103 V

thermodynamic, at standard conditions

Nernst Equation

]Fe(CN)[

]Fe(CN)[log059.0

46

36'0

EEE0’ – standard reduction potential

R – gas constant R=8.314 (J/mol/K)

T- absolute temperature T=273.15+t (K)

n – electron transferred

F – Faraday constant F= 96485 (C/mol)

Co(x=0) – concentration of oxidized species

CR(x=0) – concentration of reduced species

X=0 means “on the electrode surface”

Electrochemical CellsTwo-electrode cell: Three-electrode cell:

iR drop: EiRs= iRs

If Rs=100 Ω, i=1mA, EiRs= 0.1V

Reference Electrode

E0’= 0.222 V vs. NHE

]Cl[

1log059.0'0

EE

Faraday’s Law

Faraday’s law:

Nonfaradaic processes charging/discharging

Faradaic processes redox (reducing/oxidizing) events

n is number of moles (n = m/M)t is the total time the constant current was applied.z is the no. of electrons transferred.

zF

itn

Non-Faradaic Processes

Faradaic Processes

Electrochemical Kinetics

Mass Transfer

Nernst-Plank Equation:

Diffusion:

Migration:

Convection:

If the solution is kept still and excess supporting electrolyte (KCl or KNO3) is added to the solution, the contribution of convection and migration can be negligible .

Potential Step Techniques Chronoamperometry ：

Cottrell equation for a planar electrode:

O + ne- R

DO ： diffusion coefficient of OCO ： concentration of O

O R

CO(x=0)

CO*

Potential Sweep Techniques

Non-Faradaic ProcessesPotential Sweep ：

Faradaic Processes

Assignment1. Select two half cells listed in the table on Page 13 to construct (a) an

electrolytic cell and (b) a galvanic cell. Write down the anodic, cathodic and overall reactions. Calculate the cell voltages at (a) standard conditions and (b) if the concentration of every solute is 1.00 mM.

2. Explain why we want to use a three electrode system in a potential-step experiment.

3. A 0.1 cm2 electrode with Cd=20 F/cm2 is subjected to a potential step under conditions where Rs is 1, 10, 100 Ω. In each case, what is the time constant, and what is the time required for the double-layer charging to be 95% complete?

4. Consider the nernstian half-reaction:

the i-E curve for a solution at 25 0C containing 2.00 mM A3+ and 1.00 mM A+ in excess electrolyte shows il,c = 4.00 and il,a = -2.40 Sketch the i-E curve for this system.

NHE vs.V 0.500- E A 2e A /AA 0'3

3

Assignment