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Oxygen Reduction
Reaction
氧还原反应
主讲人：王文心
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Contents
Oxygen Reduciton Reaction
Mechanism of ORR
Catalysts for ORR
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Redox Reaction
Redox (reduction-
oxidation) reactions
include all chemical
reactions in which atoms
have their oxidation state
changed.
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ORR in Fuel Cell
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Mechanism
Electrolyte ORR reactions
Thermodynamic
electrode
potential at
standard
conditions, V
Acidic aqueous
solution
1.229
0.70
1.76
Alkaline
aqueous solution
0.401
-0.065
0.087
Non-aqueous
aprotic solvents
a
b
a, b: The thermodynamic potential for the 1-electron reduction
reaction to form a superoxide, and its further reduction to O22-,
are not listed in this table because their values are strongly
dependent on he solvent used.
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Mechanism
4-electron
Reduction
pathways
2-electron
reduction
pathways
1-electron
Reduction
pathways
Adsorbed O2intermediate
products
Catalysts
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RRDE
Rotating Disk Electrode (RDE)
Rotating Ring-Disk Electrode (RRDE)
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RRDE Research
The
Simplest
Model
H2O2Disproportio
nation/oxidat
ion Model
H2O2Adsorbed
State Model
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The Simplest Modeldiff
bulk
O2 O2surface
+4e-, k1 H2O (or OH-)
H2O2 (or HO2-)
bulk
ring electrode
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The Simplest Model
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H2O2 Disproportionation/oxidation Modeldiff
bulk
O2 O2 (A)surface
+4e-, k1 H2O
H2O2 (B)
lost
ring electrode
k4
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H2O2 Disproportionation/oxidation Model
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H2O2 Adsorbed State Modeldiff
bulk
O2 O2surface
+4e-, k1 H2O (or OH-)
H2O2 ad
k’5 k5
H2O2 solution
bulk
ring electrode
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DFT-calculation
J K Norskov, et al, Journal of Physical Chemistry B, 2004,
108(46): 17886–17892
Results for low oxygen coverage are shown at zero cell potential
(U = 0), at the equilibrium potential (U = 1.23 V), and at the
highest potential (U = 0.78 V) where all reaction steps are
exothermic. For U = 1.23 V, the free-energy diagram for the case of
an oxygen coverage of 1/2 is included.
Free-energy diagram for oxygen reduction at two
different potentials and at two different oxygen coverages,
including the barrier for O2dissociation.
The Simplest Model The Associative Mechanism
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Polarography
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ORR Catalysts
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O2 Adsorption on Electrode
Griffths
Pualing
Bridge
O O
M
O O
M M
O
O
M
Electrode Surface
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Category of ORR Catalysts
氧还原催化剂：
铂系阴极催化剂，非铂系催化剂。
Catalyst 1
Pt-M/C合金催化剂
Catalyst 2
过渡金属含氮大环化合物催
化剂
Catalyst 3
导电聚合物催化剂
Catalyst 4
过渡金属硫属化合物催化剂
Catalyst 5
金属碳、氮、氧化物催化剂
其中，Pt-M催化剂均属于铂系催
化剂；其余四类催化剂归属于非铂系催化剂。
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M-Nx/C Catalysts
W. Li, et al, J. Am. Chem. Soc., 2010, 132, 17056–17058.
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Conducting Polymer
R. Bashyam and P. Zelenay, Nature, 2006, 443, 63–66.
Polymer electrolyte H2-O2 fuel cell
Schematic representation of the Co-polypyrrole
compositeCatalyst： a, Polypyrrole structure. b, Presumed
configuration of the Co-PPY catalyst after the entrapment of the
cobalt precursor, Co(NO3)26H2O into polypyrrole and reduction with
NaBH4.
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Pt-Alloy Catalysts
Jalan V, et al, Journal of the Electrochemical Society,
1983, 130(11): 2299–2302
Specific activity for the ORR vs. electrocatalysts
nearest-neighbor Chao Wang, et al. Phys.
Chem.
Lett., 2012, 3 (12), pp
1668–1673
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Design the catalysts
I. Stephens, et al., Energy
Environ. Sci., 2012, 5, 6744.
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Future
H. A. Gasteiger, & N. M. Markovic Science 2009, 324, 48.
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My Work-unpublished
5nm 50nm
P. Liu, et al. Langmuir, 2009, 25, 561.
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My Work-unpublished
0.0 0.2 0.4 0.6 0.8 1.0 1.2-7
-6
-5
-4
-3
-2
-1
0
1
j ele
ctr
od
e s
urf
ace / m
Acm
2
Potential / V (vs RHE)
commercial Pt/C
NPG-Pd1Pt
NPG-Pd2Pt
NPG-Pd3Pt
NPG-Pd4Pt
∆=41mV
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Thanks for your
attention!
