Electrochemical oxygen reduction, kinetic

Kinetic and Mechanistic Aspects of Electrochemical Oxygen Reduction... 

Gottesfeld S, Raistrick ID, Srinivasan S. Oxygen reduction kinetics on a platinum RDE coated with a recast Nafion film. J Electrochem Soc 1987 134(6) 1455-62. 

Qiao J, Xu L, Ding L, Shi P, Zhang L, Bake R, et al. Effect of KOH concentration on the oxygen reduction kinetics catalyzed by heat-treated Co-Pyridine/C electrocatalysts. Int J Electrochem Sci 2013 8 1189-208. 

Ye HC, Crooks RM (2007) Effect of elemental composition of PtPd bimetallic nanoparticles containing an average of 180 atoms on the kinetics of the electrochemical oxygen reduction reaction. J Am Chem Soc 129(12) 3627-3633... 

Neyerlin KC et al (2005) Effect of relative humidity on oxygen reduction kinetics in a PEMFC. J Electrochem Soc 152(6) A1073-A1080... 

In PEM fuel cells, the exchange current density for the electrochemical oxygen reduction reaction (ORR, 10 -10 A cm ) is much smaller than that of the hydrogen oxidation reaction (HOR, 10 -10 A cm ). Due to the larger HOR exchange current density, the HOR at the anode Pt nanoparticle/PEM interface is much faster than the ORR at the cathode interface [14]. In other words, the overpotential for the HOR is negligibly small compared with that of the ORR when the anode is adequately hydrated. The overall electrochemical kinetics of PEMFCs is therefore dominated by the relatively slow oxygen reduction reaction. 

The functions of porous electrodes in fuel cells are 1) to provide a surface site for gas ionization or de-ionization reactions, 2) to provide a pathway for gases and ions to reach the catalyst surface, 3) to conduct water away from the interface once these are formed, and 4) to allow current flow. A membrane electrode assembly (MEA) forms the core of a fuel cell and the key electrochemical reactions take place in the MEA. MEA performance is severely affected by electrode composition, structure, and geometry, and especially by cathode structure and composition, due to poor oxygen reduction kinetics and transport liniitations of the reactants in the cathode catalyst layer. 

The kinetics and mechanism of electrochemical oxygen reduction at different catalysts has been widely studied from the late 1950s onward, as can be seen in the monographs of Hoare (1968), Breiter (1969), and Kinoshita (1992). 

Neyerlin, K. C., Gasteiger, H. A., Mittelstaedt, C. K., Jorne, J., and Gu, W. (2005) Effect of relative humidity on oxygen reduction kinetics in a PEMFC. Journal of the Electrochemical Society 152(6), A1073-A1080. 

Okada, T, Satou, H. emd Yuasa, (20(B) M. Effects of Additives on Oxygen Reduction Kinetics at the Interface between Platinum and Perfluorinated lonomer. Langmuir 19, 2325-2332 Osawa, M. (1997) Dynamic Processes in Electrochemiceil Reactions Studied by Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS). Bull. Chem. Soc. Jpn. 70, 2681-2880 Shiroishi, H., Ayato, Y, Kunimatsu, K. and Okada, T. (2004) Effect of Additives on Electrochemical Reduction of Oxygen in the Presence of Methanol. Chemistry Lett. 33,792-793 Shiroishi, H., Ayato, Y., Okada, T. and Kunimatsu, K. (2(X)5) Mechanism of Selective Oxygen Reduction on Platinum by 2-2 -Bipyridine in the Presence of Methanol. Langmuir 21, 3037-3043... 

Parimi NS, Umasankar Y, Atanassov PB, Ramasamy RP. Kinetic and mechanistic parameters of laccase catalyzed direct electrochemical oxygen reduction reaction. ACS Catal 2012 2 38. ... 

Neyerlin K C, Gasteiger H A, Mittelsteadt C K, Jome J and Gua W (2005) Effect of Relative Humidity on Oxygen Reduction Kinetics in a PEMFC, J. Electrochem. Soc., 152, pp. A1073-A1080. 

This is a simplified treatment but it serves to illustrate the electrochemical nature of rusting and the essential parts played by moisture and oxygen. The kinetics of the process are influenced by a number of factors, which will be discussed later. Although the presence of oxygen is usually essential, severe corrosion may occur under anaerobic conditions in the presence of sulphate-reducing bacteria Desulphovibrio desulphuricans) which are present in soils and water. The anodic reaction is the same, i.e. the formation of ferrous ions. The cathodic reaction is complex but it results in the reduction of inorganic sulphates to sulphides and the eventual formation of rust and ferrous sulphide (FeS). 

The overpotentials for oxygen reduction and evolution on carbon-based bifunctional air electrodes for rechargeable Zn/air batteries are reduced by utilizing metal oxide electrocatalysts. Besides enhancing the electrochemical kinetics of the oxygen reactions, the electrocatalysts serve to reduce the overpotential to minimize... 

Parthasarathy A, Srinivasan S, Appleby AJ, et al. 1992a. Temperature dependence of the electrode kinetics of oxygen reduction at the platinum/Nafion interface—A microelectrode investigation. J Electrochem Soc 139 2530-2537. 

Lawson DR, Whiteley LD, Martin CR. 1988. Oxygen reduction at Nafion film-coated platinum electrodes Transport and kinetics. J Electrochem Soc 135 2247-2253. 

Gnanamuthu DS, Petrcelli JV. 1967. A generalized expression for the Tafel slopes and the kinetics of oxygen reduction on nohle metal and alloys. J Electrochem Soc 114 1036-1041. 

Markovic N, GasteigerH, Ross PN. 1997a. Kinetics of oxygen reduction on ViQikl) electrodes Implications for the crystalhte size effect with supported Pt electrocatalysts. J Electrochem Soc 144 1591-1597. 

Lawson, D. R., Whiteley, L. D., Martin, C. R., Szentimay, M. N. and Song, J. I. 1988. Oxygen reduction at Nation film-coated platinum electrodes Transport and kinetics. Journal of the Electrochemical Society 135 2247-2253. 

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