Electrocatalytic reduction of oxygen

Alt H, Binder H, Sandstete G (1973) Mechanism of the electrocatalytic reduction of oxygen on metal chelates. J Catal 28 8-19... 

Toda T, Igarashi H, Watanabe M. 1998. Role of electronic property of Pt and Pt alloys on electrocatalytic reduction of oxygen. J Electrochem Soc 145 4185-4188. 

El-Deab MS, Ohsaka T. 2002b. An extraordinary electrocatalytic reduction of oxygen on gold nanoparticles-electrodeposited gold electrodes. Electrochem Commun 4 288-292. 

Gadamsetti K, Swavey S. 2006. Electrocatalytic reduction of oxygen at electrodes coated with a bimetallic cobalt(II)/platinum(II) porphyrin. J Chem Soc Dalton Trans 5530. 

DR. DAVID STANBURY (Rice University) With regard to the problem of the electrocatalytic reduction of oxygen, I have attempted to formalize some ideas regarding the constraints of thermodynamics in order to elucidate the probable character of cobalt complexes which may catalyze the oxygen electrode via binuclear peroxo-bridged intermediates. The following gross mechanism is presupposed ... 

For the study of the electrocatalytic reduction of oxygen and oxidation of methanol, our approach to the preparation of catalysts by two-phase protocol " provides a better controllability over size, composition or surface properties in comparison with traditional approaches such as coprecipitation, deposition-precipitation, and impregnation. " The electrocatalytic activities were studied in both acidic and alkaline electrolytes. This chapter summarizes some of these recent results, which have provided us with further information for assessing gold-based alloy catalysts for fuel cell reactions. 

The electrocatalytic activity of the nanostructured catalysts was investigated for electrocatalytic reduction of oxygen and oxidation of methanol. Several selected examples are discussed in this section. The results from electrochemical characterization of the oxygen reduction reaction (ORR) are first described. This description is followed by discussion of the results from electrochemical characterization of the methanol oxidation reaction (MOR). 

M. M. Maye, N. N. Kariuki, J. Luo, L. Han, P. Njoki, L. Wang, Y. Lin, H. R. Naslund, and C. J. Zhong, Electrocatalytic reduction of oxygen Gold and Gold-platinum nanoparticle catalysts prepared by two-phase protocol. Gold Bull. 37, 217-223 (2004). 

Electrocatalytic Reduction of Dioxygen The electrocatalytic reduction of oxygen is another multi-electron transfer reaction (four electrons are involved) with several steps and intermediate species [16]. A four-electron mechanism, leading to water, is in competition with a two-electron mechanism, giving hydrogen peroxide. The four-electron mechanism on a Pt electrode can be written as follows ... 

Summarizing the state of the art for the electrocatalytic reduction of oxygen the following statements can be made. 

One such reaction that has been studied is the electrocatalytic reduction of oxygen directly to water.25,27 The electrocatalysts for this process are often based on metal porphyrins and phthalo-cyanins. Thus a graphite electrode whose surface was modified by the irreversible adsorption of a cofacial dicobalt porphyrin dimer was able to reduce oxygen under conditions where the reduction did not occur on the bare electrode itself. Similarly, a catalytic chemically modified electrode for the oxidation of chloride to chlorine has been prepared28 where the active catalyst was reported to be a ruthenium dimer, [(bipy)2(OH)RulvORuvO(bipy)2]4+, which was reduced to the corresponding [Rum-RuIV] dimer during the reaction. 

For polymer electrolyte membrane fuel cell (PEMFC) applications, platinum and platinum-based alloy materials have been the most extensively investigated as catalysts for the electrocatalytic reduction of oxygen. A number of factors can influence the performance of Pt-based cathodic electrocatalysts in fuel cell applications, including (i) the method of Pt/C electrocatalyst preparation, (ii) R particle size, (iii) activation process, (iv) wetting of electrode structure, (v) PTFE content in the electrode, and the (vi) surface properties of the carbon support, among others. ... 

The electrocatalytic reduction of oxygen according to the overall equations following a direct four-electron pathway (Eqs. 9-6 and 9-7) ... 

In this case the electrocatal5dic oxidation of ethanol is coupled with the electrocatalytic reduction of oxygen. This reaction can be carried out with modem oxidation cells containing ion exchange membranes instead of liquid electrolytes, represented by the following arrangement including Equations 9-25 and 9-26. 

Kobayashi, N. and W.A. Nevin (1996). Electrocatalytic reduction of oxygen using water-soluble iron and cobalt phthalocyanines and porphyrins. Appl. Organomet. Chem. 10, 579-590. 

Metallophthalocyanines, MPc, are known for their high thermal stability and very low solubility in any solvents. Transition metal-based phthalocyanines have attracted attention in the areas of fuel cells, gas sensors and biosensors . Most of these applications require the use of phthalocyanines in the form of thin films. Further, it is desirable to have ordered, well-packed, and oriented molecular layers of phthalocyanines on various substrates. The metal phthalocyanines constitute an important class of compounds that provide models for theoretical and experimental studies involving electron-mediated processes one of the main areas of interest is the electrocatalytic reduction of oxygen by metal phthalocyanines. ... 

Rywkin, S., C.M. Hosten, J.R. Lombardi, and R.L. Birke (2002). Surface-enhanced resonance Raman scattering and voltammetry stndy of the electrocatalytic reduction of oxygen by the /i-oxo dimer of iron(III) tetra-4-Al-methylpyridylporphyrin. Langmuir 18, 5869. 

Tse Y, Janan P, Lam H, Zhang J, Pietro W, Lever A. Monomeric and polymeric tetra-aminophthalocyanatocobalt(ll) modified electrodes electrocatalytic reduction of oxygen. J Porphyrins Phthalocyanines 1997 01(01) 3—16. 

Electrocatalytic reduction of oxygen molecules was observed with graphite electrode coated with PXV-PSS complex. With respect to oxygen reduction, the catalytic activity of metal porphyrin complexes or metal phthalocyanine complexes adsorbed on the graphite surfaces has been reported by many workers and the mechanism was elucidated by using the rotatii disk or rotatii rii -disk voltammetry25.26 there are a few reports concernii the activity of electrode coated with... 

Okunola A, Kowalewska B, Bron M, Kulesza PJ, Schuhmann W (2009) Electrocatalytic reduction of oxygen at electropolymerized films of metalloporphyrins deposited onto multi-walled carbon nanotubes. Electrochim Acta 54(7) 1954—1960... 

Masa J, Schilling T, Bron M, Schuhmann W (2011) Electrochemical synthesis of metal-polypyrrole composites and their activation for electrocatalytic reduction of oxygen by thermal treatment. Electrochim Acta 60 410-418... 

Yang J, Liu D-J, Kariuki NN, Chen LX (2008) Aligned carbon nanotubes with built-in FeN4 active sites for electrocatalytic reduction of oxygen. Chem Commun 3 329-331... 

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