Electrochemical reduction, of oxygen

The electrochemical reduction of oxygen usually proceeds via two well-separated two-electron steps. The first step corresponds to the formation of hydrogen peroxide ... 

However, no such catalysis was detected. The reason was that even very small amounts of iodide adsorbed on the platinum electrode strongly inhibited the electrochemical reduction of oxygen. A less dramatic but more instructive example was provided by Xiao and Spiro s study of the reaction... 

Bregoli LJ. 1978. The influence of platinum crystallite size on the electrochemical reduction of oxygen in phosphoric acid. Electrochim Acta 23 489-492. 

Genies L, Eaure R, Durand R. 1998. Electrochemical reduction of oxygen on platinum nanoparticles in alkaline media. Electrochim Acta 44 1317-1327. 

El-Deab MS, Okajima T, Ohsaka T. 2003. Electrochemical reduction of oxygen on gold nano-particle-electrodeposited glassy carbon electrodes. J Electrochem Soc 150 A851-A857. 

Vassilev P, Koper MTM. 2007. Electrochemical reduction of oxygen on gold surfaces A density functional theory study of intermediates reaction paths. J Phys Chem C 111 2607-2613. 

The electrochemical reduction of oxygen to form hydrogen peroxide is a very interesting process which has not suffered the expected development due to its... 

Sljukic B, Bank CE, Compton RG (2005) Exploration of stable sonoelectrocatalysis for the electrochemical reduction of oxygen. Electroanalysis 17 1025-1034... 

The catalytic layer of the air electrode is made from a mixture of the same hydrophobic material and porous catalyst [2]. It comprises hydrophobic zones through which the oxygen is transported in gas phase and zones containing catalyst where the electrochemical reduction of oxygen is taking place. It must be noted that the overall structure of the electrode is reproducible when various kinds of carbon-based catalysts are used. 

One of the main problems in the development of air gas-diffusion electrodes for metal-air cells is to find active and stable catalysts for the electrochemical reduction of oxygen. Carbon-based catalysts are mostly used, because of their highly developed surface area and capability for adsorption of 02, suitable morphology, chemical stability, good electric conductivity and comparatively low price. 

Iliev I., Gamburzev S., Kaisheva A., Gas-diffusion electrodes with transition metal macrocyclic catalysts for electrochemical reduction of oxygen, Proceedings of the 31 ISE Meeting 1980 Sept. 22 - 26, Venice, Italy, Vol. I, p. 286-288. 

The electrochemical reduction of oxygen in dimethylformamide generates oxygen radical-anion. This will abstract a hydrogen atom from the methyl group in a methylpyridine, the process finally leading to the pyridinecarboxyUc acid [219],... 

Figure 1, Polarization curve for the electrochemical reduction of oxygen coupled with the electrochemical oxidation of an unspecified organic impurity O.C, designates the open circuit potentials...

Bromopropylamine was reported to form tetrahydro-l,3-oxazin-2-one in moderate yield when treated with the carboxylating reagent (O2 /C02) formed by the electrochemical reduction of oxygen in acetonitrile in the presence of carbon dioxide <1997JOC6754>. 

The formation of the adsorption complex, which is important for the electrochemical reduction of oxygen, then proceeds in close analogy to the formation of the ethylene-transition-metal complex as shown in Fig. 31. 

Branching mechanisms involve both consecutive and parallel electron transfers. The most important application of the RRDE in this context has been to the electrochemical reduction of oxygen [175], on which a large amount of research has been done. Different mechanistic models give rise to different expressions linking the rate constants, which can be compared with experimental data as in previous sections, the most important is the variation of (iD / h ) with rotation speed. A summary of different models has recently appeared [176] the conclusion of which is that, at platinum, the model of Damjanovic et al. [177] is correct diagnostic criteria to test the model have been developed. 

As shown in Figure 18, the potential is almost proportional to the logarithm of H2 concentration diluted in air. When H2 is diluted in N2, the observed potential corresponds to the electromotive force of a H2-02 fuel cell, and in fact the EMF was as large as about 1.0 V with a theoretical slope of 30 mV/decade, as shown in the same figure. It has been shown that in the case of H2 diluted in air, the following electrode reaction, i.e., electrochemical oxidation of hydrogen (2) and electrochemical reduction of oxygen (3), are important. 

Indeed, the mathematical form of the mixed-potential concept (Bockris, 1954) has been applied to a number of chemical processes which, it has been shown, in fact, consist of two partnered surface electrochemical processes (Spiro, 1984). Thus, energy conversion processes at the surface of mitochondrial cells may involve the electrochemical oxidation of glucose as the anodic reaction and the electrochemical reduction of oxygen as the cathodic (Gutmann, 1985). 

The electrochemical reduction of oxygen 02 + 2HzO + 4cq -> 40H must be a part of metabolism. The path and rate-determining step depend on the substrate and the pH. However, some mechanisms of the 02 reduction reaction involve 02 (a superoxide ) and it has been suggested (Gerschmann, 1986) that the incomplete consumption of this ion in oxygen reduction allows free 02 to accumulate, adsorb on the surface of cells, reach DNA, and cause destruction of part of it, with the resulting cancer, etc. 

The anode exhaust gas is mixed with air, and the nonoxidized components are totally oxidized in a catalytic combustion chamber. Because air is fed in excess, the exhaust gas from the burner still contains a significant amount of oxygen. This gas is then fed to the cathode channel where the electrochemical reduction of oxygen takes place. There, new carbonate ions are produced from carbon dioxide and oxygen according to the backward direction of the following cathode reaction ... 

Just H2O2 is a final product of electrochemical reduction of oxygen that founds a direct confirmation in the experiments. 

Regardless of the specific type of fuel cell, gaseous fuels (usually hydrogen) and oxidants (usually ambient air) are continuously fed to the anode and the cathode, respectively. The gas streams of the reactants do not mix, since they are separated by the electrolyte. The electrochemical combustion of hydrogen, and the electrochemical reduction of oxygen, takes place at the surface of the electrodes, the porosities of which provide an extensive area for these reactions to be catalysed, as well as to facilitate the mass transport of the reactants/products to/from the electrolyte from/to the gas phase. 

Bouwkamp-Wijnoltz, A.L. et ah. On active-site heterogeneity in pyrolyzed carbon-sup-ported iron porphyrin catalysts for the electrochemical reduction of oxygen an in situ Mdssbauer study, J. Phys. Chem. B, 106, 12993, 2002. 

Bouwkamp-Wijnoltz, A.L. et al.. Electrochemical reduction of oxygen an alternative method to prepare active C0N4 catalysts, Electrochim. Acta, 45, 379, 1999. 

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