Electrocatalysis oxygen evolution

A Specific Example of Electrocatalysis Oxygen Evolution on Perovskites... 

At IREQ, besides the participation in the field tests run by the engineers of Hydro-Quebec (12), the main effort has been to tackle fundamental problems in the field of electrocatalysis (18-22) and of anodic oxidation of different potential fuels (23-26). A careful and extensive study of the electrochemical properties of the tungsten bronze has been carried out (18-20) the reported activity of these materials in acid media for the oxygen reduction could not be reproduced and this claim by other workers has been traced back to some platinum impurities in the electrodes. Some novel techniques in the area of electrode preparation are also under study (21,22) the metallic deposition of certain metals on oriented graphite show some interesting catalytic features for the oxygen reduction and also for the oxygen evolution reaction. 

Pt is, of course, not a good electrocatalyst for the O2 evolution reaction, although it is the best for the O2 reduction reaction. However, also with especially active oxides of extended surface area, the theoretical value of E° has never been observed. For this reason, the search for new or optimized materials is a scientific challenge but also an industrial need. A theoretical approach to O2 electrocatalysis can only be more empirical than in the case of hydrogen in view of the complexity of the mechanisms. However, a chemical concept that can be derived from scrutiny of the mechanisms mentioned above is that oxygen evolution on an oxide can be schematized as follows [59] ... 

B. Electrocatalysis of Oxygen Evolution in Advanced Alkaline Water Electrolysis... 

Electrocatalysis of the Anodic Oxygen Evolution by Raney-Nickel Coatings... 

Comninellis C, De Battisti A. Electrocatalysis in anodic oxidation of organics with simultaneous oxygen evolution. J Chim Phys 1996 93 673-679. 

The first step was the evolution away from the Schottky barrier model of photoelectrochemistry caused by the evidence from the late 1970s onward that the rate of photoelectrochemical reactions was heavily dependent on surface effects (Uosaki, 1981 Szklarczyk, 1983). This was followed by the use of both a photocathode and a photoanode in the same cell (Ohashi, 1977). Then the use of nonactive thin protective passive layers of oxides and sulfides allowed photoanodes to operate in potential regions in which they would otherwise have dissolved (Bockris and Uosaki, 1977). The final step was the introduction of electrocatalysis of both hydrogen and oxygen evolution by means of metal islets of appropriate catalytic power (Bockris and Szklarczyk, 1983). 

In this chapter, the focus will be on trends in electrocatalysis of the water-splitting reaction or the oxygen evolution reaction (OER), which is the reaction at the anode side in an electrolysis cell. Furthermore, simple framework for addressing OER applying DFT simulations will be presented. For further reading, there are two previous book chapters where the approach has been reviewed [3, 4],... 

Man IC, Su H-Y, Calle-Vallejo F. et al. Universality in Oxygen Evolution Electrocatalysis on Oxide Surfaces. ChemCatChem 2011 3 1159-65. 

XVII. Electrocatalysis and Kinetic Behavior of Oxygen Evolution Reaction... 

S. Trasatti, Electrode kinetics and electrocatalysis of hydrogen and oxygen electrode reactions. 4. The oxygen evolution reaction, in Electrochemical Hydrogen Technologies (Ed. H. Wendt), Elsevier, Amsterdam, 1990, pp. 104-135. 

The data summarized in this paper have established that the oxide pyrochlores under discussion substantially reduce the activation energy overvoltages associated with oxygen electrocatalysis. Specifically, it is found that these catalysts, in aqueous alkaline media near ambient temperature, are superior to any other oxygen evolution catalyst and are equal in performance to the best known oxygen reduction catalysts. As bidirectional oxygen electrocatalysts, they appear to be unmatched. 

Until now, the methodology available to study charge transfer reactions at soft interfaces has been rather mature, and studies in the field have shifted to the study of catalyzed reactions such as the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), or even oxygen evolution reaction (OER). Eor this, two classes of catalysts have been used (i) molecular catalysts and (ii) nanoparticle solid catalysts. These two approaches draw their inspiration from classical molecular catalysis and from electrocatalysis, respectively. 

The difference between the low overpotential for chlorine and the high overpotential for oxygen avoids a significant oxygen evolution. DS A today can be used for more than 8 years before the coating has to be regenerated. For details of DSA, see essay Electrocatalysis of Chlorine Evolution. ... 

However, the electrochemical oxygen evolution reaction (OER) from the water in acid solutions is thermodynamically slightly more favorable than the CER given by Eq. 2 (the fP value for the OER is 1.229 V). Bearing in mind that electrocatalysis essentially implies the activity and selectivity of various electrode materials toward a certain electrode reaction [2], the correct choice of electrode material that is of high electrocatalytic activity for the CER and of lower activity for the OER is of extreme importance. Anyhow, CAT is always subjected to current loss due to the OER as a side reaction. This fact sets additional demands toward the anode material for the CER, i.e., its stability toward the OER and consequently its durability in CAT. 

Singh RN, Hamdani M, Koenig JF, Poillerat G, Gautier JL, Chartier P (1990) Thin films of C03O4 and NiCo204 obtained by the method of chemical spray pyrolysis for electrocatalysis III. The electrocatalysis of oxygen evolution. J Appl Electrochem 20 442-446... 

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