Oxygen evolution properties

Luo, J., Zhang, Q., Garcia-Martinez, J. and Suib, S.L. (2008) Adsorptive and acidic properties, reversible lattice oxygen evolution, and catalytic mechanism of cryptomelane-type manganese oxides as oxidation catalysts. Journal of the American Chemical Society, 130, 3198-3207. 

In summary, the results of this investigation indicated that the formal oxidation of the nickel sites in a composite nickel-iron oxyhydroxide modifies the electronic and structural properties of the ferric sites yielding a more d-electron deficient iron species. Although it may be reasonable to suggest that the elec-trocatalytic activity of this composite oxide for oxygen evolution may be related to the presence of such highly oxidized iron sites,... 

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. 

In contriving optimal photosplitting of water, it is desirable to irradiate two photoelectrodes. In considering photoanodes, it is difficult to achieve suitable properties with semiconducting oxides, which tend to be stable under oxygen evolution. On the other hand, arsenides and sulfides appear to have more suitable photoelectrochemical properties, but are clearly unstable when exposed to Oz evolution, (b) What experimental procedures could be used to overcome this difficulty (Bockris)... 

At E > 1.0 V transpassive dissolution as QxCY2 is obtained in 0.5 M H2SO4, with a strong increase of the current density (Fig. 5). At E > 1.7 V oxygen evolution contributes to the large anodic current. These characteristic electrochemical properties indicate the importance of Cr as an alloying additive to obtain corrosion-resistant alloys, especially at negative potentials and in acidic solutions. 

Bockris et al. [87, 290, 291] have recently reported results of a comprehensive program of surface characterization of a large number of perovskite oxide electrodes in oxygen evolution investigations. Anodic and cathodic oxygen reactions were studied in detail as a function of the solid-state surface properties of these materials. Capacity-potential curves were analysed in terms of the Mott-Schottky treatment and indicated that the potential distribution in the oxide corresponds to a depletion of electrons at the oxide electrode surface in the potential region where oxygen reduction... 

In a study of a series of iron-based spinels, Iwakura et al. [313] did not observe a correlation of chlorine evolution overvoltage with the magnetic properties of the oxide. In contrast, a dependence of overpotential on magnetic properties was observed for oxygen evolution. 

---