The influence of hydrogen partial pressure, current density, and temperature on the anodic oxidation of sorbed H and the anodic generation of sorbed O were determined. Electrode processes were evaluated and separated to give the following quantities: ( a ) the amount of H associated with a Pt surface and its immediate vicinity, ( b ) the extent of reaction of H atoms, absorbed in the metal interior, that migrate to the surface of the metal and are either ionized or react with O atoms, ( c ) the extent of reaction of H 2 from the solution phase, ( d ) the amount of O adsorbed on the Pt surface, and ( e ) the amount of O absorbed in the Pt surface layers (skin). The kinetics of the open‐circuit reaction of galvanostatically determined amounts of sorbed O with H 2 were determined. This investigation showed that absorbed O in Pt significantly affects coulometric measurements at pulse lengths longer than about 1000 µsec. The presence of absorbed O in the Pt can also materially affect the reaction rate of chemisorbed O with H 2 . Under the experimental conditions, transport of reactants on the solution side was fast enough so that diffusion did not limit processes in either the H ionization or O sorption regions. The data indicated that migration of adsorbed species on the Pt surface to active sites was rate controlling in the O sorption region, except in the case of reaction of adsorbed O with H 2 when significant amounts of O were absorbed in the skin of the Pt. In this case the chemical reaction rate between adsorbed O and H 2 was retarded so that this chemical step appeared to be rate determining. Reaction rates of the adsorbed O and H 2 reaction under open‐circuit conditions were determined at varying temperatures, adsorbed and absorbed O concentrations, and H 2 partial pressures.
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Schuldiner et al. (1965) studied this question.