Characterization of electrocatalysis in the oxygen evolution reaction at platinum by evaluation of behavior of surface intermediate states at the oxide film

The anodic O{sub 2} evolution reaction (OER) at noble-metal anodes provides an important case of electrocatalysis where the electrode surface on which the reaction proceeds depends on potential, through the state of the surface of a thin oxide film developed upon it. An essential but little examined aspect of electrocatalysis is the behavior of the kinetically involved intermediates of the reaction at the electrode's surface in relation to the potential dependence of the electrode reaction rate, characterized by the Tafel slope. Digitally recorded potential relaxation transients following current interruption are used, as in our previous studies on cathodic H{sub 2} evolution, to evaluate the pseudocapacitance (C{sub {var phi}}) of intermediates generated in the steady state of the OER at Pt and hence the potential dependence of coverage by the kinetically significant intermediate states in the reaction.