Abstract
Electrochemically reduced iron was first anodized in a basic solution at potentials in the passive region. The steady‐state passivated iron then was subjected to a single cathodic potential pulse and then was cathodically reduced, in the initial stage of pulsing, the log of response current was linearly related with time at various preanodizing potentials. This relationship held at each temperature, but the slope depended on the solution temperature and the preanodizing potential. The shape of the cathodic reduction curve and the amount of charge needed for reduction were approximately the same whether or not the cathodic potential pulse was applied before cathodic reduction. Experimental results support the premise that cathodic potential pulsing does not influence the so‐called bulk oxide but only the surface of passivated iron. In particular, the adsorbed oxygen on passive iron is influenced by the pulsing. The response current is explained by the cathodic reduction of adsorbed oxygen. Various kinetic parameters for the reduction reaction of adsorbed oxygen under cathodic pulsing were estimated from the experimental results, and it was found that appreciable coverage on passive iron by adsorbed oxygen appeared only at potentials far more noble than those in the Flade region.