Electroreduction of Dioxygen on Polycrystalline Platinum in Alkaline Solution II. Platinum Surface Modified by Hydrogen Evolution

Abstract

A study of the electroreduction of (ORR) in 1 M NaOH on a polycrystalline platinum surface pretreated by evolution at −250 mV in deaerated for 10 min was carried out. As a consequence of this treatment, the Pt surface evolves spontaneously with time toward a Nekrasov (N‐Pt) type behavior both in the cathodic and in the anodic scan. We studied the mechanism of the ORR on two N‐Pt surfaces we called A and C. On both surfaces, is reduced to which is then reduced or disproportionated. On surface A, a full N‐Pt type surface, is reduced only below 170 mV and disproportionates above this potential producing that is recycled below 600 mV giving rise to an enhancement of the current above the two‐electron level. disprorportionates on surface C as well, although with a greater rate constant, producing that is also recycled. The details of the electroreduction of and are thoroughly discussed in relation to the surface processes underneath revealed by the characteristic cyclic voltammograms of the two surfaces. © 2000 The Electrochemical Society. All rights reserved.