Chloride-ion effects on the reversible and irreversible surface oxidation processes at Pt electrodes, and on the growth of monolayer oxide films at Pt

Abstract

By means of cyclic-voltammetry experiments conducted at Pt electrodes in 6 mol dm^–3 H₂SO₄ and HClO₄ at low (213 K) temperature, the effects of Cl^– on the resolvable reversible and irreversible stages of Pt surface oxide formation and reduction have been evaluated in relation to the competition between anodic deposition of OH and O species and specific adsorption of Cl^– at Pt surfaces at potential > ca. 0.8 V E_H.

Cl^– effects on the logarithmic growth of the monolayer surface oxide film with time have also been investigated.

Both types of effects are discussed in terms of the tendency of adsorbed Cl^– ion to promote place-exchange reconstruction of the OH/O monolayer on Pt-electrode surfaces. The observed effects of Cl^– are of interest in the kinetic behaviour of the anodic Cl₂ evolution reaction at oxidized Pt-electrode surfaces where the electrocatalytic properties of the interface depend on the state of the oxide film with co-adsorbed Cl^– ion present in it.