Electrochemical studies of the Ag2O/AgO phase change in alkaline solutions

Abstract

The anodic oxidation of Ag₂O to AgO in potassium hydroxide solution has been investigated by controlled potential oxidations at 25°C. Separate Ag/Ag₂O electrodes of fixed electrochemical capacity were oxidized at controlled potential using steps of 20 mV over a range of 300 mV and the corresponding current-time curves were recorded. By correlating the structure of the deposit with the kinetic studies the growth geometry and nucleation law for the oxidation of Ag₂O deposits in alkaline solutions were determined. The oxidation of Ag₂O to AgO involves the progressive nucleation of AgO centres coupled with three-dimensional growth. A mechanism for lattice formation is proposed based on the concentration and potential dependence of the rate of crystal growth.