Mechanism and kinetics of the cathodic reduction of In(III) ions at a gold electrode from concentrated ZnBr 2 solutions

Abstract

The electrodeposition of indium from concentrated aqueous ZnBr 2 solutions of In(III) was investigated employing coulometry, rotating disc and ring-disc electrode voltammetry. With increasing concentration of ZnBr 2, the three-electron wave of the In(III) reduction gradually splits into two waves, which correspond to the In(III)/In(I) and In(I)/In electrode reactions, respectively. The diffusion coefficients of the In(III) and In(I) ions, and the formal potentials and kinetic parameters of the In(III)/In(I) electrode reaction were determined for ZnBr 2 concentrations varying within the range 6.0–9.4 mol dm −3. The stepwise nature of the above-mentioned reaction is discussed.