Electrochemistry of indium. Part I. Anodic oxidation of indium in sodium hydroxide solutions

Anodic oxidation of indium at both low and high current densities has been studied in aqueous sodium hydroxide, conditions under which passivation readily takes place. The anodic polarisation occurs in two stages: (i) the formation of indate ions, and (ii) the formation of indium hydroxide. The initial discharge of hydroxide ions governs the overall reaction rate, whilst the formation of InO2– on the electrode, it is suggested, is the rate-determining step. The number of electrons transferred from the electrode was 3.