ELECTROREDUCTION OF INDIUM(III) AT VARIOUS ELECTRODES IN TARTRATE ELECTROLYTES

Electrodeposition of indium at copper, pyrographite, and indium from t artrate electrolytes is studied by the voltammetry, cyclic voltammetry , and rotating disk electrode techniques. The reaction In(III) --> In( O) at pyrographite is shown to occur with greater overvoltage than tha t at indium and copper. The In(III) electroreduction is diffusion-cont rolled. At large concentrations (> 0.088 M), the process shifts into t he kinetic region. The processes of electroreduction of indium ions at copper, pyrographite, and indium electrodes are shown to be similar i n general; however, the nature of oxidation of the indium cathodic dep osit depends on the electrode material. The latter difference may be a ttributed to formation of an alloy or chemical compound of copper and indium at the copper surface at the onset of electrolysis, which assur es strong adhesion between the deposit and copper substrate.