Electrochemical study of the properties of indium in room temperature chloroaluminate molten salts

The electrochemistry of indium was studied with voltammetry and chronoamperometry at glassy carbon, tungsten, and nickel electrodes in the basic and acidic aluminum chloride-1,2-dimethyl-3-propylimidazolium chloride molten salt at 27°C. In the basic melt, In(III) is complexed as [InCl₅]^2-, which could be reduced to indium metal through a three-electron reduction process. The electrodeposition of indium on glassy carbon and tungsten electrodes involves progressive three-dimensional nucleation on a finite number of active sites with diffusion-controlled growth of the nuclei. The electrodeposition of indium metal on a nickel electrode entails progressive three-dimensional nucleation on a large number of active sites. The formal potentials of the In(III)/In couple in the 44.4 to 55.6 and 49.0 to 51.0 mole percent (m/o) melts are -1.096 and -1.009 V, respectively, vs. Al(III)/Al in the 66.7 to 33.3 m/o.