ELECTRODEPOSITION OF SILVER ON METALLIC AND NONMETALLIC ELECTRODES FROM THE ACIDIC ALUMINUM CHLORIDE-1-METHYL-3-ETHYLIMIDAZOLIUM CHLORIDE MOLTEN-SALT

The electrodeposition of silver was investigated at polycrystalline platinum, gold, and tungsten, and at glassy carbon in the 66.7-33.3 mole percent aluminum chloride-1-methyl-3-ethylimidazolium chloride room temperature molten salt at 40-degrees-C. Of the four materials studied, the silver deposition-stripping process seemed to be the least complex at platinum. In contrast, the bulk deposition of silver at gold appears to be preceded by an underpotential deposition process similar to that seen in aqueous solutions. Large nucleation overpotentials were needed in order to deposit silver on tungsten and glassy carbon. Instantaneous three-dimensional nucleation of silver was found on the former electrode whereas progressive three-dimensional nucleation predominated on the latter. Diffusion-controlled growth of the developing silver nuclei was found at both electrodes. The bulk silver deposition-stripping process proceeds with virtually 100% efficiency at all four of the electrodes tested. The diffusion coefficient for silver(I) in the melt was found to be (1.2 +/- 0.1) X 10(-6) cm2 s-1 at a platinum rotating disk electrode.