Electrodeposition of palladium-silver in a Lewis basic 1-ethyl-3-methylimidazolium chloride-tetrafluoroborate ionic liquid

摘要

The electrodeposition of palladium-silver alloys was investigated in a basic 1-ethyl-3-methylimidazolium chloride/tetrafluoroborate ionic liquid containing Pd(II) and Ag(I). Cyclic voltammetry experiments showed that the reduction of Ag(I) occurs prior to the reduction Pd(II) Both electrodeposition processes require nucleation overpotential. Energy-dispersive spectroscopy data indicated that the composition of the Pd-Ag alloys could be varied by deposition potential and concentrations of Pd(II) and Ag(I) in the solution. The Pd content in the depositec Pd-Ag alloy increased with decreasing deposition potential and the Pd mole fraction in the plating bath. At potentials where the deposition ol both Pd and Ag was mass-transport limited, the Pd/Ag ratio in the electrodeposited alloys was slightly less than the Pd(II)/Ag(I) ratio in the ionic liquid due to the smaller diffusion coefficient of Pd(II). Scanning electron micrographs of the electrodeposits showed that in general the Pd-Ag alloys were nodular and become more compact upon increasing the temperature up to 120 ℃.