Electrodeposition of palladium-copper films from 1-ethyl-3- methylimidazolium chloride-tetrafluoroborate ionic liquid on indium tin oxide electrodes

The electrodeposition of palladium-copper alloys in 1-ethyl-3- methylimidazolium chloride-tetrafluoroborate ionic liquid containing excess chloride ions was studied on indium tin oxide (ITO) coated glass electrodes at 120°C. Cyclic voltammogrammetric results indicate that the thermodynamic deposition potential of copper is more negative than that of palladium. The presence of palladium(II) reduces the overpotential required for the deposition of copper. In addition, underpotential deposition of copper on the palladium electrode was observed. In contrast, the presence of copper(II) increases the overpotential required for the deposition of palladium. Palladium-copper coatings were prepared on the ITO electrode by constant potential electrolysis. Scanning electron microscopy results indicate that the deposits had nodular morphologies. Calculations from X-ray powder diffraction data show that the crystal size of the deposit decreased with increasing deposition overpotential. The prepared palladium-copper coatings adhered well on the ITO substrates and showed a good electrocatalytic capability for the electro-oxidation of ethanol in alkaline solution.