Electrodeposition of palladium-tin alloys from 1-ethyl-3-methylimidazolium chloride-tetrafluoroborate ionic liquid for ethanol electro-oxidation

Electrodeposition of palladium-tin alloys from 1-ethyl-3-ethylimidazolium chloride-tetrafluoroborate ionic liquid was studied at 120°C. Sn(II) chloride reacts spontaneously with Pd(II) chloride, producing Sn(IV) and Pd nanoparticles. Solutions containing Sn(IV) and Pd(II) were used for potentiostatic electrodeposition of Pd-Sn. The composition of the Pd-Sn electrodeposits varied with the solution composition and deposition potential. Different alloy phases were observed with X-ray diffraction measurements. Whereas the Pd-rich Pd-Sn solid solution deposits are composed of compact nodules, the Sn-rich intermetallic Pd-Sn deposits are composed of polyhedral crystals of various phases. Compared to Pd-coated electrodes, Pd-Sn solid-solution-coated electrodes show enhanced ethanol electro-oxidation efficiency and stability in alkaline aqueous solutions. As Sn content increased, new Pd/Sn intermetallic phases formed, resulting in reduced catalytic efficiency for ethanol oxidation.