Electrodeposition of Pd alloys from choline chloride/urea deep eutectic solvents

In this study, the electrodeposition of palladium alloys was investigated in a choline chloride/urea based deep eutectic solvent containing sulfosalicylic acid dihydrate as organic additive and Pd(II) + Ag(I), Pd(II) + Pt (II), or Pd(II) + Pt (II) + Ag(I) as metal components. The electrochemical behavior of the electrolytes was characterised by cyclic voltammetry. The electrodeposition processes require nucleation overpotential. Energy-dispersive X-ray data indicated that the layer thickness and composition of the produced Pd–Ag, Pd–Pt, and Pd–Pt–Ag films could be varied by changing the deposition mode. Additions of Ag(I) to the Pd and Pd–Pt electrolytes enhanced the overall metal deposition rate. Scanning electron micrographs of the electrodeposits showed that in general, the Pd alloys deposited by pulse current were nodular and relatively compact, whereas the films deposited by potentiostatic deposition were less dense and covered with dendrite-like and sharp-edged crystallites. Data collected from X-ray diffraction (XRD) experiments proved the existence of metallic alloys.