Electrodeposition and electrocatalytic performance of Pd-Ni alloy films from aqueous solutions for enhanced electrochemical hydrogen evolution

Abstract

Palladium-nickel (Pd-Ni) alloy films were electrodeposited on copper supports. The influence of deposition parameters on the surface morphology and chemical composition of the films was investigated. The surface morphology, chemical composition and elemental states of the films were characterized using scanning electron microscopy, energy-dispersive spectroscopy and X-ray photoelectron spectroscopy, respectively. The electrocatalytic performance of the selected films was evaluated through linear sweep voltammetry, electrochemical impedance spectroscopy and cyclic voltammetry. The results demonstrate that the deposition parameters significantly influenced the deposition rate of the films. The deposition rate increased with the current density, showing a change trend in initially increase and then decrease with the rise in bath temperature and deposition time. The particle size of the film increased with both current density and deposition time. Pd-Ni films exhibited the face-centered cubic structure of polycrystalline phase, the grain size and lattice parameters decreased as the Ni-content increased. Pd₇₈Ni₂₂ film with many spherical particles exhibited good electrocatalytic activity in alkaline solution, requiring only the overpotential of 162 mV to achieve a current density of 10 mA·cm⁻², which demonstrated a low Tafel slope of 47.6 mV·dec⁻¹ and an exchange current density as high as 0.326 mA·cm⁻².