Nucleation and growth mechanisms of an electrodeposited Ni-Se-Cu coating on nickel foam

Electrocatalysts for water splitting have been widely explored among recent years. In this study, nickel-selenium-copper (Ni-Se-Cu) coating was synthesized on nickel foam through potentiostatic electrodeposition. The electrochemical kinetics and nucleation mechanisms of the deposition were investigated, and the diffusion coefficient D from different deposition potentials and temperatures was calculated. Results reveal that the electrodeposition of Ni-Se-Cu follows an instantaneous nucleation and diffusion-controlled three-dimensional (3D) growth mechanism. Deposition potential and bath temperature slightly effect the nucleation mechanism of electrodeposition. The apparent activation energy E_a of the hydrogen evolution reaction (HER) in 1.0 M KOH electrolyte of Ni-Se-Cu is 21.1 kJ·mol^-1, which is lower than that of Ni-Se (37.7 kJ·mol^-1). The majority phase formed by nickel and selenium is Ni₃Se₂, and a Ni(Cu) solid solution forms after the incorporation of Cu atoms into a Ni lattice.