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 Ea 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.

Novel heterostructure Cu2S/Ni3S2 coral-like nanoarrays on Ni foam to enhance hydrogen evolution reaction in alkaline media.

Exploring efficient alternatives to precious noble metal catalysts is a challenge. Here, a new type of non-noble metal Cu2S/Ni3S2 heterostructure nanosheet array is fabricated on 3D Ni foam. This electrocatalyst has excellent activity and durability to Hydrogen Evolution Reaction (HER) under alkaline conditions. The synergistic catalysis produced by the {2̄10} and (034) crystal planes and the increase in charge transfer and the number of active sites caused by lattice defects greatly improve the electrocatalytic activity of Ni3S2. In the HER process, the Cu2S/Ni3S2 interface increases the formation of S-H bonds, and Cu2S promotes the transformation during the HER process into S-doped CuO, optimizing the adsorption capacity of S-doped sites for H. Among electrocatalysts made with different feed ratios, Cu2S/Ni3S2/NF-3, for HER, only needs an overpotential of 50 mV to deliver a current density of 10 mA cm-2. This work provides a promising non-noble metal electrocatalyst for water splitting under alkaline conditions.

Potentiostatic electrodeposition of Ni-Se-Cu on nickel foam as an electrocatalyst for hydrogen evolution reaction.

Development of cost-effective and efficient earth-abundant catalysts for hydrogen evolution reaction (HER) is a great challenge. In this study, by one-step potentiostatic electrodeposition, the Ni-Se-Cu electrocatalyst on nickel foam was fabricated as a binder-free HER electrocatalyst. As compared with Ni-Se electrocatalysts, such fabricated Ni-Se-Cu electrocatalyst exhibited prominent electrocatalytic activity to the HER in alkaline electrolyte. This Ni-Se-Cu electrocatalyst exhibits a small overpotential of 136 mV to achieve a current density of 10 mA·cm-2 and high electrochemical stability. The remarkable HER properties of Ni-Se-Cu electrocatalyst mainly originate from high electronic conductivity induced by Cu-doping. This work shows a cheap and simple avenue to develop high efficient non-noble electrochemical electrocatalysts for HER.