Dual-Site Assisted Efficient Alkaline Hydrogen Evolution Reaction on NiS/VS₂@NF

Engineering non-noble metal heterostructure interfaces with multiple active sites is a promising strategy to overcome scaling relationships and enhance multistep reactions. Herein, a dual-site heterogeneous catalyst of NiS/VS₂@NF is developed by wrapping VS₂ on NiS bacillar structures supported on nickel foam, which promotes alkaline hydrogen evolution reaction (HER) at high current densities. In situ spectroscopic analysis and theoretical calculations revealed that strong interaction of V and Ni at the interface generates a distinctive electronic environment where both metal sites facilitate water adsorption, electron-deficient V sites expedite water dissociation, electron-rich Ni sites promote OH desorption, and V and Ni sites together help to streamline hydrogen coupling and the subsequent release via the Volmer-Heyrovsky pathway. The as-prepared NiS/VS₂@NF requires only 222 and 279 mV to reach 0.5 and 1 A cm^-2, respectively, in 1 m KOH, and exhibits negligible change in current density over 140 h of continuous operation at -0.2 V_RHE. This performance is not only better than that of Pt/C@NF, but also surpasses most of the recently reported transition metal sulfide-based materials. This work offers critical insights into designing advanced catalysts for high-performance alkaline HER and understanding their mechanism, with implications extending to a broad range of electrochemical applications.