Reversible active bridging sulfur sites grafted on Ni₃S₂ nanobelt arrays for efficient hydrogen evolution reaction

Elaborate and rational design of cost-effective and high-efficiency non-noble metal electrocatalysts for pushing forward the sustainable hydrogen fuel production is of great significance. Herein, a novel VS₄ nanoparticle decorated Ni₃S₂ nanobelt array in-situ grown on nickel foam (VS₄/Ni₃S₂/NF NBs) was prepared by a self-templated synthesis strategy. Benefitting from the unique nanobelt array structure, abundant highly active bridge S₂^2- sites and strong electronic interaction between VS₄ and Ni₃S₂ on the heterointerface, the integrated VS₄/Ni₃S₂/NF NBs exhibited excellent electrocatalytic hydrogen evolution activity and robust stability. The density functional theory (DFT) further revealed the reversible conversion catalysis mechanism of bridging S₂^2- sites in VS₄/Ni₃S₂/NF NBs during HER process. Notably, bidentate bridging SS bonds as the predominant catalytically active centers can spontaneously open once H adsorbed its surface, leading to the aggregation of negative charges on S atoms and thus facilitating the generation of H* intermediates, and spontaneously close when H* desorption is going to form H₂. Our work provides fresh insights for developing potential polysulfides as high-performance hydrogen-evolving electrocatalysts for prospective clean energy production from water splitting.