Formation of hierarchical Ni3S2 nanohorn arrays driven by in-situ generation of VS4 nanocrystals for boosting alkaline water splitting

The synergistic achievement of geometric optimization and surface/interfacial modulation of electrocatalysts for booting the overall efficiency of water splitting is highly desirable yet challenging. Herein, a novel hierarchical Ni3S2/VS4 nanohorn array grown on nickel foam (NS-horn/NF) is prepared by a self-driven synthesis strategy. We demonstrate that in-situ generation of VS4 in the NS-horn/NF not only triggers the formation of such unique hierarchical architecture, but favors the graft of enriched active bridging S-2(2-) on the strong coupling interface between Ni3S2 and VS4, and thus the enhanced HER kinetics. More importantly, the abundant active nickel oxides for the OER availably form on the interface benefiting from the surface reconstruction of NS-horn/NF due to the partial leaching of vanadium (IV) of VS4, which promotes the adsorption of OH(-)and leads to the fast OER rate-determining step in alkaline media. When employed to assemble an alkaline electrolyzer as both anode and cathode, NS-horn/NF electrode only needs a small voltage of 1.57 V to yield 10 mA cm(-2) and retains this activity for at least 70 h. Our findings put forward fresh insights into the rational design of highly efficient bifunctional electrocatalysts toward water spitting for next-generation energy conversion and storage devices.