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 Ni 3 S 2 /VS 4 nanohorn array grown on nickel foam (NS-horn/NF) is prepared by a self-driven synthesis strategy. We demonstrate that in-situ generation of VS 4 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 Ni 3 S 2 and VS 4 , 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 VS 4 , 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.