Interfacial electronic modulation of Ni3S2 nanosheet arrays decorated with Au nanoparticles boosts overall water splitting

Abstract Rationally design and exploration of bifunctional electrocatalysts with excellent performance towards water splitting is significant for hydrogen energy economy. Herein, a novel Au/Ni3S2 heterostructure catalyst that was composed of self-supported Ni3S2 nanosheets decorated with Au nanoparticles on Ni foam was fabricated. The bifunctional catalyst exhibited excellent catalytic activities towards oxygen evolution reaction (230 mV @ 10 mA cm−2) and hydrogen evolution reaction (97 mV @ 10 mA cm−2) in 1 M KOH. The electrolytic tank using the bifunctional catalyst only required 1.52 V to deliver 10 mA cm−2 and sustained for 60 h, outperforming most of advanced bifunctional catalysts. The X-ray absorption fine structure (XAFS) and density functional theory (DFT) calculations validated that the strong electronic coupling at the interface could modulate the electronic structure of Ni3S2, thereby optimizing the free energies of the adsorbed intermediates. This work provides an atomic-scale insight into the structure-properties relation of a promising heterostructure catalyst for water splitting.