Structural design strategy improving catalytic activity of binary metal sulfides interface for efficient water splitting electrocatalysts

The use of efficient and economical electrocatalysts is essential to facilitate hysteretic kinetics throughout the water-splitting process. This paper presents a strategy for the in-situ conversion of NiMoO4 to needle-like NiS2-MoS2 heterojunction structures on reduced graphene oxide-modified nickel foam substrates (rGO/NF) via a one-step vulcanization method. Theoretical calculations reveal that charge engineering modulation of dissipation and accumulation of electrons at the NiS2 and MoS2 heterogeneous interface optimizes the reaction sites and d-band centers away from the Fermi energy level, improving the intrinsic catalytic activity. As expected, NiS2-MoS2/rGO/NF catalysts with rich heterogeneous interfaces, abundant defects, fully exposed active sites, and electronic interactions exhibit excellent activity in oxygen evolution reactions (OER) and hydrogen evolution reactions (HER), specifically, at overpotentials of 210 and 103 mV, reaching 10 mA cm−2 for OER and more importantly, when used as both cathode and anode for overall water separation, a low cell voltage of 1.52 V is required to achieve a current density of 10 mA cm−2, which is considerably better than other bifunctional electrocatalysts.