Redox bifunctional activities with optical gain of Ni3S2 nanosheets edged with MoS2 for overall water splitting

Abstract

Exploring cost-efficient catalysts with bifunctional activities of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) holds practical significance for overall water splitting. Herein, for the first time, we report a unique lateral heterostructure of ultrathin Ni3S2 nanosheets (NSs) edged with MoS2 as an efficient and durable bifunctional catalyst for overall water splitting in alkaline media. Benefiting from maximizing functional Mo-S-Ni interfaces that favor the chemisorption of hydrogen and oxygen-containing intermediates, the resultant Ni3S2/MoS2 (NiMoS) catalyst exhibits respectively low overpotentials of 78 and 260 mV at 10 mA cm−2 for HER and OER, superior to the commercial benchmarks (IrO2 and Pt/C), ranking among the best records reported to date. In particular, the NiMoS catalyst renders an attractive light-enhanced effect on both HER and OER activities due to photogenerated charge transfer at Mo-S-Ni interface towards redox kinetic acceleration. An assembled two-electrode alkaline electrolyzer using NiMoS as bifunctional catalysts can deliver a current density of 10 mA cm−2 at low cell voltage of 1.53 V (1.50 V under 1 sun irradiation) with remarkable stability for over 100 h, demonstrating the robust overall water splitting with accessible solar integration.