Constructing collaborative interface between Mo2N and NiS as efficient bifunctional electrocatalysts for overall water splitting

• NiS nanocrystals are anchored on porous Mo 2 N surfaces to construct functional heterointerfaces by forming Mo-S bonds. • Mo 2 N/NiS heterointerfaces possess a synergistic effect, which exhibit a much-enhanced electrocatalytic activity for overall water splitting. • In a photovoltaic water splitting system, the Mo 2 N/NiS heterointerfaces achieve a favorable solar-to-hydrogen energy conversion efficiency of 8.4%. Solar-driven electrocatalytic water splitting is a promising technology to produce renewable hydrogen fuel. To accomplish this perspective, it is urgent to exploit high-efficiency and robust bifunctional electrocatalysts. Herein, a hybrid Mo 2 N/NiS heterojunction with synergistic effect is developed as bifunctional electrocatalyst for high-efficiency water splitting in alkaline media. Through high-temperature calcination and in-situ hydrothermal growth process, NiS nanocrystals are successfully anchored on porous Mo 2 N to produce a well-defined heterointerface by forming Mo-S bonds. The optimized Mo 2 N/NiS hybrids exhibit a much-enhanced electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) than that of individual Mo 2 N and NiS in 1.0 M KOH. Moreover, benefitting from the robust chemical stability of Mo 2 N substrate, Mo 2 N/NiS hybrids presents an excellent long-term durability. The density functional theory calculations reveal that the improved HER and OER activities are primarily enabled by the synergistic effect of interface between Mo 2 N and NiS, NiS accelerates the water dissociation while Mo 2 N optimize the intermediates adsorption. When the as-prepared Mo 2 N/NiS heterojunction is used as bifunctional catalysts in a photovoltaic water splitting system, it exhibits a favorable solar-to-hydrogen energy conversion efficiency of 8.4%, which is superior to some of reported noble-metal based catalysts. This work provides a facile and efficient strategy to design and fabricate the bifunctional catalysts for water splitting.