No abstract

Owing to unique optical, electronic, and catalytic properties, MoS have received increasing interest in electrochemical water splitting. Herein, few-layered MoWS hollow nanospheres-modified NiS heterostructures are prepared through a facile hydrothermal method to further enhance the electrocatalytic performance of MoS. The doping of W element optimizes the electronic structure of MoS@NiS thus improving the conductivity and charge-transfer ability of MoS@NiS. In addition, benefitting from the few-layered hollow structure of MoWS, the strong electronic interactions between MoWS and NiS and the hierarchical structure of one-dimensional nanorods and three-dimensional Ni foam, massive active sites and fast ion and charge transportation are obtained. As a result, the optimized MoWS@NiS heterostructure (Mo-W-S-2@NiS) achieves an extremely low overpotential of 98 mV for hydrogen evolution reaction and 285 mV for oxygen evolution reaction at 10 mA cm in alkaline electrolyte. Particularly, using Mo-W-S-2@NiS heterostructure as a bifunctional electrocatalyst, a cell voltage of 1.62 V is required to deliver a 10 mA cm water splitting current density. In addition, the electrode can be maintained at 10 mA cm for at least 50 h, indicating the excellent stability of Mo-W-S-2@NiS heterostructure. Therefore, this development demonstrates an effective and feasible strategy to prepare highly efficient bifunctional electrocatalysts for overall water splitting.