Few-Layered MoWS Hollow Nanospheres on NiS Nanorod Heterostructure as Robust Electrocatalysts for Overall Water Splitting.

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.