Few-Layered Mo(1-x)WxS2 Hollow Nanospheres on Ni3S2 Nanorod Heterostructure as Robust Electrocatalysts for Overall Water Splitting.

Owing to unique optical, electronic, and catalytic properties, MoS2 have received increasing interest in electrochemical water splitting. Herein, few-layered Mo(1-x)WxS2 hollow nanospheres-modified Ni3S2 heterostructures are prepared through a facile hydrothermal method to further enhance the electrocatalytic performance of MoS2. The doping of W element optimizes the electronic structure of MoS2@Ni3S2 thus improving the conductivity and charge-transfer ability of MoS2@Ni3S2. In addition, benefitting from the few-layered hollow structure of Mo(1-x)WxS2, the strong electronic interactions between Mo(1-x)WxS2 and Ni3S2 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 Mo(1-x)WxS2@Ni3S2 heterostructure (Mo-W-S-2@Ni3S2) achieves an extremely low overpotential of 98 mV for hydrogen evolution reaction and 285 mV for oxygen evolution reaction at 10 mA cm-2 in alkaline electrolyte. Particularly, using Mo-W-S-2@Ni3S2 heterostructure as a bifunctional electrocatalyst, a cell voltage of 1.62 V is required to deliver a 10 mA cm-2 water splitting current density. In addition, the electrode can be maintained at 10 mA cm-2 for at least 50 h, indicating the excellent stability of Mo-W-S-2@Ni3S2 heterostructure. Therefore, this development demonstrates an effective and feasible strategy to prepare highly efficient bifunctional electrocatalysts for overall water splitting.