Few-Layered Mo_{(1–<i>x</i>)}W<i>_x</i>S₂ Hollow Nanospheres on Ni₃S₂ Nanorod Heterostructure as Robust Electrocatalysts for Overall Water Splitting

Abstract

Owing to unique optical, electronic, and catalytic properties, MoS 2 have received increasing interest in electrochemical water splitting. Herein, few-layered Mo (1– x ) W x S 2 hollow nanospheres-modified Ni 3 S 2 heterostructures are prepared through a facile hydrothermal method to further enhance the electrocatalytic performance of MoS 2 . The doping of W element optimizes the electronic structure of MoS 2 @Ni 3 S 2 thus improving the conductivity and charge-transfer ability of MoS 2 @Ni 3 S 2 . In addition, benefitting from the few-layered hollow structure of Mo (1– x ) W x S 2, the strong electronic interactions between Mo (1– x ) W x S 2 and Ni 3 S 2 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 ) W x S 2 @Ni 3 S 2 heterostructure (Mo-W-S-2@Ni 3 S 2 ) 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@Ni 3 S 2 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@Ni 3 S 2 heterostructure. Therefore, this development demonstrates an effective and feasible strategy to prepare highly efficient bifunctional electrocatalysts for overall water splitting.