Interface engineering: few-layer MoS2 coupled to a NiCo-sulfide nanosheet heterostructure as a bifunctional electrocatalyst for overall water splitting

Abstract

Inexpensive and highly efficient bifunctional electrocatalysts are vital for water splitting. Herein, free-standing heterogeneous MoS₂/NiCoS nanosheets as a bifunctional electrocatalyst for overall water splitting are designed. The abundant heterogeneous interfaces in MoS₂/NiCoS, enriched holes and few-layer structure of MoS₂ can not only provide enriched active sites but also accelerate electron/ion transfer. Consequently, the optimized MoS₂/NiCoS heterostructure achieves a low overpotential of 189 mV for the hydrogen evolution reaction (HER) and 290 mV for the oxygen evolution reaction (OER) at 10 mA cm⁻² in an alkaline electrolyte. In particular, in a two-electrode electrolyzer assembly, the MoS₂/NiCoS heterostructure nanosheets can afford a current density of 10 mA cm⁻² at a voltage of 1.50 V, serving as one of the best water-splitting electrocatalysts to date. This work provides a feasible strategy to construct efficient free-standing heterogeneous bifunctional electrocatalysts for overall water splitting.