Synergistic Effects of Tungsten Doping and Sulfur Vacancies in MoS2 on Enhancement of Hydrogen Evolution

Molybdenum sulfide (MoS2) has extensively attracted attention as a promising nonprecious metal catalyst for the electrochemical hydrogen evolution reaction (HER). Nevertheless, synergistically enhancing the intrinsic conductivity and active sites of MoS2 is the pivotal challenge to build up its hydrogen production performance. Herein, a facile ionic liquid-assisted hydrothermal and subsequent annealing treatment strategy is first reported to synthesize W-doped MoS2 nanosheets supported on carbon cloth (Mo1‑x W x S y /CC). The experimental results prove that the substitutional W doping can effectively activate the catalytic activity of the inert basal plane of MoS2 due to the generation of sulfur vacancies. Density functional theory calculations further confirm that W doping and S vacancies reduce the band gap of MoS2 and promote the adsorption of H atoms, thereby greatly improving the HER performance. The synergistic effects of W doping and S vacancies endow this material remarkable HER performance with a low Tafel slope of 49.3 mV dec–1 and an overpotenial of 165 mV for 10 mA cm–2 in 0.5 M H2SO4 solution. In short, our new strategy provides a simple and efficient pathway to synthesize Mo1‑x W x S y /CC, and it can be applied to the design of other materials possessing multifarious merits.