Synergistic Effects of Tungsten Doping and Sulfur Vacancies in MoS₂on 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 (Mo_1-xW_xS_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 Mo_1-xW_xS_y/CC, and it can be applied to the design of other materials possessing multifarious merits.