Mo doping engineering induced sulfur vacancies of WS2 for electrochemical performance: Implications for hydrogen evolution reaction

Herein, we report a facile cetyltrimethylammonium bromide (CTAB)-assisted strategy for continuous synthesis of ternary Mo x W 1-x S 2 composites with tunable Mo/W ratios. CTAB facilitates the exposure of active sites by suppressing clustering at the molecular scale and expanding the (002) interlayer spacing in WS 2 . Meanwhile, Mo-doping not only optimizes the structure but also introduces sulfur vacancies (V S ), which can effectively modulate the band structure and charge distribution. The hydrogen evolution reaction (HER) of Mo x W 1-x S 2 has been flexibly controlled via defect and doping engineering. Mo-doping activates the basal plane of 2H-WS 2 and supplies more active sites, resulting in higher performance for HER. Electrochemical characterization confirms the significant contributions of Mo-doping to the expansion of electrochemical active surface area (C dl = 27 mFcm −2 ) and the reduction in charge transfer resistance (R ct = 11.8 Ω). The HER activity of 2H-WS 2 has been effectively activated at the Mo-doping content of 5%. Density functional theory was employed to investigate the charge distribution and electronic structure induced by V S of Mo x W 1-x S 2 , revealing that the enhanced catalytic activity of 2H-phase MoWS 2 stems from electron donation by V S . This study provides a new strategy for the structural design and efficient synthesis of 2H-phase catalysts.