Engineering defects and adjusting electronic structure on S doped MoO₂ nanosheets toward highly active hydrogen evolution reaction

The electrocatalytic hydrogen evolution reaction (HER) is one of the most promising ways for low-cost hydrogen production in the future. In this work, hetero S atoms were introduced into the MoO₂ to enhance the catalytic activity by simultaneously adjusting electron structure, engineering lattice defect, and increasing oxygen vacancies. And the S doped MoO₂ nanosheets with proper S doping amount show the enhanced performance for HER. The optimized catalyst shows a small onset overpotential as low as 120 mV, a low overpotential of 176 mV at the current density of 10 mA/cm² which is decreased 166 mV compared to that of the pristine MoO₂ nanosheets, a low Tafel slope of 57 mV/decade, and a high turnover frequency of 0.13 H₂/s per active site at 150 mV. This finding proposes an effective strategy to prepare nonprecious metal oxide catalyst for enhancing HER performance by rationally doping hetero atoms.