ABSTRACT Recent studies have indicated that the heterovalent states and vacancy defect structures in bimetallic oxysulfide play a crucial role in pollutant reduction reactions. However, systematic investigations into the synergistic coupling between heterovalent states and vacancy defect structures during the photocatalytic hydrogen evolution reaction (PHER) remain scarce. Herein, a tungsten/oxygen (W/O) co‐doped Ag 2 S bimetallic oxysulfide (AgWOS) with heterovalent W 5+ /W 6+ states and sulfur vacancy (Vs) defects was synthesized via a facile thermohydrolysis method. The combination of W‐doping and hydrazine‐driven conditions induces abundant Vs defects, which act as active sites for water adsorption and activation, thereby facilitating proton generation in the PHER process. Moreover, the hydrazine‐driven condition promotes the formation of heterovalent W 5+ /W 6+ states, which provide efficient electron transfer channels between W 5+ and W 6+ to boost PHER performance. The optimized AgWOS‐2 with a balanced heterovalent n (W 5+ )/ n (W 6+ ) ratio and a high concentration of Vs achieves an impressive PHER rate of 1074.2 µmol·h −1 and an apparent quantum efficiency of 6.21% at 420 nm in pure water. Density functional theory calculations reveal that the synergy between heterovalent states and vacancy defects lowers the water dissociation barrier, accelerates *H generation, and boosts electron transfer between W 5+ and W 6+ . Moreover, S‐3 p and O‐2 p orbital hybridization suppresses photocorrosion and improves catalyst stability, enabling AgWOS‐2 to retain 91.6% of its initial PHER activity after ten cycles. This study elucidates the synergistic interaction mechanism between heterovalent states and vacancy defects in a bimetallic oxysulfide, offering valuable insights for the rational design of efficient and durable PHER catalysts.
Yang et al. (Thu,) studied this question.