Enhanced Synergy of Single Atoms and Engineered Defects Via Chemical Scissors for Photocatalytic Hydrogen Evolution

Titanium dioxide (TiO 2 ) is a promising photocatalyst for hydrogen evolution but suffers from rapid charge recombination and a lack of active sites. Although single‐atom catalysts (SACs) maximize metal atom utilization, their performance is often limited by insufficient anchoring sites on the support. Here, we report a “chemical scissors” strategy to achieve enhanced synergy between palladium (Pd) single atoms and oxygen vacancies (Ov) in TiO 2 through precise control of defect‐mediated anchoring. By selectively etching metallic Pd particles while preserving Pd atoms anchored at oxygen vacancy sites, we successfully constructed a series of Pd 1 /TO‐Ov catalysts with progressively increased single‐atom loadings. Systematic experimental characterizations and density functional theory (DFT) calculations reveal that oxygen vacancies not only serve as preferential anchoring sites (ASs) for stabilizing Pd single atoms, but also enable strong electronic interactions that enhance the intrinsic activity of each isolated metal center. This defect‐engineered synergy optimizes charge separation and maximizes active site utilization. The optimized Pd 1 /TO‐Ov‐6 catalyst exhibits a remarkable hydrogen evolution rate of 5656.67 µmol g −1 h −1 and a high turnover frequency of 167.2 h −1 . This work provides a rational design strategy for high performance SACs.