Highly Asymmetric CuSA‐Ov‐Ti3c Atomic Sites Catalyst for Unprecedented Solar Hydrogen Generation

Abstract Atomic‐level tailoring of active sites is an efficient strategy for designing high‐performance photocatalysts for clean energy. Asymmetric atomic sites (AAS) like M SA ‐O v ‐M 2 created through hetero‐metal single atoms (M SA ) doping on defect‐rich metal oxides (M 2 ‐O v ‐M 2 ) are favored for better activation of targeted molecules. However, creating AAS typically demands high energy input, hindering their widespread use in photocatalytic H 2 production. Furthermore, precise control over surface defects to create AAS remains challenging. Here, Cu SA ‐O v ‐Ti 3c highly asymmetric atomic sites catalyst (HAASC) is constructed by strategically trapping Cu single atoms on high‐index (111) faceted TiO 2 . This material combines single‐atom catalysis and facet engineering, achieving unprecedented H 2 production rates (8.3 mmol h −1 g −1 in pure water and 784.5 mmol h −1 g −1 in water/methanol mixture). Experimental and theoretical analyses reveal Cu SA substituting five‐coordinated Ti atoms (Ti 5c ) next to three‐coordinated (Ti 3c ) ones, forming Cu SA ‐O v ‐Ti 3c HAAS. HAAS plays multiple roles in i) improving light harvesting, charge‐transfer dynamics, and redox capability of photoexcited electrons; ii) enhanced adsorption and polarization of H 2 O molecules; iii) facilitating electron transfer from Cu SA ‐O v ‐Ti 3c to H 2 O molecules, and iv) raising d‐band center toward Fermi level resulting in ≈250‐fold enhanced H 2 production than Ti 5c ‐O‐Ti 3c AASC. This work opens new avenues for future structural designs in heterogeneous catalysis for energy‐related applications.