Accelerated Photocatalytic Carbon Dioxide Reduction and Water Oxidation under Spatial Synergy

Photocatalytic conversion of CO2 and H2O into fuels and oxygen is a highly promising solution for carbon‐neutral recycling. Traditionally, researchers have studied CO2 reduction and H2O oxidation separately, overlooking potential synergistic interplay between these processes. This study introduces an innovative approach, spatial synergy, which encourages synergistic progress by bringing the two half‐reactions into atomic proximity. To facilitate this, we developed a defective ZnIn2S4‐supported single‐atom Cu catalyst (Cu−SA/D−ZIS), which demonstrates remarkable catalytic performance with CO2 reduction rates of 112.5 μmol g−1 h−1 and water oxidation rates of 52.3 μmol g−1 h−1, exhibiting a six‐fold enhancement over D−ZIS. The structural characterization results indicated that the trapping effect of vacancy associates on single‐atom copper led to the formation of an unsaturated coordination structure, Cu‐S3, consequently giving rise to the CuZn′VS⋅⋅VZn“ defect complexes. FT‐IR studies coupled with theoretical calculations reveal the spatially synergistic CO2 reduction and water oxidation on CuZn′VS⋅⋅VZn”, where the breakage of O−H in water oxidation is synchronized with the formation of *COOH, significantly lowering the energy barrier. Notably, this study introduces and, for the first time, substantiates the spatial synergy effect in CO2 reduction and H2O oxidation through a combination of experimental and theoretical analyses, providing a fresh insight in optimizing photocatalytic system. Spatial synergy has been identified as a novel approach to enhance photocatalytic carbon dioxide reduction and water oxidation on defect complexes for the first time. This strategy synchronizes the breakage of O−H bonds in water oxidation and the formation of *COOH in CO2 reduction, effectively promoting both processes.