Accelerated Photocatalytic Carbon Dioxide Reduction and Water Oxidation under Spatial Synergy

Photocatalytic conversion of CO₂ and H₂ O into fuels and oxygen is a highly promising solution for carbon-neutral recycling. Traditionally, researchers have studied CO₂ reduction and H₂ O 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 ZnIn₂ S₄ -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 Cu_Zn 'V_S ⋅⋅V_Zn " defect complexes. FT-IR studies coupled with theoretical calculations reveal the spatially synergistic CO₂ reduction and water oxidation on Cu_Zn 'V_S ⋅⋅V_Zn ", 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 H₂ O oxidation through a combination of experimental and theoretical analyses, providing a fresh insight in optimizing photocatalytic system.