P-Mediated Cu-N₄ Sites in Carbon Nitride Realizing CO₂ Photoreduction to C₂ H₄ with Selectivity Modulation

Photocatalytic CO₂ reduction to high value-added C₂ products (e.g., C₂ H₄ ) is of considerable interest but challenging. The C₂ H₄ product selectivity strongly hinges on the intermediate energy levels in the CO₂ reduction pathway. Herein, Cu-N₄ sites anchored phosphorus-modulated carbon nitride (CuACs/PCN) is designed as a photocatalyst to tailor the intermediate energy levels in the the C₂ H₄ formation reaction pathway for realizing its high production with tunable selectivity. Theoretical calculations combined with experimental data demonstrate that the formation of the C-C coupling intermediates can be realized on Cu-N₄ sites and the surrounding doped P facilitates the production of C₂ H₄ . Thus, CuACs/PCN exhibits a high C₂ H₄ selectivity of 53.2% with a yielding rate of 30.51 µmol g^-1 . The findings reveal the significant role of the coordination environment and surrounding microenvironment of Cu single atoms in C₂ H₄ formation and offer an effective approach for highly selective CO₂ photoreduction to produce C₂ H₄ .