Single-atom Pt–N4 active sites anchored on porous C3N4 nanosheet for boosting the photocatalytic CO2 reduction with nearly 100% CO selectivity

Photoreduction of CO₂ and H₂O into fuels and value-added chemicals is a promising green technology for solar-to-chemical conversion. However, improving the conversion efficiency with regulated product selectivity is a big challenge due to the sluggish dynamic transfer and insufficient active sites. Herein, we report on Pt single atoms anchored porous C₃N₄ nanosheet photocatalyst (Pt₁@CN) with Pt–N₄ coordination for stable and efficient CO₂ photoreduction using H₂O as reductant. The Pt₁@CN exhibits an evolution rate of 84.8 μmol g⁻¹ h⁻¹ with nearly 100% CO selectivity, outperforming most previous C₃N₄-based single-atom photocatalysts. Experimental and DFT calculation results reveal that the Pt–N₄ coordinated active sites promote the photogenerated electron transfer, CO₂ adsorption/activation, *COOH generation, and *CO desorption, thus accounting for the significantly improved CO₂ photoreduction activity with ∼100% CO selectivity. This study provides a deep insight into the significant roles of single-atom active sites in enhancing the CO₂ photoreduction activity and regulating the product selectivity.