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

Photoreduction of CO 2 and H 2 O 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 C 3 N 4 nanosheet photocatalyst (Pt 1 @CN) with Pt–N 4 coordination for stable and efficient CO 2 photoreduction using H 2 O as reductant. The Pt 1 @CN exhibits an evolution rate of 84.8 μmol g −1 h −1 with nearly 100% CO selectivity, outperforming most previous C 3 N 4 -based single-atom photocatalysts. Experimental and DFT calculation results reveal that the Pt–N 4 coordinated active sites promote the photogenerated electron transfer, CO 2 adsorption/activation, *COOH generation, and *CO desorption, thus accounting for the significantly improved CO 2 photoreduction activity with ∼100% CO selectivity. This study provides a deep insight into the significant roles of single-atom active sites in enhancing the CO 2 photoreduction activity and regulating the product selectivity.