Abstract: Photocatalytic production of H₂O₂ by polymeric carbon nitride has been regarded as a promising approach for the conversion of solar energy into valuable chemicals. However, the efficiency of pristine carbon nitride is limited by the rapid charge recombination and the lack of suitable active sites. Herein, we introduce single-atom Cu anchored on N-doped graphene (Cu-NG) as a cocatalyst coupled with carbon nitride via covalent bonding to enhance photocatalytic H₂O₂ production. The Cu-NG/carbon nitride could broaden the light absorption from UV to near-infrared region, contributing to the photocatalytic process. Moreover, NG containing electron-rich N atoms could serve as anchoring sites for stabilizing single-atom Cu. Importantly, the single-atom Cu acts not only as an electron sink to steer the interfacial charge separation but also as an active site for molecular oxygen adsorption and activation. With the synergistic effect of the enhanced interfacial charge separation and suitable active sites, Cu-NG/carbon nitride exhibits improved photocatalytic performance with an H₂O₂ generation rate of 2856 µmol g^-1 h^-1, which is 2.6 times that of pristine carbon nitride. This work provides a protocol for high-performance photocatalytic H₂O₂ production using a single-atom cocatalyst.

Key words: Single-atom catalysis, Interfacial charge separation, Photocatalytic H₂O₂ production