Boosting Photocatalytic Hydrogen Peroxide Production via Multiscale Engineering O-Doped g-C3N4/CuO Nanosheets

Graphitic carbon nitride (g-C 3 N 4 ) is a promising semiconductor for solar-to-chemical conversion, yet its practical application in hydrogen peroxide (H 2 O 2 ) photosynthesis is severely limited by inefficient charge separation and rapid electron–hole recombination. Herein, we report a synergistic multiscale engineering strategy to construct O-doped g-C 3 N 4 /CuO (CuO/O─C 3 N 4 ) heterostructures designed for highly efficient photocatalytic H 2 O 2 production. By integrating atomic-level oxygen doping with interface-level CuO coupling, this strategy simultaneously regulates the intrinsic electronic structure of g-C 3 N 4 and establishes an efficient interfacial charge-transfer pathway. The optimized CuO/O─C 3 N 4 -2 composite achieves a high H 2 O 2 concentration of 3978 μmol L −1 under visible-light irradiation in an acidic medium with HCOOH as a sacrificial agent, significantly outperforming pristine g-C 3 N 4 . Comprehensive characterizations and theoretical insights reveal that the dual-functionalization of oxygen-induced electronic modulation and CuO-mediated interfacial charge transfer synergistically promote carrier separation and facilitate the two-electron oxygen reduction reaction. This work provides a sophisticated paradigm for the rational design of g-C 3 N 4 -based systems toward sustainable solar-fuel production. Graphical A facile synergistic multiscale engineering strategy is presented for the preparation of O-doped g-C 3 N 4 /CuO heterostructures with abundant nitrogen vacancies. The optimal CuO/O─C 3 N 4 -2 shows enhanced visible-light harvesting and charge separation, achieving superior photocatalytic activity for hydrogen peroxide production under visible-light irradiation.