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

Graphitic carbon nitride (g-C3N4) is a promising semiconductor for solar-to-chemical conversion, yet its practical application in hydrogen peroxide (H2O2) 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-C3N4/CuO (CuO/O─C3N4) heterostructures designed for highly efficient photocatalytic H2O2 production. By integrating atomic-level oxygen doping with interface-level CuO coupling, this strategy simultaneously regulates the intrinsic electronic structure of g-C3N4 and establishes an efficient interfacial charge-transfer pathway. The optimized CuO/O─C3N4-2 composite achieves a high H2O2 concentration of 3978 μmol L-1 under visible-light irradiation in an acidic medium with HCOOH as a sacrificial agent, significantly outperforming pristine g-C3N4. 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-C3N4-based systems toward sustainable solar-fuel production.