Facilitating Charge Spatial Separation for Efficient Photocatalytic H ₂ O ₂ Production via Ester‐Oxygen Bridged Organic Anthraquinone and Curved Open‐Ring g‐C ₃ N ₄ Structures

Abstract Photocatalytic two‐electron oxygen reduction for hydrogen peroxide (H ₂ O ₂ ) production represents a cost‐effective and sustainable synthetic approach. Inexpensive carbon nitride (g‐C ₃ N ₄ ) features a tunable bandgap and impressive photocatalytic performance in the 2e ⁻ ORR. This study presents the design of a defect vacancy ring‐opening g‐ ₃ N ₄ that introduces specific C─OH sites at the edges of the ring openings. The g‐ ₃ N ₄ is covalently bonded to anthraquinone (AQ) via ester C─O─C═O oxygen bridges, resulting in a CN─O─AQ catalyst characterized by a silk‐like, ordered stacked layer structure. The incorporation of specialized oxygen bridge bonds alters charge transport dynamics, establishing rapid charge diffusion pathways that enhance electron migration to the surface during the photoactivated oxygen reduction reaction. The synergistic effects of optimizing the (100) crystal plane crystallinity and introducing dual O/Cl element doping promote the development of new light absorption centers and lower oxygen adsorption energy while creating suitable electron vacancies. The CN─O─AQ catalyst achieved an impressive H ₂ O ₂ yield of 626 mmol L ⁻¹ , which is 14.9 times higher than that of pure CN (42 mmol L ⁻¹ ). This work elucidates the dual impact of modulating both crystal and electronic structures on photocatalytic performance, offering valuable insights for designing defect sites and doping strategies in organic conjugated structure catalysts.