Terminal p‐π Conjugation Embedded in Graphitic Carbon Nitride for Efficient H 2 O 2 Photosynthesis in Air

ABSTRACT The widespread deployment of photocatalytic technology still remains limited by its dependence on high‐purity gas inputs and specialized light sources. Achieving high efficiency under these conditions calls for rational structural design of photocatalysts. Here, we report a one‑precursor synthesis of graphitic carbon nitride (g‑C 3 N 4 ) featuring edge‑localized p‑π conjugation, using cyanuric acid alone, for efficient photocatalytic H 2 O 2 production in air. The degree of p‑π conjugation is regulated via hydroxyl group content, which is controlled by special calcination conditions. This conjugation promotes charge transfer by extending electron delocalization and prolonging exciton lifetime, while also strengthening O 2 adsorption to facilitate mass exchange. As a result, the synergistically optimized p‑π conjugated g‑C 3 N 4 prepared at 450°C achieves an H 2 O 2 photosynthesis rate of 3588 µmol g −1 h −1 under laboratory air and visible light, representing a 7.2‑fold enhancement over pristine g‑C 3 N 4 . Under natural sunlight outdoors, the rate further rises to 8845 µmol g −1 h −1 . This work provides a feasible structural engineering strategy to advance the practical application of photocatalytic H 2 O 2 generation.