Phosphate-bridged monolithic photocatalytic panels for continuous-flow H2O2 photosynthesis

Phosphate-mediated interfacial Al–O–P–N bonding enables robust anchoring of P-doped carbon nitride film onto alumina panels. • Spatially separated CN=O and CN–P sites drive dual-channel 2e – WOR and ORR pathways for selective H 2 O 2 photosynthesis. • A flow reactor with 9 photocatalytic panels produces H 2 O 2 at a rate of 2066.68 μmol h –1 m –2 under simulated sunlight. • The flow reactor retains 97.0% H 2 O 2 production activity after ten consecutive cycles. • The flow reactor shows great potential for environmental remediation by achieving 98.52% MB degradation within 30 min. The practical deployment of photocatalytic H 2 O 2 synthesis is severely hindered by the reliance on suspended powder catalysts, which suffer from aggregation, catalyst loss, and limited compatibility with continuous-flow reactor systems. Herein, we report a phosphate-bridged monolithic photocatalytic platform in which P-doped carbon nitride is directly integrated with α-Al 2 O 3 substrates through covalent Al–O–P–N interfacial linkages. During growth, phosphate simultaneously mediates catalyst-substrate coupling, phosphorus incorporation, and defect engineering, thereby enabling robust catalyst immobilization together with optimized charge transport and interfacial reaction kinetics. The resulting monolithic photocatalytic panels exhibit exceptional mechanical stability and near-lossless recyclability, minimizing catalyst detachment and recovery losses during continuous-flow operation. Experimental characterizations and density functional theory calculations reveal spatially separated catalytic centers, where defect-derived CN O sites preferentially drive the two-electron water oxidation reaction while phosphorus-substituted CN-P sites promote the 2e − oxygen reduction reaction, collectively enabling dual-channel H 2 O 2 photosynthesis. Under simulated sunlight, a continuous-flow reactor assembled with 9 monolithic panels achieves a H 2 O 2 production rate of 2066.68 μmol h −1  m −2 , while maintaining nearly unchanged activity after ten operational cycles. As a proof-of-practicality demonstration, the same monolithic reactor also enables rapid MB degradation under continuous-flow conditions. This work establishes a scalable photocatalytic platform that bridges the gap between laboratory-scale powder photocatalysts and practically deployable solar-driven H 2 O 2 production systems.