Functionalized benzoxazine-based phenolic resins for in situ photosynthesis and utilization of hydrogen peroxide

The development of facile and scalable methods to fabricate green photocatalysts with efficient charge separation remain pivotal for advancing photocatalytic H₂O₂ production toward practical applications. Herein, a sulfonic acid-functionalized benzoxazine-based phenolic resin (SAPFac) was reported for in situ H₂O₂ production and utilization. The electron-withdrawing sulfonic groups (-SO₃H) induce a robust intramolecular built-in electric field and impart surface negative charges, thereby synergistically enhancing photogenerated carrier separation efficiency and optimizing proton/oxygen affinity. The sulfonic acid-linked benzene rings in SAPFac serve as electron-enrichment centers, lowering the energy barrier for *OOH intermediate formation to favor the 2e^- oxygen reduction reaction (ORR) pathway to generate H₂O₂. Consequently, this molecular engineering strategy endows SAPFac resins with an exceptional H₂O₂ production rate of 4410.9 μmol g^-1 h^-1 under visible light without sacrificial agents or oxygen aeration, which is 2.1 times of pristine benzoxazine-based phenolic resin (APFac). Coupled with Fe³⁺, photo-self-Fenton system was constructed to achieve rapid degradation of antibiotics and complete inactivation of high-density antibiotic-resistant bacteria (∼10⁷ CFU/mL) via in situ activation of H₂O₂ into hydroxyl radicals (•OH). This work establishes a green and sustainable paradigm for polymer photocatalyst design, promoting the development of real field implementation of solar-driven H₂O₂ synthesis technology.