Ambient Preparation of Benzoxazine‐based Phenolic Resins Enables Long‐term Sustainable Photosynthesis of Hydrogen Peroxide

Abstract Rational design of polymer structures at the molecular level promotes the iteration of high‐performance photocatalyst for sustainable photocatalytic hydrogen peroxide (H 2 O 2 ) production from oxygen and water, which also lays the basis for revealing the reaction mechanism. Here we report a benzoxazine‐based m ‐aminophenol‐formaldehyde resin (APFac) polymerized at ambient conditions, exhibiting superior H 2 O 2 yield and long‐term stability to most polymeric photocatalysts. Benzoxazine structure was identified as the crucial photocatalytic active segment in APFac. Favorable adsorption of oxygen/intermediates on benzoxazine structure and commendable product selectivity accelerated the reaction kinetically in stepwise single‐electron oxygen reduction reaction. The proposed benzoxazine‐based phenolic resin provides the possibility of production in batches and industrial application, and sheds light on the de novo design and analysis of metal‐free polymeric photocatalysts.