Electron/Proton Transport Engineering in Acylhydrazone‐Linked Covalent Organic Framework for Efficient Solar‐driven H 2 O 2 Production

Abstract Hydrogen peroxide (H 2 O 2 ) is a vital industrial chemical extensively utilized in textiles, pharmaceuticals, and disinfection. Solar‐driven photocatalytic technology depending on photocatalysts with matched energy band structure for simultaneously driving both O 2 reduction and water oxidation half‐reactions, without necessary use of any sacrificial agent, enables green H 2 O 2 synthesis from O 2 and/or H 2 O, offering a low‐energy and simple‐operation process without secondary pollution while avoiding safety and environmental risk of conventional methods. Herein, a novel acylhydrazone‐linked 2D COF, COF‐S‐OH , was prepared from benzo[1,2‐ b :3,4‐ b ':5,6‐ b '']trithiophene‐2,5,8‐tricarbaldehyde and 2,3‐dihydroxysuccinohydrazide. Both experimental and theoretical analyses reveal that introduction of benzotrithiophene units and hydroxyl groups enhances the electron donor‐acceptor effect in COF‐S‐OH , optimizes the light‐harvesting and adsorption capacities to O 2 and H 2 O, and particularly enables efficient proton transfer, thereby synergistically improving photogenerated charge carrier separation and surface reaction efficiency. Consequently, COF‐S‐OH achieves an exceptional H 2 O 2 production rate of 10.2 mmol g −1 h −1 with a solar‐to‐chemical conversion efficiency of 2.1%, superior to all the thus far reported photocatalysts for H 2 O 2 synthesis. This work underscores the critical importance of carrier separation, active site, and proton supply in photocatalytic H 2 O 2 generation, providing guidance for designing and fabricating next‐generation photocatalysts.