Amidoxime-Functionalized sp²-Carbon-Conjugated Covalent Organic Frameworks for Overall Photocatalytic Hydrogen...

Cyano-functionalized sp²-carbon-conjugated covalent organic frameworks (CN-COFs) have been considered as promising candidates for artificial photosynthesis of hydrogen peroxide (H₂O₂). Nevertheless, the performance of CN-COFs is inherently limited by constrained oxygen capture capacity, insufficient charge separation, and rapid carrier recombination. Herein, the study rationally reports a strategy for integrating amidoxime groups (AO) into a COF through one-step cyano hydrolysis process to increase photocatalytic H₂O₂ production. Combined simulations and characterizations reveal that introducing AO groups enhances hydrophilicity, stabilizes adsorbed Oxygen (O₂) via hydrogen bonding, accelerates the charge separation and transfer, as well as lowers the energy barrier for oxygen reduction reaction pathway, thus achieving an unmatched H₂O₂ production rate of 6024 µmol h^-1 g^-1. Importantly, the solar-to-chemical conversion (SCC) efficiency of PTTN-AO reaches 0.61%, significantly surpassing that of natural plants (≈0.1%) and most COF-based photocatalysts. The current findings are encouraging for the molecular design of polymers for green and efficient H₂O₂ production.