Harnessing Proton-Coupled Electron Transfer in Covalent Organic Frameworks for High-Yield H₂O₂ Photosynthesis

Photocatalytic H2O2 production via the 2e– ORR is a promising green technology but suffers from competition with the 4e– ORR and inherent limitations in traditional photocatalysts. To address these limitations, we developed a strategy leveraging the PCET process by synthesizing pyridazine-functionalized, nitrogen-doped COFs to enhance electrophilicity followed by H3PO4 treatment to introduce proton-conducting H3PO4 molecules via hydrogen bonding. The resulting protonated P-TpDz exhibits significantly improved H2O2 photocatalytic activity and selectivity over the two-electron pathway compared with the pristine COF, attributed to enhanced charge separation and facilitated proton transport. Mechanistic studies suggest that the H3PO4 molecules promotes rapid proton delivery to active sites, thus lowering the energy barrier for hydroperoxyl radical reduction to H2O2.