Harnessing Proton-Coupled Electron Transfer in Covalent Organic Frameworks for High-Yield H 2 O 2 Photosynthesis

Photocatalytic H 2 O 2 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 H 3 PO 4 treatment to introduce proton-conducting H 3 PO 4 molecules via hydrogen bonding. The resulting protonated P-TpDz exhibits significantly improved H 2 O 2 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 H 3 PO 4 molecules promotes rapid proton delivery to active sites, thus lowering the energy barrier for hydroperoxyl radical reduction to H 2 O 2 .