Hydrogen Radical Mediated Concerted Electron-Proton Transfer in 1D Sulfone-based Covalent Organic Framework for Boosting Photosynthesis of H

Solar-driven photocatalytic oxygen reduction reaction using covalent organic frameworks (COFs) offers a promising approach for sustainable hydrogen peroxide (H2O2) production. Despite their advantages, the reported COFs-based photocatalysts suffer insufficient photocatalytic H2O2 efficiency due to the mismatched electron-proton dynamics. Herein, we report three one-dimensional (1D) COF photocatalysts for efficient H2O2 production via the hydrogen radical (H•) mediated concerted electron-proton transfer (CEPT) process. The DOTh-COF which features dibenzo[b,d]thiophene sulfone (DOTh) moieties in the 1D skeleton edges achieves a high H2O2 production rate of 10.87 mmol g-1 h-1 and an apparent quantum efficiency of 13.5% at 420 nm in a biphasic water/benzyl alcohol system. The fs-TAS and in-situ EPR analyses demonstrate the DOTh moieties facilitate the charge separation, proton affinity, and exciton dissociation, enabling enhanced H• production. Mechanistic studies reveal that the H• reacts with O2 with high rate through both one-step and two-step 2e- pathways, thereby achieving efficient photosynthesis of H2O2. This work provides an effective design strategy for COFs-based photocatalysts and highlights the significance of H• mediated CEPT process in artificial photosynthesis.