Hydrogen Radical Mediated Concerted Electron-Proton Transfer in 1D Sulfone-based Covalent Organic Framework for...

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.