Insight Into Fluorine–Nitrogen Synergistic Modification on Covalent Organic Frameworks for Efficient H 2 O 2 Synthesis by Visible Light Catalysis

Abstract This study presents an approach of fluorinated nitrogen‐heterocycles in covalent organic frameworks (COFs) to achieve highly efficient photocatalytic synthesis of hydrogen peroxide (H 2 O 2 ). Specifically, two trifluoropyridyl‐ and trifluorophenyl‐functionalized triamino monomers are designed and synthesized. Their polycondensations with triformylphloroglucinol under solvothermal conditions create two fluorinated COFs (TFPyCOF and TFBCOF). Compared to TFBCOF, the simultaneous incorporation of fluorine and nitrogen in the aromatic heterocycles of TFPyCOF enhances the photo‐excited electron–hole separation and charge transfer. Meanwhile, the fluorinated TFPyCOF exhibits greatly improved surface hydrophilicity. As a result, under visible light catalysis, its H 2 O 2 production rate (HPR) in water and oxygen atmosphere considerably rises from 4575 µmol g −1 h −1 of TFBCOF to 8845 µmol g −1 h −1 without any sacrificial agent. Even though replacing oxygen gas with air as feedstock, the HPR of TFPyCOF still reaches 6381 µmol g −1 h −1 , which can compete with the highest value for the photocatalysts reported to date unther the similar condition. The revealed structure‐property relationships and synergistic mechanism of fluorine–nitrogen modification offer new insights into the molecular engineering for COF‐based photocatalysts to boost high photocatalytic performance.