Interfacial design of pyrene-based covalent organic framework for overall photocatalytic H₂O₂ synthesis in water

Covalent organic frameworks (COFs) have shown great potential in the photocatalytic production of hydrogen peroxide (H₂O₂) due to their precisely designed and customized ability. Nevertheless, the quest for efficient overall photosynthesis of H₂O₂ in pure water without sacrificial agents using COF photocatalysts remains a formidable challenge. Herein, three pyrene-based covalent organic frameworks are synthesized using an advanced interfacial design strategy. By incorporating functional groups of F, H, and OH into a COF skeleton, their wettability and charge-separation properties are fine-tuned. These COFs show great performances as photocatalysts for H₂O₂ production from water and air by utilizing both the oxygen reduction reaction and water oxidation reaction pathways. Compared to PyCOF-F and PyCOF-H, PyCOF-OH demonstrates superior H₂O₂ production efficiency due to its improved hydrophilicity and enhanced carrier separation, achieving a remarkable rate of 2961 µmol g^-1 h^-1 from 25 mL pure water and air. Further, the mechanism of H₂O₂ production over PyCOF-OH is clarified by combining a series of control experiments, in situ characterizations, and theoretical calculations. This study offers valuable insights into the interfacial design of high-performance photocatalysts for H₂O₂ synthesis.