Trace Cu^II modification of covalent organic frameworks for photocatalytic hydrogen peroxide generation via...

Hydrogen peroxide (H₂O₂) is widely used as a green strong oxidant. The photocatalytic H₂O₂ production over covalent organic frameworks (COFs) is of great promise for energy conversion and pollution remediation. In this study, a copper-modified COF (TD-Cu) was constructed, showing effective photocatalytic H₂O₂ production. The H₂O₂ production rate of TD-Cu was 1.41 times that of the pristine TD COF under ambient air conditions in pure water as well as other natural water resources, and it even reached a record-high H₂O₂ yield of 9552 μmol·h^-1·g^-1 under oxygen-enriched conditions in pure water, outperforming most reported catalysts. Experimental results reveal that the introduction of Cu²⁺ into TD COF accelerates the separation of photoinduced e^--h⁺ pairs and facilitates the active sites favorable for O₂ adsorption and ·OOH intermediate formation, thereby promoting the selective two-electron oxygen reduction pathway as well as efficient H₂O₂ evolution. This study not only highlights a novel trace-metal modification strategy that effectively regulates charge transfer and active-site dynamics in COFs, but also underscores its broader implications for developing efficient, sustainable, and scalable artificial photosynthesis systems for green chemical synthesis and environmental purification.