Engineering electron acceptors in fluorinated covalent organic frameworks toward high-efficiency photocatalytic...

Covalent organic frameworks (COFs) are promising for metal-free, sustainable photocatalytic hydrogen peroxide (H₂O₂) production from water and oxygen. However, their current photocatalytic efficiency remains hampered by insufficient charge separation and migration, limiting practical applications. To tackle this issue, we developed three donor-acceptor (D-A) COFs with hcb topology by incorporating fluorine-containing groups into the acceptor units, thereby enhancing the electron-transfer capability within the D-A conjugated system. Photochemical characterization and theoretical calculations revealed a significant charge difference between the adjacent benzene rings of the donor and acceptor in the non-fluorinated D-A COF (TAPB-TPA COF), indicating that the D-A structure itself facilitates the migration of photogenerated electrons. In the fluorinated TFTA-TPA COF, the charge difference between adjacent benzene rings was further increased, which not only promoted efficient carrier migration but also optimized the oxygen reduction reaction (ORR) pathway. Notably, a production rate of 5785.2 μmol·g^-1·h^-1 for H₂O₂ was achieved by TFTA-TPA COF under sacrificial-agent-free conditions in pure water, significantly surpassing the performance of TAPB-TPA COF. Furthermore, TFTA-TPA COF was applied to tumor therapy, where its in-situ generated H₂O₂ induced cell death with good biocompatibility and therapeutic efficacy. This work offers a fresh perspective on the utility of COF materials, bridging photocatalysis and biomedicine.