Dual-Channel Electron Modulation via Cu-N2 Sites and π-Conjugated Framework in COF for Enhanced Photocatalytic Degradation of Fluorinated Pharmaceuticals.

The degradation of persistent fluorinated pharmaceuticals under mild conditions remains a formidable challenge in water treatment. Herein, a π-conjugated covalent organic framework (Cu@PCT-COF) featuring atomically dispersed Cu-N2 coordination sites is reported, which synergistically integrates visible-light harvesting and peroxydisulfate (PDS) activation for efficient photocatalytic degradation of 5-fluorouracil (5-FU). The integration of an extended π-conjugated backbone with atomically dispersed Cu-N2 sites forms a dual-channel electron transport pathway, which significantly enhances interfacial charge transfer and expedites reactive oxygen species (ROS) generation. Driven by this dual-channel electron transport pathway, Cu@PCT-COF achieves 100% removal of 5-FU within 15 min, which is 4.7 times higher than that of the PCT-COF/PDS/vis system and over 10 times greater than systems lacking either vis or PDS. Furthermore, the catalyst exhibits excellent stability, recyclability, and performance across varied pH and ionic conditions, and shows broad-spectrum activity toward diverse pollutants. EPR and quenching experiments identify •OH and SO4 •- as the primary ROS. Moreover, toxicity analysis and HPLC-MS/MS reveal a defluorination-initiated ring cleavage pathway, effectively reducing ecological risks. This work offers a promising strategy that leverages π-electron delocalization and single-atom engineering to realize efficient photocatalytic remediation of fluorinated contaminants.