Engineering Charge Transfer Channels in D-π-A Structured Multicomponent COFs for Efficient Photocatalytic Uranium Extraction Coupled with Organic Degradation

Abstract

Photocatalysis provides a promising way to simultaneously extract uranium and degrade organics in uranium-bearing waters through the in situ-generated reactive oxygen species (ROS). However, conventional donor–acceptor covalent organic frameworks (D–A COFs) are hampered by inefficient charge separation and sluggish interfacial transfer. Here, a multi-component COF (MC-COF) was designed and prepared with donor-π-acceptor (D-π-A) structure and cyano bearing π-bridge (named MC-COF-Db), which could effectively modulate the visible light harvesting and inhibit charge recombination. Impressively, MC-COF-Db achieved a uranium extraction efficiency over 90%, while concurrently degrading tetracycline, ciprofloxacin, bisphenol A and sulfamethoxazole with efficiency exceeding 96 %. Experimental and theoretical data reveal that the cyano site provides an additional charge transfer pathway, promoting the exciton dissociation/transfer and boosting the generation of ·O2- and H2O2. The in situ-generated ROS could simultaneously transform dissolved uranyl ions to metastudtite solids and degrade organic pollutants. This work underscores the pivotal role of π-bridge design in unlocking the full photocatalytic potential of COFs for coupled uranium recovery and water remediation.