Regulating the Distance of Electron Transfer in Anthraquinone-Based Covalent Organic Framework for Efficient Photocatalytic U(VI) Reduction
Photocatalytic reduction of soluble U(VI) to insoluble U(IV) is a pivotal technology for uranium remediation and resource recovery. However, conventional covalent organic frameworks (COFs) suffer from short-range electron transport, leading to rapid electron-hole recombination and limited efficiency. Here, we report the rational design of anthraquinone-based COFs with donor-acceptor (D-A) architectures, employing 2,4,6-triformylphloroglucinol (TP) as the donor and 1,4-diaminoanthraquinone (1,4-DQ) or 1,5-diaminoanthraquinone (1,5-DQ) as the acceptor. By varying the connection mode of the building units, the electron transfer distance is systematically extended, effectively suppressing charge recombination. Among the synthesized COFs, ECUT-COF-152 exhibits optimal photocatalytic activity under visible light, achieving 100% U(VI) removal with a maximum reduction capacity of 1950 mg g−1. This work demonstrates that precise tuning of the D-A structure and electron transfer pathways is an effective strategy to enhance the photocatalytic performance of COFs for uranium reduction, offering insights for the design of efficient materials for nuclear waste treatment.