Synthesis of quinone-amine-linked covalent organic frameworks for boosting the photocatalytic removal of uranium

Compared to imine covalent organic frameworks (COFs), the superior stability of amine-linked COFs renders them more suitable for long-term harsh real-world environments. Their numerous amine sites can serve as functional groups or be subjected to post-modification to further enhance the performance of the material. However, the assortment and abundance of amine-linked COFs via currently lacking due to restricted monomer varieties and synthetic methods. Herein, this study presents an innovative approach for synthesizing quinone-amine-linked COFs by directly combining 2,5-dihydroxy-1,4-benzoquinone (DHBQ) with various amine monomers and introduce a novel photocatalyst, DHBQ-TAPP-COF, specifically tailored to efficiently reduce uranium in harsh environments. DHBQ-TAPP-COF features a unique donor-acceptor structure, with the DHBQ units serving as acceptors because they contain abundant oxygen atoms that facilitate metal ion coordination, thereby enhancing charge carrier separation, carrier utilization, and uranium reduction efficiency. The quinone-amine linkages offer improved stability, extended π-conjugation, heightened local polarity, and conductivity, which enable efficient carrier transfer within the material and thus enhance the overall performance of the uranium photocatalyst. The proposed photocatalyst can efficiently reduce U(VI) without sacrificial agents or decomposition to precipitate UO${}_2$ at a recovery rate exceeding 98%. This catalyst provides an efficient and convenient strategy for the stable and high-performance photocatalytic reduction of uranium. (© 2024 Wiley‐VCH GmbH)