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We report the first example of covalent organic framework (DHBD-TMT) linked by unsubstituted olefin-linkages for selective loading, chemical reduction and photocatalytic reduction of uranium. The unique structures of DHBD-TMT possess all the characteristics to be well suited as a capture platform for selective ligand complexation, efficient chemical reduction and photocatalytic reduction of uranium, thus exhibiting a groundbreaking uranium capture capacity (2640.8 mg g-1). [Display omitted] • Covalent organic framework (DHBD-TMT) as a uranium adsorbent through three synergistic mechanisms. • This is the first example of covalent organic framework for selective adsorption, chemical reduction and photocatalytic reduction of uranium. • DHBD-TMT is very suitable as a capture platform for selective ligand complexation, efficient chemical reduction and photocatalytic reduction of uranium. • DHBD-TMT exhibited a groundbreaking uranium capture capacity. Herein, we report the first example of covalent organic framework (DHBD-TMT) linked by unsubstituted olefin-linkages for selective loading, chemical reduction and photocatalytic reduction of uranium. The unique structures of DHBD-TMT possess all the characteristics to be well suited as a capture platform for selective ligand complexation, efficient chemical reduction and photocatalytic reduction of uranium, thus exhibiting a groundbreaking uranium capture capacity (2640.8 mg g-1). In the dark, DHBD-TMT can effectively adsorb uranium through the hydroxyl groups laced on the skeleton and reduce UVI to UIV in situ, leading to a higher adsorption capacity and selectivity of uranium. At the same time, the synergistic effect of the hydroquinone and triazine units in the extended π-conjugated skeleton significantly improve the photocatalytic activity of DHBD-TMT, and an additional UVI photocatalytic reduction mechanism can occur under visible light irradiation, allowing significantly higher the capacity and faster adsorption kinetics. [ABSTRACT FROM AUTHOR]

The radioactive ion U(VI) and organophosphorus pollutants in sewage do great harm to the ecological environment and human health. Bifunctional photocatalyst MOF525@BDMTp was prepared by in-situ covalent bridging method, and U(VI) and chlorpyrifos (CP) were removed by one-to-two strategy. MOF525@BDMTp had high carrier migration performance and conformed to the type-II heterojunction. Under light conditions, electrons were transferred from MOF525 to BDMTp due to the action of the built-in electric field, increasing the electron density of BDMTp and thus activating the U(VI) binding sites. BDMTp interacted with S and N atoms in CP to promote its hydrolysis and oxidation by h+ and ·O 2 -. Thus, MOF525@BDMTp guaranteed the simultaneous reduction of U(VI) on BDMTp and the oxidation of CP on MOF525. Therefore, designing functional integrated composites is an effective means to improve the photocatalytic performance of composite materials in complex environments. [Display omitted] • MOF525@BDMTp was prepared by in-situ covalent bond bridging method. • MOF525@BDMTp can adsorb both U (VI) and chlorpyrifos. • Type-II heterojunction in MOF525@BDMTp improved electron-hole separation. • The presence of U(VI) and CP improved the removal performance of each other. [ABSTRACT FROM AUTHOR]