Cyano-Functionalized\nPolyarylether-Based Covalent\nOrganic Framework for Highly Efficient Photocatalytic Uranium Extraction

Uranium is the primary fuel for nuclear power. Extracting\nuranium\nfrom uranium-containing water bodies is of great strategic importance\nto solve the problems in the advance of nuclear energy. Photocatalytic\nuranium separation technology has the advantages of high uranium extraction\nefficiency and easy separation of products. It is of great significance\nto develop photocatalytic materials that can extract uranium effectively\nunder visible light without sacrificial agents. In this work, polyarylether\ncovalent organic frameworks containing different amounts of cyano\ngroups were prepared, and the photocatalytic performance and mechanism\nof uranium extraction were studied. PAE-COF-DC exhibited superior\nuranium extraction efficiency under air and visible light conditions,\nand the uranium extraction efficiency in uranium-spiked seawater and\ngroundwater was 80% and 93%, respectively. PAE-COF-DC also showed\nexcellent reusable performance and anti-ion interference ability.\nThe mechanism study demonstrated that, driven by visible light, PAE-COF-DC\nused superoxide radicals as important intermediates to efficiently\ngenerate hydrogen peroxide in situ through oxygen reduction reaction,\nwhich promoted the solidification of uranium in the form of metastudtite.\nThis work provides insights into the design of highly efficient photocatalytic\nuranium extraction materials.