Recent Advances of COFs-based Materials for Photocatalytic U(VI) Separation: Structural Modulation and Mechanistic Exploration.

The development of efficient and selective U(VI) extraction from seawater and U(VI)-containing wastewater through photocatalytic technology holds significant importance for nuclear energy advancement and mitigation of radionuclide-related environmental and health risks. Covalent organic frameworks (COFs) have emerged as ideal photocatalytic materials for U(VI) separation due to their inherent porosity, robust frameworks, chemical stability, and exceptional structural regularity. This comprehensive review examines molecular-level structural optimization of COFs to enhance charge carrier separation and transfer, thereby improving photocatalytic U(VI) extraction efficiency. We systematically evaluate multiple design strategies, including: Donor-Acceptor (D-A) structure regulation, covalent linkage engineering, COF-based heterojunction construction, Metal-covalent organic frameworks (MCOFs) development, and piezo-photocatalytic synergy. Furthermore, we have discussed the fundamental principles of U(VI) separation mediated by COFs and carefully analyzed the mechanisms of U(VI) separation through photocatalysis by COFs. Finally, we analyzed the challenges faced in the photocatalytic separation of U(VI) based on COFs and prospected their development prospects. This review systematically summarizes the latest progress in the field of photocatalytic separation of U(VI) based on COFs, as well as the deficiencies in the catalytic mechanism. It can provide useful references for the rational design of efficient COF-based photocatalysts and in-depth exploration of the U(VI) separation mechanisms.