Photocatalytic uranium extraction based on covalent organic frameworks

Sustainable uranium extraction from seawater and nuclear wastewater is crucial for meeting global energy demands and ensuring environmental safety. Photocatalysis, as a highly promising strategy, can significantly enhance the kinetics, capacity, and selectivity of uranium extraction processes. Covalent organic frameworks (COFs), featuring crystalline porous architectures, tunable electronic structures, large surface areas, and exceptional stability, have emerged as highly potential photocatalysts for uranium recovery. This review first provides an overview of the background to uranium extraction, followed by a brief discussion of the photocatalytic reduction mechanism and various reaction pathways. We then summarize the recent advances in COF-based photocatalytic uranium extraction, focusing on design strategies and performance-optimization methods for pristine, functionalized, and composite COFs. Key strategies include donor-acceptor (D-A) structures, multicomponent modulation, functional group incorporation, defect engineering, and precise morphological control. These approaches effectively enhance light absorption, charge-carrier separation, and uranium-binding capacity. Additionally, COF membranes and gel materials exhibit practical advantages in processability, recyclability, and interfacial charge transport. Finally, this review discusses the challenges currently faced and future perspectives.