Facile Construction of Vinyl-Linked Zwitterionic Covalent Organic Frameworks for Efficient Uranium Capture

Extracting uranium from seawater is essential for sustainable nuclear energy but remains a great challenge. Herein, an ionized monomer, PSTMP, which can specifically interact with uranium by strong electrostatic interaction, was incorporated to construct a vinyl-linked zwitterionic covalent organic framework, TFPT-COF-SO 3 –, via a bottom-up strategy. The vinyl linkage endows TFPT-COF-SO 3 – with robust structural stability and chemical resistance, while the pendant SO 3 – groups enable strong electrostatic interaction with UO 2 2+ . Benefiting from the high density and uniform distribution of the ionic sites throughout the frameworks, the resulting TFPT-COF-SO 3 – exhibits a high adsorption capacity (962 mg·g –1 ) and rapid kinetics (achieving 97% removal from a 10 ppm solution within 35 min) for UO 2 2+ capture. Moreover, it maintains good performance under seawater-relevant conditions, with the UO 2 2+ adsorption capacity of 17.23 mg g –1 in simulated seawater. Mechanism investigations reveal a synergistic electrostatic-coordination and in situ reduction mechanism; the negatively charged –SO 3 – on TFPT-COF-SO 3 – offers a strong electrostatic driving force for rapid UO 2 2+ capture, followed by the stable coordination and partial in situ reduction of U (VI) to U (IV). This work demonstrates that the bottom-up strategy for constructing zwitterionic COFs with high charge density represents an effective approach for efficient uranium capture.