Defect controlled MOF-808 for seawater uranium capture with high capacity and selectivity.

• MOF-808 with abundant missing linker defects was prepared. • Defective MOF-808 showed high uranium extraction capacity from natural seawater. • Defective MOF-808 had superior uranium adsorption selectivity over vanadium. • The high affinity of defective MOF-808 towards uranium comes from the increasing accessible Zr-O terminals. Highly effective extraction of uranium from seawater calls for the development of adsorbents with both high capacity and selectivity. Defective Zr-based metal–organic frameworks (MOFs) are potential candidates for uranium sequestration due to their high surface area and tunable active sites. In this work, MOF-808 samples with adjustable missing linker defects were successfully prepared by manipulating the concentration of the carboxylic acid modulator. Impressively, MOF-808 with the highest defect density, namely M808-4, showed excellent selectivity towards uranium in comparison with coexisting competitive ions in seawater. Moreover, M808-4 exhibited remarkable uranium extraction performance in real seawater with an uptake capacity of 5.83 mg/g in 28 d, which is 10.41 times higher than that for vanadium. The results indicated that the abundant Zr unsaturated active sites formed by defect inducing strategy are the key to the efficient capture of uranyl ions. This study highlighted the advantages of defect engineering in MOF based materials for highly selective uranium extraction from seawater. [ABSTRACT FROM AUTHOR]