Bidirectional reactant flux coupling in hollow hierarchical covalent organic framework enabling efficient uranium extraction from seawater.
basic_science · Level V
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- Record sourced from PubMed, PMID 42321234.
- Also identified by DOI 10.1038/s41467-026-74724-3.
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Abstract
Photocatalytic uranium extraction can surpass the intrinsic capacity limits of adsorption by converting soluble uranyl into insoluble uranium peroxides via H<sub>2</sub>O<sub>2</sub> generation. However, this process requires simultaneous local enrichment of H<sub>2</sub>O<sub>2</sub> and UO<sub>2</sub><sup>2+</sup> beyond the solubility product constant, which is difficult to achieve in continuously flowing and ultra-dilute seawater. Here we report a hollow hierarchical covalent organic framework (COF) microcavity reactor, HH-COF-(CN/AO)<sub>x</sub>, that spatially decouples H<sub>2</sub>O<sub>2</sub> generation from uranyl capture to overcome this thermodynamic barrier via a bidirectional reactant flux coupling strategy. A cyano-functionalized inner layer produces and stores H<sub>2</sub>O<sub>2</sub> in a central cavity, whereas an amidoxime-rich outer layer selectively enriches uranyl ions. The convergence of outward H<sub>2</sub>O<sub>2</sub> flux and inward uranyl adsorption establishes a persistent high-concentration interface that supports continuous formation of insoluble uranium peroxide. The optimized HH-COF-(CN/AO)<sub>0.35</sub> achieves 25.1 mg g<sup>-1</sup> uranium uptake in natural seawater, 3.9 times that of the non-hollow analog, which demonstrates a generalizable strategy for manipulating reactant fluxes in ultra-dilute environments for realizing effective resource extraction from water environment.