Phytic acid-induced coordination defects regulate local electron separation in bimetallic metal-organic frameworks for boosting photocatalytic uranium reduction

Uranium serves as the core fuel for nuclear energy, and efficient uranium extraction from seawater is of great strategic significance for alleviating the shortage of terrestrial uranium resources. However, traditional metal-organic framework photocatalysts generally suffer from severe carrier recombination, weak visible-light response, and scarce active sites, which severely restrict their uranium removal performance in complex seawater systems. Herein, phytic acid was used to controllably etch bimetallic MOF (NH 2 -MIL-68(In/Fe)) to construct phytic acid-functionalized bimetallic MOF (NH 2 -MIL-68(In/Fe)-PA) with a hollow structure. The obtained hollow NH 2 -MIL-68(In/Fe)-PA possesses abundant phosphate groups on its surface and within its pores, providing numerous active sites for uranium adsorption. Meanwhile, phytic acid etching generates coordination defects, which facilitate local electron separation within NH 2 -MIL-68(In/Fe) and thus boost the performance of photocatalytic uranium reduction. The U(VI) reduction rate constant reaches 3.68 × 10 −4 g/(mg·min), 1.3 times that of the NH 2 -MIL-68(In/Fe), and the uranium removal efficiency reaches 91.1% within 120 min. The catalyst exhibits consistently high removal efficiency, strong anti-interference ability, and excellent selectivity. This work proposes a universal green modification strategy mediated by phytic acid, providing a new route for efficient photocatalytic uranium extraction.