Embedded Hard Base Sites in 1D Covalent Organic Frameworks Enable Selective Photocatalytic Uranium Recovery from Rare Earth Leaching Solution.

Lei, Huiying; Li, Yameng; Yang, Yile; Song, Fangru; Yu, Fengtao; Qiu, Jian-Ding · Nano Lett · 2026

basic_science · Level V

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Abstract

Selective uranium recovery from rare earth leaching solutions is hindered by competing ions and similar chemistry. Herein we propose a "framework-embedded hard base sites" strategy that simultaneously resolves selectivity and charge separation bottlenecks. By anchoring oxygen atoms as hard bases into 1D covalent organic frameworks (COFs), we create a dual-function platform where oxygen sites selectively capture uranyl ions while delocalizing excitons, lowering the exciton binding energy to 56.2 meV. The optimal COF-PODA with the highest density of oxygen sites achieves a high adsorption capacity of 1205 mg g<sup>-1</sup> and reduction kinetics of 0.079 min<sup>-1</sup>. In actual rare earth leaching solution, it removes 99.5% of uranium with outstanding selectivity over lanthanides and retains more than 95% activity after six cycles. This work uncovers an unforeseen synergy between hard-base coordination and electronic modulation, establishing a new design route for advanced radionuclide photocatalysts.