Interlayer Hydroxyl Self-Regeneration in Nickel–Aluminum Layered Double Hydroxides for Electrochemical Uranium Extraction from Nuclear Wastewater

Electrochemical extraction of uranium from nuclear wastewater offers the dual benefit of resource recovery and environmental remediation. However, in a high-fluoride real environment, the formation of extremely stable uranyl-fluoride complexes (UO₂F_<i>x</i>) severely impedes uranium recovery due to competitive coordination. Here, we propose an interlayer hydroxyl (-OH) enrichment strategy to confine UO₂F_<i>x</i> and facilitate its conversion to insoluble diuranates. A nickel-aluminum layered double hydroxide grown on nickel foam (Ni-Al LDH@NF) was designed, which achieves 93.8% uranium extraction within 100 min from a solution containing 30 g L^-1 F^- and 100 mg L^-1 U. Moreover, the electrode surpasses the site-saturation limit, achieving deep uranium extraction (99.3%) in nuclear wastewater with a uranium concentration of ∼1 g L^-1. A combination of theoretical and in situ spectroscopy demonstrated that UO₂F_<i>x</i> was captured by Ni sites and subsequently transformed into diuranate crystals via self-regenerated -OH groups enriched at interlayer Al sites. This work establishes a strategy for uranium recovery in complex wastewater matrices.