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 (UO2Fx) severely impedes uranium recovery due to competitive coordination. Here, we propose an interlayer hydroxyl (-OH) enrichment strategy to confine UO2Fx 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 UO2Fx 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.