Predoped Isolated Uranyl in Molybdenum Oxide Enables Electrochemical Extraction of Uranium from Fluoride-Containing Nuclear Wastewater

Electrochemical uranium extraction represents a powerful means to achieve the recovery of uranium resources from nuclear wastewater, but the formation of a complex between fluoride and uranyl in common wastewater severely decreases the extraction efficiency. Herein, the isolated uranyl was predoped in O-vacancy-containing molybdenum oxide (U-MoO_3-<i>x</i>, <i>x</i> < 3) to efficiently electrochemical extract uranium from fluoride-containing nuclear wastewater. In this system, the doped isolated uranyl and the vacancy of the O can strongly bind with the fluorine and uranyl in uranyl fluoride (UO₂F_<i>x</i>), respectively, enabling the synergistic trapping of dominant species in fluoride-containing nuclear wastewater. With the coexistence of high concentration of fluoride (3 g/L), the U-MoO_3-<i>x</i> nanosheets exhibited a removal efficiency of 95.3% for uranium, which was much higher than that of MoO_3-<i>x</i>. Furthermore, the U-MoO_3-<i>x</i> nanosheets displayed robust uranium extraction performance with a negligible influence of pH variations, interfering ions, and U/F ratios. This work provides a new strategy of preintroduction of uranyl species for promoted electrochemical uranium extraction in a complex environment.