Record High Uranium Photoassisted Capture Performance from Fluorine-Containing Wastewater by Ag/WO_3–<i>x</i> with Surface Defect and Heterostructure

The uranium recovery from high concentration fluorine-containing uranium wastewater is a desired research target in the field of environmental radiochemistry but is very challenging due to the formation of stable uranium fluoride complexes that are quite difficult to extract. By employing surface defect engineering and interfacial heterostructure design, we present here the rational design of an efficient photocatalyst (Ag/WO_3-<i>x</i>) for U(VI) uptake from fluorine-containing uranium wastewater without any sacrificial agents. The defect-rich surface of Ag/WO_3-<i>x</i> facilitates confined adsorption of uranium, while the introduction of Ag nanoparticles enables both efficient electron-hole separation and a plasmon effect upon light irradiation. Ag/WO_3-<i>x</i> shows high U(VI) removal efficiency of 96.3% at 8 mg/L U(VI) within 60 min. Notably, even when the ratio of F^- to U(VI) is as high as 20:1, the removal efficiency of U(VI) by Ag/WO_3-<i>x</i> reaches up to 95%. Additionally, the maximum capture capacity of U(VI) on Ag/WO_3-<i>x</i> reaches 676.8 mg/g at 200 mg/L of U(VI) within 60 min, which is superior to ever-reported photocatalysts in fluorine-containing uranium wastewater. This work provides an effective way for the uranium capture from fluorine-containing wastewater through the synergy of plasmon effect and defect engineering.