Hydrogen-incorporated vanadium dioxide nanosheets enable efficient uranium confinement and photoreduction

Photocatalytic reduction of U(VI) represents a novel and effective manner for the removal of U(VI) pollutant from radioactive wastewater. Herein, we successfully incorporated hydrogen into VO2 nanosheets, which strengthened the interaction between VO2 and U(VI), thereby achieving a highly active and stable photocatalyst for U(VI) reduction. With the increase of H content in hydric VO2 (HX-VO2) nanosheets, the bandgap shrank from 2.29 to 1.66 eV, whereas the position of conduction bands remained more negative than the reduction potential of U(VI)/U(IV) (0.41 V vs. NHE). When irradiated by simulated sunlight, the U(VI) removal efficiency over H0.613-VO2 nanosheets reached up to 95.4% within 90 min, which largely outperformed 28.3% of pristine VO2 nanosheets. The mechanistic study demonstrated that the hydroxylated surface gave rise to the balanced O confinement sites in VO2 (011), leading to the stabilized adsorption configuration and increased binding strength of UO22+ on HX−-VO2 nanosheets.