Facilitated electron-hole separation and enhanced uranium(VI) capture via La-doped WO3: Insights into oxygen vacancies and superior recyclability

WO 3 -based materials are theoretically promising photocatalysts for uranium(VI) removal due to their stability and narrow bandgap (∼2.8 eV), but they are limited by a lack of adsorption sites and a tendency for photogenerated electron-hole pairs to recombine. Herein, La-doped WO 3 (W 0.9 La 0.1 O 3-x ) rich in oxygen vacancies (OVs) was prepared via a facile hydrothermal method. La doping and the introduction of OVs provided abundant active sites, optimized the band structure, increased electron density, and inhibited electron-hole pair recombination of W 0.9 La 0.1 O 3-x , which resulted in a maximum U(VI) extraction capacity of up to 1199.73 mg/g through synergistic adsorption-photocatalytic reduction processes. Interestingly, W 0.9 La 0.1 O 3-x demonstrated excellent stability and increased recyclability, superior to that of most reported adsorbents and photocatalysts, probably owing to the strong stability of W and La atoms as well as the additional OVs formed from self-reduction of W 0.9 La 0.1 O 3-x during photocatalytic reaction process. Overall, this study expands the application of WO 3 -based materials for U(VI) removal from wastewater and provides valuable theoretical insights and technical guidance for addressing the challenge of balancing removal rate and stability of U(VI) extraction materials.