Efficient ytterbium-doped Bi2WO6 photocatalysts: Synthesis, the formation of oxygen vacancies and boosted superoxide yield for enhanced visible-light photocatalytic activity

Yb-doped Bi2WO6 nanomaterials were successfully synthesized using a mild hydrothermal method. Remarkably, Yb-doped Bi2WO6 photocatalysts exhibited a higher photocatalytic activity than pristine Bi2WO6 by degrading RhB under visible light irradiation. The optimum mass ratio of Yb to Bi2WO6 was 2.0%, and it presented the highest photo-degradation efficiency. The crystal structures, morphologies, surface chemical states, and optical properties of the as-synthesized photocatalysts were carried out by XRD, SEM, XPS and DRS, respectively. The results of electron paramagnetic resonance spectroscopy, radical trapping experiments, photoluminescence spectroscopy and photocurrent measurements indicated that the Yb-doped Bi2WO6 samples produced more oxygen vacancies and superoxide anion active groups (.O2−), inhibited the recombination of the photo-generated electron-hole pairs, and enhanced the photo-degradation performance. As a result, the dopant Yb3+ could enhance photocatalytic performance of Bi2WO6 by introducing oxygen vacancies into its lattice. This study provides a useful strategy for developing effective visible light photocatalysts.