Oxygen vacancy regulation in Nb-doped Bi₂WO₆ for enhanced visible light photocatalytic activity

Novel Nb-doped Bi₂WO₆ nanosheets have been successfully synthesized by a simple hydrothermal method. XRD, Raman spectra, XPS and SEM were adopted to analyze the structure and morphology of the samples, then the structure-dependent optical properties, photoelectric behavior and photocatalytic activities were investigated, and the structure-property relationship was also discussed. The results show that doping Nb⁵⁺ can increase the oxygen vacancies in the Bi₂WO₆ lattice and reduce the optical band gap of Bi₂WO₆. The oxygen vacancies also act as electron traps, which promote the separation of photogenerated carriers. Hence, compared with the pure Bi₂WO₆, the as-prepared Nb-doped Bi₂WO₆ nanosheets exhibit enhanced visible-light photocatalytic activity for removing contaminants in water such as rhodamine B and tetracycline.