Tuning oxygen vacancy in Bi₂WO₆ by heteroatom doping for enhanced photooxidation-reduction properties

Heteroatom doping was recently regarded as an effective method to tune the band gap and improve the separation and transfer of photogenerated electron-hole pairs in semiconductor photocatalysts. Herein, a novel S,F-codoped Bi₂WO₆ (S,F-Bi₂WO₆) with suitable oxygen vacancies was synthesized via the hydrothermal-calcination and post-sulfurization, for efficient Cr(VI) reduction and methyl orange (MO) degradation under visible light. The amount of surface oxygen vacancies could be controlled by adjusting the S/F ratio during the doping process, which modulated the band structure and photogenerated charge behavior of Bi₂WO₆. The optimal S_0.10F-Bi₂WO₆ exhibited an excellent photooxidation-reduction performance, which Cr(VI) reduction and MO degradation efficiencies were 1.6 and 2.6 times than those of the pristine Bi₂WO₆ without oxygen vacancy under visible-light, respectively. The enhanced photooxidation-reduction performance was because the right amount of oxygen vacancies could effectively narrow the bandgap and improve the separation efficiency of electron-hole pairs. Thus, this work offered a mild and simply approach for preparing heteroatom doped Bi₂WO₆ and a potential to be extended to the synthesis of other doped materials for environmental remediation.