Engineering oxygen vacancies in Bi2WO6 by introducing heteroatoms for enhancing photo-oxidation/reduction activities

To improve the light-harvesting capability and electron-hole separation efficiency, a novel heteroatom-introduced Bi2WO6 photocatalyst (OV-Bi2WO6) with oxygen vacancies (OVs) was prepared via the partial substitution of O2-by S2-anions. The OV-Bi2WO6 showed high photocatalytic properties in photo-oxidation/ reduction reactions under visible-light. The OVs content could be controlled by adjusting the sulfur source amount, and the optimal OV(0.9)-Bi2WO6 with suitable OVs had a high photocatalytic activity with 97.6% of MO removal and 88.2% of Cr(VI) removal efficiency. Density functional theory (DFT) calculations verified that the OVs in Bi2WO6 could induce a new defect level to decrease the bandgap energy and accelerate the carrier separation/migration. Furthermore, the possible photocatalytic mechanisms for MO degradation and Cr(VI) reduction over the OV-Bi2WO6 were proposed, respectively. The present work helped us to better understand the enhancement mechanism of OVs in Bi-based semiconductors and paved the way to develop high-performance photocatalysts for environmental remediation.