Oxygen vacancy induced electron traps in tungsten doped Bi2MoO6 for enhanced photocatalytic performance

Abstract

We investigated the structural and photocatalytic properties of tungsten-doped Bi₂Mo_1−xW_xO₆ (x = 0, 0.01, 0.03, 0.05 and 0.10) nanosheets. X-ray diffraction patterns showed that the preferred growth orientation of the (020) and (060) planes was suppressed with the increase of tungsten doping. Scanning electron microscopy photos showed that the thickness of the Bi₂Mo_1−xW_xO₆ nanosheets gradually diminished when x increases. UV-vis spectra showed that the optical band gap of Bi₂Mo_1−xW_xO₆ was gradually enlarged with the increase of tungsten doping. X-ray photoelectric spectra of the Bi₂Mo_1−xW_xO₆ revealed that the doped tungsten ions successfully replaced some Mo ions in the Bi₂Mo_1−xW_xO₆ nanosheets and the valence band maximum of the different Bi₂Mo_1−xW_xO₆ also decreased gradually. When the doped tungsten increased from 0.01, 0.03, and 0.05 to 0.10, the photocatalytic performance of rhodamine B and tetracycline removal was enhanced compared with pristine Bi₂MoO₆ nanosheets. However, the Bi₂Mo_0.95W_0.05O₆ sample possessed the best photocatalytic performance, not the Bi₂Mo_0.90W_0.10O₆ sample, which could be explained by the effect of the oxygen vacancy induced electron traps.