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

We investigated the structural and photocatalytic properties of tungsten-doped Bi2Mo1−xWxO6 (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 Bi2Mo1−xWxO6 nanosheets gradually diminished when x increases. UV-vis spectra showed that the optical band gap of Bi2Mo1−xWxO6 was gradually enlarged with the increase of tungsten doping. X-ray photoelectric spectra of the Bi2Mo1−xWxO6 revealed that the doped tungsten ions successfully replaced some Mo ions in the Bi2Mo1−xWxO6 nanosheets and the valence band maximum of the different Bi2Mo1−xWxO6 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 Bi2Mo0.95W0.05O6 sample possessed the best photocatalytic performance, not the Bi2Mo0.90W0.10O6 sample, which could be explained by the effect of the oxygen vacancy induced electron traps.