The effects of Br dopant on the photo-catalytic properties of Bi2WO6

• The performance is significantly enhanced with Br doping for Bi2WO6 powders.
• The structural stability and electronic properties are studied by the first-principles method.
• The photocatalytic mechanism is analyzed by the electronic structures.

We present an experimental study on photocatalysis of pure and Br-doped Bi2WO6 powders, including photo-degradation of Rhodamine B, UV–vis absorption spectra and photo-luminescence spectrum. The obtained results indicate that Br-doped Bi2WO6 powders exhibit preferable photocatalytic activity than pure Bi2WO6. Then, the structural stability and the electronic properties of Br-doped Bi2WO6 are studied by employing the first-principles method, and a promising improvement of photo-catalytic activity is found in the visible-light region after doping, which is consistent with the experimental results. The BrII-doped structure is found to be more preferred, nevertheless all the three types of doping can narrow the band gap of Bi2WO6 pronouncedly, and thus the availability of solar energy increases consequently with the doping. On the other hand, the doping of Br results to smaller electron effective mass and induces impurity levels in gap, which is in favor of the carrier's transfer and the decrease of electron-hole recombination respectively.

The UV–vis absorbance spectra are shown in (a), while the calculated optical absorption spectra are shown in (b) as a contrast. The experimental result is consistent with the calculation, that is, red-shifts are generated for both of them, which suggests that the Br-doped Bi2WO6 is more effective in absorbing visible light and thus the photocatalytic activity under visible light will be enhanced by the doping.Figure optionsDownload as PowerPoint slide