Thermal Stability, Microstructure and Photocatalytic Activity of the Bismuth Oxybromide Photocatalyst

• Published in: Chinese journal of chemistry 2012-03, Vol.30 (3), p.721-726
• Main Author: 余长林 周晚琴 余济美 操芳芳 李鑫
• Format: Article
• Language: English
• Subjects: acid orange II; bismuth oxybromide; Light; Microstructure; Photocatalysis; photocatalytic activity; Scanning electron microscopy; Spectrum analysis; structure-activity relationships; transition states; X射线衍射; 光催化活性; 光触媒; 可见光照射; 微观结构; 扫描电子显微镜; 热稳定性; 铋
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.201280018

Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24031Brll at around 750 ℃ and the formed Bi24O31Br11 can further convert to rod-like a-Bi203 at around 850℃. The prepared compounds were characterized with X-ray diffraction （XRD）, N2 physical adsorption, scanning electron microscopy （SEM）, and UV-Vis diffuse reflectance spectra （DRS）, respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange Ⅱ under both visible light （λ〉420 nm） and UV light （λ=365 nm） irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and a-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order： BiOBr/Bi24O31Br mixture 〉 BiOBr 〉 Bi24031Br〉a-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.