bismuth-oxychloride and bismuth-oxybromide

In this study, bismuth oxyhalide (BiOXs (XCl, Br, I)) semiconductors were prepared by a simple solvothermal method, with ethanol serving as solvent and a series of tetrabutylammonium halide surfactants as halogen sources. Under identical synthetic conditions, BiOBr was more readily constructed into regular flower-like hierarchical architectures. The photocatalytic properties of the materials were studied by monitoring the degradation of rhodamine B (RhB), with visible light absorption, and colorless salicylic acid (SA). It was found that both RhB and SA were rapidly degraded on the surface of BiOBr. BiOCl was rather active for the degradation of RhB, but ineffective toward the degradation of SA. However, neither RhB nor SA could be degraded effectively in the case of BiOI. Further experiments such as UV-visible spectroscopy and detection of OH and O2(-) radicals suggest that the electronic structure of the BiOX photocatalysts is responsible for the difference in their activities.

Topics: Bismuth; Ethanol; Photolysis; Rhodamines; Salicylic Acid; Semiconductors

This study reported, for the first time systematically, photodegradation of Rhodamine B (RhB) in aqueous solution over BiOCl and BiOBr semiconductors. Under visible light irradiation (λ>400 nm, λ>420 nm and λ=550±15 nm), RhB adsorbed on the surface of BiOCl and BiOBr was photosensitized and decomposed effectively over unexcited BiOCl and BiOBr. The degradation of Methyl Orange (MO) and Methylene Blue (MB) over BiOCl and BiOBr was investigated as well, and the results were compared with RhB photodegradation. It was found that MB molecules having the lowest LUMO could not be degraded by this process. Utilizing the quantum chemical calculation (Gaussian 03 program), the relationship between frontier orbital energy of selected dye molecules and photodegradation rate was established for the first time in this study.

Topics: Bismuth; Light; Photochemical Processes; Rhodamines; Semiconductors