The Preparation And Photodegradation Of BiOl And Composites

In this paper, the BiOI and composites were prepared by low-temperatureprecipitation. The obtained products were characterized by a range of methods suchas X-ray powder diffraction (XRD), field mission scanning electron microscopy(FESEM), transmission electron scanning microscopy (TEM), UV-Vis-NIRspectrophotometer (DRS), fluorescence spectroscopy (PL), X-ray photoelectronspectroscopy (XPS) and nitrogen sorption, respectively. The photocatalyticperformances of the samples were evaluated by the degradation of organicpollutants. The influences of reaction conditions on the composition, morphology,optical property and photocatalysis of the products were systematically studied. Thegrowth mechanism of varies microstructures and the photocatalytic factors also werediscussed. The main research work is listed as the following parts:1. The plate, hollow and flower-like microstructures of BiOI have been preparedthrough a facile precipitation route in a water–ethanol mixed solution. Theformations of microstructures were affected by adjusting the amounts of reagents,the volumes ratios of water-ethanol solvents and the contents of assistants. Thespecific surface areas and the cumulative pore volumes of these various structures ofBiOI samples were calculated (10.8m2g-1,38.8m2g-1, and45.2m2g-1respectively).And the optical properties of the different structures were counted from the diffusereflectance spectra (1.63eV,1.68eV, and1.72eV). We can learn that the flower-likesample have the lowest PL intensities and would have the outstanding property ofphotocatalysis among these different BiOI structures, since the lower PL intensity indicates a lower recombination rate of excited electrons and holes. Thephotocatalytic experiments of RhB were performed using the as-synthesized BiOIsamples in this article in order to discuss the adsorption and photocatalytic activity.The high photocatalytic activity of the flower-like microspheres is associated with thestrong adsorptive capacity to the dye molecules (80%) and the efficient utilization ofvisible light, and forms bright contrast with that of other photocatalyst.2. The BiOBr nanosheets/BiOI Microspheres were prepared by a modifiedprecipitation rout and characterizatied by XRD, FESEM, TEM and XPS. The specificsurface area and pore sizes of products are further characterized by N2adsorption/desorption isotherms. The BiOBr nanosheets/BiOI Microspheres and theBiOI-BiOBr microspheres, BiOBr and BiOI have specific surface area of28.34m2g-1,24.57m2g-1,20.20m2g-1and18.72m2g-1, respectively. The optical properties ofthe as-prepared samples are measured by UV-vis absorption spectra and areestimated to be2.04eV,1.96eV,2.83eV and1.67eV, respectively. The BiOBrnanosheets/BiOI Microspheres in this study possess the lowest PL intensity amongfour as-prepared samples and lowerest recombination rate of excited electrons andholes. It was found that the morphologic formation of the products is greatly affectedby the growth time of crystal, the mixed solvent’s ratio and the CA’s concentration inthe reaction. The photocatalytic performance of the as-prepared photocatalyst wastested by degradation of typical dyes, including RhB, MO and phenol. It was obviouslyfound that the BiOBr nanosheets/BiOI Microspheres exhibited higher photocatalyticactivity than other three samples.