Fabrication Of BiOX (X=CI, Br, I) Nanostructure Microspheres And Their Photocatalytic Properties

Industrial production such as textile, papermaking, textile printing, paint, and leather, need to usea lot of industrial dye, resulting in a lot of colored wastewater of high concentration, in which oftencontains a lot of toxic organic matter. The discharge without processing or treatment of incomplete hascaused serious pollution of water resource. Organisms may be induced mutation in the body after drinkingcontaminated water. Therefore, removing the toxic substances in the drinking water is more and moreimportant. Photocatalysis reactions can degrade organic pollutants in water into H2O and CO2smallmolecules or non-toxic organic matter and purify effectively. Research has shown that semiconductorphotocatalysis can thoroughly remove organic pollutants, especially some biological toxic substances thatare difficult to degradation. Photocatalysis is one of the most promising sewage purification technologies.Therefore, research of advanced semiconductor photocatalytic materials has attracted much attention.Bismuth oxyhalide BiOX （X=Cl, Br, I） as a new type of semiconductor photocatalytic materialsis developed in recent years. They exhibit excellent photocatalytic properties due to layered crystalstructure and suitable band gaps and gradually become the hot topics in the field of material science andcatalytic science. At present, the research of this new type photocatalyst is still not deep enough andinsufficient system. The preparation methods most need high temperature and pressure. The morphology ofproducts is not uniform and difficult to achieve controlled synthesis. This paper mainly does the followingwork to solve above problems:1. First of all we main research bromine bismuth oxide （BiOBr）, using a simple solvothermalmethod by adjusting the surface active agent polyvinylpyrrolidone （PVP）, heating temperature, and solventto control the morphology, structure and size of the sample. Results showed that when0.05–0.1g PVP wasadded, BiOBr products appeared in the shapes of two different flowers composed of nanoslices with thethickness of about10nm under120°C using ethylene glycol （EG） as solvent. While0.2g PVP was added,the products were regular and well-dispersed BiOBr hierarchical microspheres with a uniform size about2μm. The other BiOBr products were also prepared under the same experimental conditions except a highersolvothermal temperature （150C）. The increasing of PVP amount from0.05to0.3g results in the changeof sample from spherical into flat ball and final flower-like morphologies. Temperature main influences thereaction speed and the amphiphilic PVP influences the thickness of lamella and the distance betweennamosheets. However, while using deionized water as solution instead of EG, we only find nanosheet ofBiOBr, which shows the directive interaction of EG molecules with BiOBr particle interfaces is responsiblefor the formation of BiOBr hierarchical structures. So it is the cooperative directing effect of EG and PVPmolecules that determines the ultimate morphology of the obtained BiOBr nanostuctures. Photocatalyticdegradation properties of the as-prepared BiOBr on the degradation of methyl orange （MO） were tested, inwhich MO was used to simulate organic wastewater.2. Use the same method to prepare BiOI and BiOCl. The results show that the samples of BiOIhave a good dispersion and uniform size when add0.05g PVP. The ultraviolet and visible spectroscopy （uv-vis） shows that both absorption edges of sample are in visible light region. And photocatalytic textsdisplay samples of BiOI have outstanding photocatalytic properties. Yet such preparation method for BiOCl,only when the temperature increases to180°C, can obtain the inerratic spherical morphology. The uv-visshows that three-dimensional BiOCl only have response to ultraviolet light. But it is worth mentioningBiOCl show better photocatalytic activities than TiO₂（P25） generally.