Synthesis And Properties Of Tungsten Oxide Nanoparticles

Tungsten oxide(WO3)is one of the important transition metal oxides. As a wide bandgap n-type semiconductor, WO3 is of great interest due to its applications in gas sensors, photocatalytic materials, flat panel displays and electrode materials. It is well known that the size and morphology of nanomaterials are crucial issues for their properties. Therefore, controlling the shape and structure of the materials is one of the most challenging issues presently faced by many chemists.In this paper, WO3 were synthesized with different morphologies and its formation mechanism had been primarily discussed. The obtained powders were characterized by XRD, SEM and TEM.Many n-type semiconductor can be used as photocatalysis, such as TiO2, ZnO, Fe2O3, CdS and WO3, and so forth. WO3 has similar bandgap and structure with TiO2 and it also has good photocatalytic properties. The effect to the decomposition of organic pollution in sewerage is better. Considerable research has been carried out on the development of chemical sensors based on semiconductor metal oxides such as SnO2, ZnO and TiO2. WO3, as an n-type semiconductor, has been proven to be a highly sensitive material for the detection of both reducing and oxidizing gases. In this paper, the gas sensing and photocatalytic properties of WO3 nanoparticles were studied. The main conclusions are as follows:(1) Rectangular, plate-like, rod-shaped and spherical WO3 nanopowders were prepared by hydrothermal method in the presence of different assistant agents. The morphology and structure of the WO3 nanoparticles have been characterized by transmission electron microcopy (TEM), scanning electron microcopy (SEM) and X-ray diffraction (XRD). In the investigation of the relationship between the product morphology and the assistant agents, we found that the assistant agent had an integrative effect on the morphology of the products.(2). The gas sensing properties of tungsten oxide are related to its morphology. In our work, we mainly discuss the gas sensing properties of tungsten oxide with different morphology in detecting ethanol and acetone. The results showed that the sensitivity of the sensors changed with the working temperature, concentration of gases and morphologies. It is possibly that the ethanol and acetone gas can react with the negatively charged oxygen and release a trapped electron at the same time. These electrons can reduce the resistance of the gas sensors.(3) The photocatalytic properties of tungsten oxide are also related to its morphology. In the work, photocatalytic reaction of methylene-blue in WO3 powder suspension irradiated by ultraviolet lamp was studied and the degradation rate of the methylene-blue using WO3 with different morphology as photocatalysis was also studied. We also studied the influence of WO3 which had best photocatalytic properties on the wastewater from gasolene. The result showed that the WO3 with different morphologies showed different photocatalytic activities for the degradation of methylene-blue under UV. The WO3 with hollow structure had better photocatalytic property to the wastewater from gasoline.