Hydrothermal Synthesis And Properties Study Of One-Dimensional Nanomaterials Based On Tungsten And Titanium

In recent years, with the rapid development of microelectronics and communication industry, the fast growing up of one-dimensional (1D) nanomaterials research was stimulated. It is very significantly important for the development and application of 1D nanomaterials to seek new facile synthesis method, exploit new materials system and discover their special function.Nanomaterials based on tungsten and titanium is a kind of advanced materials with many potential applications. Tungsten oxide and titanium oxide with 1D structure has been paid tremendous attention because of their specific chemical structural properties and broad applications. Nanostructural tungsten oxide and titanium oxide are all n-type semiconductor with wide forbidden band, with excellent photocatalysis, and with application in disposal waste gas and polluted water.In this paper, first the synthesis methods, properties and applications of 1D nanostructural materials were recapitulated. We consider that combining the special condition of hydrothermal method with crystal growth property, 1D nanomaterials can be synthesized under control. Then, by simple hydrothermal method, we successfully synthesized tungsten oxide nanorods doped with transition metal-molybdenum and titanate nanotubes substituted by transition metals; we also prepared zinc tungstate nanorods doped with cadmium and cadmium tungstate nanorods doped with zinc. At the same time, all of these materials are characterized with the morphology, composition and other characteristics, and the influencing factors were analyzed, and the formation mechanism of these nanorods was discussed.There are many applications of tungsten oxide semiconductor materials, such as optical device, secondary battery, gas sensor, photocatalyst, et al., but some properties, such as photocatalytic property still need to be improved. When doped with impurity atoms and formed into 1D nanostructure, the structure and corresponding physical and chemical performance of tungsten oxide must be changed. In this paper, tungsten oxide nanorods doped with molybdenum were synthesized the first time by hydrothermal method. The morphology and size of tungsten oxide nanocrystals can be adjusted and controlled by assistant salts. The results show that the morphology and size of as-synthesized tungsten oxide nanocrystals are changed with salts concentration, that is, adjusting the concentration of assistant salts can control the morphology and size of products. The product was nanocrystal powder and 1D nanostructral rods when NaCl and sulfate was used as assistant salts, respectively. The size of tungsten oxide nanorods varies with different sulfate as assistant salt, the size of product was larger when assistant salt was Na₂SO₄, and otherwise, it was smaller when assistant was K₂SO₄. The results of experiment of photocatalyzing Methylene blue proved that the photocatalytic performance of tungsten oxide was remarkably improved by doping with metal atoms and being prepared into 1D nanostructure. Tungsten oxide nanorods had superior catalytic activity, and its photocatalytic effect was better than that of tungsten oxide nanopowder.TiO₂ is a very important photocatalyst in the past several decades because of its anti-corrosion ability to chemistry and light with low cost. The band gap of TiO₂ is wide(3.2ev), so the utilization ratio of sunlight is low; the complex ratio of electron-cavity is high, which results in the very low light quanta efficiency. Many methods had been used to change the properties of T1O2, and the photocatalytic performance was improved to some extent, but photocatalytic activity was not improved remarkably. So we can do some research on other compound of Ti, such as titanate, and by doping and preparing into ID nonstructural, maybe we can find high effect photocatalyst. In this paper, using anatase TiO2 nanopowder doped with transition element (Cu, Cr, Fe) as precursor, titanate nanotubes substituted by transition metals were first synthesized in situ with simple hydrothermal method. Titanate nanotubes substituted by transition metals was proved to be good photocatalyst. The photocatalytic properties of Titanate nanotubes substituted by transition metals Cu and Fe was improved remarkably.Zinc tungstate is a new type inorganic scintillator materials, and is mainly used to build electromagnetic calorimeter and high energy particle detector, but its luminescence efficiency is not high enough, so its properties need to be improved. Its properties can be improved by doping and preparing into ID nanomaterials. In this paper, zinc tungstate ID nanomaterials doped with cadmium were first synthesized by simple hydrothermal method. Results show that: the factors such as pH, react time, doped ratio and surfactant type all took effect on the morphology, size and optical performance. The photoluminescence ability was improved by doping with metal atoms.Cadmium tungstate is a new type inorganic scintillator material too. The former synthesis methods need high temperature, and difficult to control, and the product was bulk monocrystal of CdWCU. In small dimension system, the optical, electrical and thermal properties can be controlled by quantum confinement effect. In this paper, cadmium tungstate ID nanomaterials was first synthesized. And the factors such as pH, react time, doped ratio and surfactant type that affect the shape, size and optical performance were thoroughly investigated.