Synthesis And Photocatalytic Activity Of Mesoporous TiO₂-WO₃

Mesoporous materials have many unique properties.Since the U.S.company Mobil reported the M41 series of mesoporous materials, mesoporous materials have quickly caused great concern from the international materials science and related areas. Because it shows the great value in adsorption, catalysis and many other fields as its small pore size and big surface area.TiO₂ is an important semiconductor photocatalytic materials.For the photocatalytic reaction, mesoporous TiO₂ with a large surface area can be conducive to organic adsorption,and it can accelerate the reaction. Mesoporous TiO₂ has unique pore structure to benefit the spread of the reactants and products, and it has a positive effect for improving the catalytic activity .TiO₂ are wide band gap materials which can be excitated by a shorter wavelength UV.Band gap is 3.2ev, while the ultraviolet part in the solar spectrum is only about 5%.It can resulte in photocatalytic decomposition efficiency relatively low, and the practical application of value is not high. In order to improve its photocatalytic properties, researchers do a lot of work to doping TiO₂.Based on the recent progress in the field of mesoporous materials,the synthesis of mesoporous WO-3-TiO₂ was investigated in this paper. The influence of the baking temperature and baking time for mesoporous WO-3-TiO₂ was investigated in this paper. The photocatalytic experiments were carried out. TiO₂ doping metal oxides can enhance the solar energy conversion efficiency. This thesis is divided into two parts.Firstly, the synthesis,characterization and photocatalytic experiments of mesoporous TiO₂ materials. In this paper, TiCl₄ is a raw material, and sodium dodecyl sulfate (SDS) is a template. Mesoporous TiO₂ materials are prepared by hydrothermal. TG-DTA, XRD, TEM, SEM analysis shows that the best temperature of removal template is 450℃; N2 adsorption - desorption isotherms of samples is the Langmuirâ…£type which is a typical mesoporous structure of adsorption isotherm; XRD analysis shows that the crystal structure transforms from anatase to rutile phase with the temperature rising; TEM shows that the sample was uniformly dispersed spherical particles about 10-20nm particle size; photocatalysis was found that mesoporous TiO₂ photocatalytic properties are higher than TiO₂ powder photocatalytic properties. Acid Red 3R degradation rate could reach 95% above after sunlight exposure in 40min. Secondly, synthesis and photocatalytic properties of the mesoporous WO-3-TiO₂ composite materials. TiCl₄ and NaWO₄·2H₂O are raw materials, and sodium dodecyl sulfate (SDS) is a template. Mesoporous WO-3-TiO₂ materials are prepared by hydrothermal. It also can be found that the addition of W element has a great impact in the photocatalytic properties of composite powders.We can see that the sample particles are spherical which are about 20nm from TEM picture.It was found that the doping W 2% is the best for the photocatalytic capacity.