Synthesis And Characterization Of Tungsten Trioxide Mesoporous Materials

WO3materials have good performances in the fields of information storage, information functional materials, magnetic materials, catalysts as well as display devices because of their unique optical, electrical and magnetic properties. At present, WO3has become one of the most popular functional oxided for the scholars at home and abroad. The performances of WO3materials have a close relationship with their morphology, microstructure and composition, thus it is valuable to study the preparation for WO3with different apparent morphologies or internal structures, to further enhance its performances.Mesoporous materials have attracted the attention of scientists in various countries, its huge specific surface area and pore volume, narrow pore size distribution as well as rules with adjustable ordered pore structure, have important applications in many fields including catalysis, separation and adsorption. So many countries and research institutions are investing huge funds to carry out the study of mesoporous materials. In this paper, we consider to optimize the functions of WO3via nano-modification to obtain mesoporous WO3with a larger surface area and pore volume, which further enhance its performances and expand its applications.In this paper, Na2WO4.2H2O was used as an inorganic tungsten source, non-ionic surfactant P123(EO20PO70EO20) as templating agent and a mesoporous structure of WO3powder were successfully prepared in strong acid environment via a soft template method. Product samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), N2adsorption-desorption (BET), and UV-visible diffuse reflectance spectroscopy (UV-vis). On the basis of our preliminary results of the preparation of WO3powders, we discussed the effect of the precursor concentration, the additive amount of P123and the hydrothermal conditions (hydrothermal temperature, pH value) on the product structure, morphology and absorbance activity. We have obtained absorbance optical activity of WO3mesoporous materials by improving their specific surface area.The results analysis show that:1. The precursor concentration increases, WO3mesoporous powder crystallinity decreases; the mesoporous powder of WO3with precursor concentration of1.0mol/L obtains good dispersion, and possesses needle-like basic particles, whose specific surface area, pore volume and pore size are76.77m2/g,0.22cm3/g and11.49nm, respectively; it has showed better absorbance activity than the other two samples.2. Different additive amount of P123has no significant effect on the crystalline phase and degree of crystallinity for WO3powders. Samples with P123are of typical mesoporous structure, and P123dosage of7.5*10-4mol/L are with the largest surface area compared with other samples, which shows a higher absorbance activity.3. Hydrothermal temperature increases, the grain size of WO3mesoporous powder increases. the crystalline phase transforms from the hexagonal phase to cubic phase gradually; sample with the hydrothermal temperature of120℃obtains larger specific surface area and higher absorbance activity. The increasing of pH value prompts the WO3crystals to a more advanced crystal growth; sample with the pH value of1.0acquires larger specific surface area and higher absorbance activity.