Preparation Of WO₃/TiO₂Hollow Microspheres With Assistance Of F127and Their Photocatalytic Property

Nano-structured titanium dioxide （TiO₂） is a new type of semiconductor oxide nanofunctional materials, have a lot of the physical and chemical properties compared to thegeneral TiO₂, the special nature of the optical, mechanical, electrical, thermal, magnetic, etc..Its performance for the large specific surface area, surface-active, good light-absorbingproperties, low melting point and good thermal conductivity properties, and gooddispersibility. Because of these characteristics of titanium dioxide, as a catalyst or carrier, thephotoelectric conversion material and coating materials, used in the chemical industry,environmental protection, cosmetics, paint, paint pigments and other fields. Titania hollowmicrospheres as the excellent performance of photocatalytic materials, the advantages such asoxidation ability, physical and chemical properties of stability, non-toxic, response to visiblelight, is ideal semiconductor material in the photoelectrochemical system, direct use of thesunlight or the ordinary light to purify environment and water resources, therefore in the fieldof photocatalysis has been extensively studied.But the band gap energy level of the titanium dioxide is3.2eV, forbidden band is wider,prone to recombination of electrons and holes, and exhibiting high catalytic activity onlywhen a sufficient intensity of ultraviolet light or near-ultraviolet excitation, while theultraviolet light account for only a small part of the sunlight, and inefficient use of solarenergy, to improve TiO₂on the utilization of sunlight, increases the photocatalytic activity isto solve the main problems.Tetrabutyl titanate in the laboratory for the titanium source, the use of alcohol thermalmethod, has been prepared without template titanium dioxide microspheres, method ofoperation is simple, but the the prepared microspheres small surface area, surface propertiesand photocatalytic properties is not high. Therefore, this thesis template copolymer F127as atemplate for preparing titanium dioxide hollow microspheres, and conducted in-depthdiscussion on the role of F127. And in order to improve the photocatalytic activity of TiO₂,WO₃incorporated into the TiO₂hollow microspheres, delve into the characteristics ofWO₃-TiO₂hollow microspheres on the morphology and the performance nature, comparedwith pure TiO₂hollow microspheres.The main contents and conclusions are as follows:1. Experiment to the triblock copolymer F127as a template, tetrabutyl titanate astitanium source alcohol thermal Method prepared titania hollow microspheres is composed ofnumerous cellular pore composition, having a good morphology, size uniformity, The larger pore size, specific surface area larger features. Explore the of copolymer F127dosage of themorphology and properties of the microspheres obtained when the copolymer F127dosage n（PF127）: n （Ti）=0.5%:1, microsphere morphology, pore size distribution, specific surfacearea. Description F127in the preparation process, helps to expand the channel, to control themorphology of the microspheres uniformly, increasing the ratio of surface area.2. In depth discussion of the main factors affecting the morphology of the titania hollowmicrospheres, the molar ratio of the reactants water and tetrabutyl titanate, pressing time,pressing temperature in varying degrees affect the morphology. By regulating the molar ratiobetween deionized water and tetrabutyl titanate, so that the hydrolysis and polycondensationreactions to achieve more appropriate speed to create the conditions for the formation ofhollow microspheres. The reaction temperature and the pressing time in the titania hollowmicrosphere formation process plays a key role in the level of the reaction temperature andthe pressing time is directly determines whether or not possible to obtain an ideal sphericalstructure and properties. Preparation of TiO₂hollow microspheres Experimentalcharacterization analysis of appropriate conditions for the pressing time for4h, the reactiontemperature of190°C, n （H2O）: n （Ti）=1:1.3. Manufactured by the experiment, the microspheres of titanium dioxide is prepared inthe optimum conditions calcined through different temperature calcination to remove theorganic component of the microspheres, samples were characterized, belong to the anatasetype titanium dioxide microspheres, at elevated temperatures not changed its polymorphs,when the temperature is too low, the organic component of the microspheres is notcompletely removed, stacked within the pores of the microspheres, so that a small specificsurface area, when the temperature is too high, the grain growth, resulting in the collapse ofthe mesoporous structure, than surface area decreases. Therefore come to the surfaceproperties of the best roasting temperature of400°C.4. TiO₂hollow microspheres in copolymer F127as a template Titania HollowMicrospheres were prepared by the alcohol thermal method based on WO₃doping probe intothe characteristics of WO₃-TiO₂hollow microsphere morphology performance by doping ofWO₃, WO₃-TiO₂hollow microspheres and pure TiO₂hollow microspheres light UV-visiblediffuse reflection absorption spectroscopy doped WO₃absorption spectra broaden theultraviolet region to the visible region, which is due to TiO₂the band gap of3.2eV, WO₃bandgap of2.8eV, doped TiO₂and lower band gap, improve the optical response.5. The photocatalytic performance analysis, relative to pure TiO₂hollow microspheresWO₃-TiO₂photocatalytic activity of the hollow microspheres improved doping and calcination temperature on the catalytic activity by experimental samples doped WO₃Whenthe doping amount of2%, the best photocatalytic activity of WO₃-TiO₂hollow microspherescalcined at400°C when the best photocatalytic activity.