Synthesis And Microstructure Properties Of SiO₂/TiO₂/WO₃Porous Photocatalytic Materials

With the continuous improvement of people’s living standards, water pollution and indoor air pollution has been increasingly attracting the attention of people. TiO2has been widely used in the field of waste water treatment, air purification and sterilization self-cleaning owing to its strong photocatalytic ability. The band gap energy of TIO2can be reduced and light response range of TiO2can be expanded by combination of WO3and TiO2so as to make full use of the sunlight. Moreover, porous photocatalytic materials have more excellent photocatalytic performance because of its high specific surface area and pore volume.In this paper, focusing on the synthesis and properties of the SiO2/TiO2/WO3porous photocatalytic materials, the following contents were mainly studied:Preparation of TiO2-SiO2composite aerogels through the pre-modification ambient pressure drying method, synthesis of WOx/TiO2and SiO2/(WOx-TiO2) composite photocatalytic materials by the hydrothermal method, preparation of (WOx-TiO2)/(TiO2-SiO2) mesoporous composite photocatalytic material through adsorption method, as well as preparation and characterization of (SiO2aerorgel)/(WOx-TiO2) composite air purification coatings. The microstructures and properties of the products were studied by SEM, TEM, XRD, UV-vis spectroscopy and N2adsorption/desorption method. The photocatalytic activity of the material was analysized by photocatalytic degradation Rhodamine B experiment, and the adsorption/photocatalytic degradation ability of the prepared air purification coatings for formaldehyde gas was analyzed.The results show that specific surface area and pore volume of the TiO2-SiO2treated by hexamethyldisiloxane (HMDSO) was higher than that treated by decamethyltetrasiloxane; When the volum rate of HMDSO and TMCS and TiO2-SiO2composite sol were12:6:120and12:12:120, the specific surface area of composite aerogels prepared under the modified conditions were492.12m2/g and553.38m2/g, the pore volume were2.79ml/g and2.85ml/g, respectively, and the photocatalytic degradation rate for Rhodamine B solution (CRhB=5×10-6mol·L-1) could attain to more than96%.WOx/TiO2and SiO2/(WOx-TiO2) composite photocatalytic materials were prepared by hydrothermal method, and the effects of different adding amount of SiO2aerogel and templating agent P123as well as hydrothermal reaction temperature and time on the structure and performance of mesoporous WOx/TiO2composite photocatalytic material were investigated. The results indicate that, when adding amount of WOx was2mol%, the band gap energy Eg2moL%of WOx/TiO2composite photocatalytic material was2.44eV, and the visible light photocatalytic degradation rate for Rhodamine B solution was90.15%; When the molar mass of P123was0.5mol%or SiO2aerogel adding amount was0.1g, the degradation rate of WOx-TiO2and SiO2/(WOx-TiO2) composite photocatalytic materials for S×10-6mol·L-1Rhodamine B solution were83.66%and87.18%, respectively.Mesoporous (WOx-TiO2)/(TiO2-SiO2) composite photocatalyst materials were prepared by adsorption method, and the effects of the addtion amount of acetyl acetone and glacial acetic acid on the WOx-TiO2composite sol were analyzed. The results indicate that the specific surface area of the prepared (WOx-TiO2)/(TiO2-SiO2) mesoporous composite materials were245-287m2/g, and the pore volume was0.17-0.28ml/g after ambient pressure drying at90℃. When the mole fraction of WOx was1.0mol%, the product had strongest photacatalytic ability with the degradation rate74.44%for CRhB=5×10-6mol·L-1Rhodamine B solution. When doing repeated photocatalytic degradation experiment, degradation rates were successively as follows:74.44%,80.67%,64.17%, and64.96%.Composite air purification coatings with SiO2aerogel and WOx-TiO2composite photocatalyst particles as the main functional inorganic adding phase were prepared, and the adsorption/photocatalytic degradation ability of the (SiO2aerogel)/(WOx-TiO2) composite air purification coatings on formaldehyde gas was investigated. The results indicate that when mass fraction of adsorption/photocatalyst in the air purification coatings was5wt%and mass rate of SiO2aerogel and WOx-TiO2composite photocatalyst particles were2:1and1:1, the obtained coatings has better adsorption/photocatalytic degradation performance, with69.6%for Rhodamine B, and the adsorption/photocatalytic degradation rate could reach to84.62%within3h for formaldehyde.