Preparation And Characterization Of Mesoporous TiO₂ Materials And Their Photocatalytic Activity

Mesoporous titanium was usually used in the form of nanoparticles in suspension for high catalytic surface area and activity.They can effectively improve properties in photocatalytic applications for environmental remediation.The study show that mesoporous titanium has higher catalyst activity than nanometer titanium dioxide.Firstly,using cationic surfactant cetyltrimethylammonium bromide(CTAB)as the template,TiO₂ and V/Ce/F-TiO₂ mesoporous materials were synthesized by sol-gel method and characterized by X-ray powder diffractometry(XRD),N₂ absorptiometry, transmission electron microscope(TEM),thermal analyses(TG/DTA) and UV-vis DRS.By systematically studying the influence of the synthesis parameters such as gelling time,aging temperature and aging time,we have established optimal conditions for reproducible synthesis of mesoporous titania.Specific area up to 189m²Â·g^-1 was obtained with average pore size in the rang of 3.1-5.1 nm.The mesoporous structure of pure TiO₂ could be destroyed by calcination of template at 450℃.However,V/Ce/F-TiO₂ removed template by calcinations has the mesoporous structure,which suggests that the mesoporous structure can be stabilized by the doped ions.Shift of the adsorption edge to visible light was found for the doped mesoprous TiO₂.Mesoporous photocatalytic TiO₂ films were prepared via a simple method that involves dip-coating of ITO glass into an organic/inorganic sol followed by calcination of the coating at 350℃.By systematically studying the influence of the synthesis parameters such as mass of doped CTAB,the viscosity of sol,aging temperature and aging time,we have established optimal conditions for reproducible synthesis of mesoporous titania films.They were characterized by XRD,SEM, TEMand N₂ adsorption-desorption isotherm.The results show that the properties included high surface area(166 m²Â·g^-1) and narrow pore size distribution ranging from2 to 10 nm,active anatase crystal phase and homogeneity without crack in large scale.The thickness of TiO₂ layers was uniform at approximately 1.0μm.Using the TiO₂/ITO as working electrode characterized by electrochemical analyses,the photoelectrocatalytic system with three kinds of electrodes(Pt as counter electrode and Ag/AgCl as reference electrode) is built.Dye wastewater was one of refractory industrial wastewater,especially methyl orange dye wastewater.We systematically studied important factors influencing the degradation of methyl orange by the photoelectrocatalytic method,such as the bias potential,pH value,quantity of catalyst,initial methyl orange concentration and electrolyte,and founded optimal conditions for degradation of methyl orange.Then we studied different sample under the optimal conditions.The effects of pH,bias potential,initial methyl orange concentration,quantity of catalyst on the photoelectrocatalytic reaction rate of methyl orange were investigated. The global kinetics was described by an exponential equation derived as C=C₀ exp(-1.6046C₀^-0.7169E^0.3175Q^1.4692t).The calculated result was close to experimental result.