Preparation And Properties Of Mesoporous Titanium Dioxide

Mesoporous materials have attracted a lot of attention due to their particular characteristics such as the size uniformity,ordered arrangement and continuous orderliness of the mesopores,as well as the huge surface areas.The foregoing characteristics and the potentials of mesoporous materials in the catalysis,adsorption, separation,and preparation of nanomaterials have make it a researching hotspot in the material science field.Mesoporous TiO₂ is widely regarded as a photocatalyst with high activity due to its lager surface area and pore volume,as well as better adsorption and light absorption performance compared with those of conventional TiO₂ powders.In the present paper,anatase mesoporous TiO₂ was prepared by a hydrothermal process with Ti(OBu)₄ as a starting material and octadecylamine as template.The effects of the hydrothermal temperature,hydrothermal time,and calcination temperature on the mesoporous structure of the sample have been investigated.The samples were characterized with XRD,TEM,N₂ adsorption-desorption measurements, DTA-TGA,and UV-vis diffuse diffraction.The results showed that the mesoporous sample possessed the largest specific surface area of 201.3m²·g^-1,a pore volume of 0.259 cm³·g^-1,and an average pore size of 4.3nm when the hydrothermal temperature was 150℃,the hydrothermal time was 20h,and the calcination temperature was 450℃.Its photocatalytic reaction constant for degradation of MO was 0.096 min^-1,which was larger than that of P25.Fe(Ⅲ)doped mesoporous TiO₂ was prepared by a solvothermal method with Ti(OBu)₄ as starting material and octadecylamine as template.The samples were characterized with TEM,XRD,N₂ adsorption-desorption measurements,DTA-TGA, IR,XPSand UV-vis diffuse diffraction.It was found that the wormhole-like mesoporous structure was actually composed of random arrangement of TiO₂ nanocrystals.The mesoporous sample with a Fe/Ti atomic ratio of 1.0%possessed a specific surface area of 151.2m²·g^-1,a pore volume of 0.147 cm³·g^-1,and an average pore size of 3.9 nm.The Fe dopant had effects on the photocatalytic property of Fe doped mesoporous TiO₂.The Fe dope sample with a Fe/Ti atomic ratio of 1.0% showed the largest photocatalytic reaction constant for degradation of MO,which was 0.096 min^-1 and much larger than that of the undoped sample.It should be ascribed to the fact that Fe doping could narrow the bandgap of TiO₂ and inhibit the recombination of the photogenerated electron and hole.However,a larger amount of Fe dopant(＞1.0 at.%) showed detrimental effect on the photodegradation of MO.