| Highly-orderd Nanocrystalline TiO2 porous films with high specific surface area and high thermal stability were synthesized using organic surfactant(PEG, triblock polymer-EPE)as template. The physical and chemical changes during the sol-gel process were analyzed systematically and the condition for the formation of sol-gel was determined. The effects of processing parameters on the microstructure and properties of the titania films were studied and the templating mechanism of the PEG and EPE was discussed fundamentally. The addition of complexing agent effectively restrains the intensive hydrolysis of TEOT, which is helpful to get more stable titanium sol-gel. The nanocrystalline titania films from sol-gel with DEA are highly porous with high surface area (72.5m2/g). The size and density of pores are related to the quantity and molecular weight of the template. The diameter of pores in the films synthesized by PEG with low molecular weight is smaller and the density is higher. Comparatively, the distribution of the pores becomes looser with the high molecular agent. Both of the diameter and distribution of the pores increase with the content of PEG. nH2O/nTEOT and the content of complexing agent have effects on the morphology of the films. The heat-treatment is critical to control the microstructure of the films. The experiment shows that it is very important to prepare porous films at lower heating rate.During the preparation of the films, PEG operates by Liquid-crystal-Templating mechanism and Cooperative formation mechanism.Highly ordered porous naocrystalline TiO2 films were synthesized using triblock polymer EO20PO70EO20 as template and TiCl4 as precursor at non-aqueous condition. The pores in the films are uniform with diameter about 10 nm. The inorganic wall with thickness of 10 nm enhances the stability of the porous structure. The BET specific surface area of the film is 150 m2/g, which endues the films with excellent photo-electro-chemical properties. |
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