Ultrafine Layered Titanate Composite Nano-tio <sub> 2 </ Sub> Preparation And Properties Of,

The preparation of new nanometer and micrometer-sized material and the influence of particle sizes on the properties of the material are extensively studied in recent years in material science. In this Ph. D. dissertation, A series of layered titanates Na2Ti3O7,K2Ti4O9 with different particle sizes, especially the ultrafine layered Na2Ti3O7, K2Ti4O9 samples were fabricated. The influence of the sizes on the ion-exchange, alkylamine-intercalation, pillaring and exfoliation properties of the layered titanates was studied. The dissertation was mainly discussed as follows:Ultrafine layered K2Ti4O9 was successfully fabricated by stearic acid method, which were usually used for the preparation of nanoparticles. A series of layered titanates with differenet particle sizes were obtained by solid-state reaction using TiO2 with different average particle sizes as the raw material. It was shown that the solid state reaction was accelerated by decreasing the particle size of TiO2 and ultrafine layered titanates could be prepared by using nanometer-sized TiO2 as the starting material.The influence of the particle sizes of the titanates on the structure of products exchanged by H+, intercalated by alkylarm'ne and pillared by SiO2, Al2O3 was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravity analysis (TG), Fourier transform infrared spectroscopy (FT-IR) experiments. It was found that the ion-exchanging reaction was enhanced by the small-sized layered titanate and more water molecules were intercalated in the interlayer space of the small-sized layered K2Ti4O9. Compared with the large sized layered titantaes, the n-propylamine intercalated product with larger interlayer distance and much more propylamine content was obtained by using small sized K2Ti4O9. But in the n-butylamine intercalated system, due to the exfoliation, products of ultrafine K2Ti4O9 exhibited the small interlayer distance. Particle sizes of the titanates have different influencing regulation in SiO2 and Al2O3 pillared system, it was found that SiO2 pillared products with large interlayer distance and higher APS content was obtained using ultrafine layered titanate as the host material. In the Al2O3 pillaring system, the intercalation of the precursor of Al2O3 in the interlayer caused the decreasing of the charge density of the lattice, and the layer structure was partially exfoliated. And the thermally stabled TiO2 composite with high specific surface area and uniform pore size distribution could be obtained using ultrafine K2Ti4O9 as the hostThe exfoliation of ultrafine layered titanate was firstly found in our experiment. The exfoliated nanolayer was used as the building blocks for the fabrication of self-assembly nanoTiO2 multilayer. The exfoliation of ultrafine layered titanates in the AgNO3 solution was firstly found by the XRD experiment. The delaminated product was characterized by the X-ray photoelectron spectroscopy (XPS) and FT-IR.A rapid and simple method, stearic acid method was also developed to prepare nanostructured TiO2 composites. Microstructure of the samples was investigated by XRD, FT-IR, TEM and BET specific surface area measurement and the results were compared with those obtained by conventional sol-gel method. It was found that nanocrystalline powders with good dispersity, high crystallinity and large specific surface area were successfully prepared by stearic acid method. The anatase structured TiO2-SnO2 binary oxides could only be prepared by stearic acid method. The photocatalytic decomposition of methyl orange was used as a model system to determine the relative influences of the preparation method and the concentration of coupled oxides on the photocatalytic activities. It was found that TiO2-SnO2 (r=0.15) prepared by stearic acid method showed higher photocatalytic activity than Degussa P-25.