| Semiconductor titanium dioxide (TiO2) nano-materials have drawn much more attention in the field of dye-sensitized solar cells, lithium batteries,anti-fog and self-cleaning and photocatalysis owning to its high chemical stability, non-toxicity, environmental friendliness, resistance to acid and alkali, wide band gap and so on. Moreover, the size and dimensionality of nano-materials have been become the key consideration in the areas of application and material preparation. The three-dimensionalTiO2 nanomaterials assembled of one-dimensional nano-structures own specific morphology and dimensionality, which has been expected to perform new superiority in dye-sensitized solar cells and photocatalysis because of its perfect combinations of the advantages of one-dimensional and three-dimensional (3D) structures. Therefore, the synthesis and applications of TiO2 nano-materials with unique geometrical morphology and dimensional size have been seeing one of the key contents in nano-materials. In this work,3D TiO2 nano-structures with different micro-structures have been prepared in different solvent system via solvothermal route, Meanwhile, the photocatalytic and photovoltaic performance of the 3D TiO2 nano-structures also be studied then. The main researches and results are as following:1.3D TiO2 nano-structures with different morphologies assembly of one-dimensional have been successfully prepared via additive-free and template-free solvothermal method in different systems of non-solvent and water (n-hexane-water, chloroform-water, cyclohexane-water) using tetrabutyl tianate and titanium tetrachloride as the precursors. The mechanism of the significance of the quality of solvents and the surface tension on the microstructure and morphology of the assembled nano-structures has been discussed in detail. It can be seen that the 3D TiO2 nano-structures with perfect sea-urchin morphology only could be synthesized in the cyclohexane-water system. Furthermore, the photocatalytic properties of 3D TiO2 nano-structures synthesized in the three different solvents have been analyzed, due to the specific dimension, the high specific surface areas and the strong light scattering ability, the 3D TiO2 samples exhibit better photocatalytic activity compared with the commercial P25, however, the photocatalytic quality of 3D sea-urchin TiO2 nano-structures is the best among them.2. In the system of cyclohexane-water, the influence of reaction temperature, reaction time, the concentration of each precursor, the volume of solvent on the crystal structure and morphology of 3D TiO2 nano-structures is discussed. The one-dimensional assembled into sea-urchin 3D TiO2 can be obtained by controlling the mass fraction of titanium tetrachloride at 50wt.%, the volume of tetrabutyl titanate at 5mL, the volume of cyclohexane at 30mL, the reaction temperature at 150℃ and the reaction time at 18h. With time as the variable quantity, the mechanism of one-dimensional nanorods assembled into 3D sea-urchin TiO2 microspheres possibly follows the process:the growth center from the aggregates of nanoparticles, the formation of nanorods from the adsorption of nanoparticles, self-assembly, growth; the effects of the above experimental parameters are discussed by then.3. The results of photoelectric analysis have indicated that the geometrical morphology of 3D TiO2 nano-structures plays an important role in the property of the TiO2 anode electrode. In the system of cyclohexane and water, the morphology of 3D TiO2 microspheres assembly of one-dimensional nanorodas can be changed by adjusting the reaction temperature. It can be observed that 3D sea-urchin TiO2 microspheres assembled by the low-dimensional nanoraods show the best optical performance, the relevant parameters of dye-sensitized solar cells which used 3D sea-urchin Tio2 microspheres as the material of anode is listed as follows, the current density (Jsc) is 20.5 mA/cm2, the open circuit voltage (Voc) is 0.98V, the fill factor (FF) is 0.43, the photoelectric conversion efficiency (PCE) is 8.04%. The main factors can be explained as following:the high specific surface area, the strong capability of light scattering, the rapid transportation of photon-generated carriers. |
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