TiO2 nanostructures with optical and electrochemical properties have attracted much attention in the applications of sensors, water splitting and dye-sensitized solar cells, due to low cost and high stability. In order to get TiO2 with improved performance, many works have been done to optimize fabrication process and to improve electrochemical properties for applications. In this thesis, the preparation of several TiO2 nanostructure was studied with an attempt to explore applications. Main results are as follows:
Transparent membrane of titania nanotubes arrays was obtained by anodic oxidation method using sodium molybdate in electrolyte to control the density of F- in the electrolyte. The morphology and crystal structure of the nanotubes was investigated by SEM and TEM. With treatment by hydrothermal method at 120℃, a large piece of membrane of well-crystallized nanotubes array was obtained.
We used conductive Ti3SiC2 ceramics as a substrate to replace conventional Ti metal as anode. Porous TiO2 nanostructure was fabricatied by the anodization. With the elongation of annodization, the evolution of the porous structure was investigated. Based on the experimental results, we consider that the formation of porous TiO2 is the result of the corrosion of TiO2 by F-. After heat-treatment in NH3 gas, we obtained N-doped porous TiO2. Field emission measurement of the N-doped TiO2 indicated an obvious field emission property.
We used transparent membrane of TiO2 nanotubes array in dye-sensitized solar cells. It can get the photoelectricity and the open-circuit voltage (Voc) is 0.51V; Graphene and amorphous TiO2 nanotubes composites were used as active anode materials for lithium ion batteries with good cycling stability and high reversible capacity. The composite of 60% TiO2 / 40% graphene has better performance; the capacity can be above 400 mAh /g after 20 cycles.
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