| Summary: | 碩士 === 國立中興大學 === 材料工程學研究所 === 91 === Nano-structured titanium dioxides exhibiting their high specific surface area, excellent electronic and optical properties have many applications, including photocatalysis, dye-sensitized solar cell, superior and biocompatible applications, etc. This study employed electrochemical anodic oxidation to synthesis nano-structured titanium dioxide films on different substrates, especially on heterogeneous substrates, such as silicon wafers and polymers. It is noteworthy that the pre-deposition of titanium film is one of the requirements for heterogeneous substrates. This novel processing is clearly fit into the main stream of nanotechnology.
Anodic oxidation was performed by using linear sweep voltammetry mode at room temperature in highly alkaline electrolytes, such as KOH. Field-emission scanning electron microscopy results show that nano-network structured titanium dioxides films were successfully fabricated on Ti-coated Si wafers within several minutes with scanning cutoff voltages ranging from 3 to 85 V (scanning rate: 10 mV/s) in 1 M KOH electrolytes. The inner diameter of the nano-network rings is about 50 nm and the ring width is less than 10 nm. Raman spectroscopy results show that single anatase TiO2 phase was present with scanning cutoff voltages ranging from 20 to 85 V. The thickness of nano-network TiO2 films could reach as high as 250 nm. After annealing at 500℃, the obtained anatase phase could be fully transformed to rutile phase without breaking the nano-network structure. When H2SO4 electrolyte was used, nano-particle structured titanium dioxides films were formed with scanning cutoff voltages ranging from 10 to 60 V (scanning rate: 3 mV/s). The mean particle size is less than 10 nm and the resultant crystal structure is anatase TiO2. The thickness of nano-particle TiO2 films could reach as high as 80 nm.
This TiO2/Ti/substrates sandwiched structure possesses superior adhesion behavior and the titanium film could also prerent the substrates from being determined by the photocalytic reaction. Above all, nano-structured TiO2 could be prepared within only several minutes on many different substrates. This process has enormous potential applications.
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