二氧化鈦奈米結構具備無毒性、物化性質穩定，以及擁有高比表面積的特性，使得科學家致力於以簡單步驟及低成本的合成技術來製備二氧化鈦奈米結構。本研究提出以傳統的水熱法結合晶種層觀念，研究在晶種層及透明導電玻璃上製備二氧化鈦一維奈米結構，並改變製程參數，分析其特性及釐清成長機制。
本研究將Ti(OBu)4含鈦前驅物置於鹽酸水溶液中，以晶種層及透明導電玻璃作為基板，經水熱法在基板上形成二氧化鈦奈米棒陣列。研究結果得知經水熱法合成的二氧化鈦奈米棒為具有結晶性良好之金紅石相，而且每支奈米棒都是單晶結構，不需額外的退火處理。藉由晶種層添加PVP量，可以控制奈米棒密度，進而影響其奈米結構外貌型態。以透明導電玻璃作為基板，改變鹽酸水溶液中的前驅物濃度，在固定時間下，分別得到20nm的TiO2薄膜、420nm或1.5μm的TiO2奈米棒陣列及3.5μm的TiO2厚膜。
選用0.5 ml Ti(OBu)4添加入30 ml 的鹽酸水溶液中，改變反應時間及反應溫度等參數，可控制奈米棒的長度與直徑，發現最佳的參數是8小時的水熱法合成，溫度在150℃， 得到長度與直徑都較為均勻且較為獨立站立的TiO2奈米棒陣列，長度平均約為1.6μm，直徑約為 110 nm。以8小時作一次循環，分多次成長奈米棒陣列，奈米棒長度及直徑分別由1.6μm 、110 nm增加到3.5μm、378 nm，但TiO2奈米棒表面會相互接觸，不利於高比表面積特性。

Recently, one-dimensional structures, especially nanorod/wire/tube arrays, have attracted much attention owing to their excellent properties because of their large specific surface area. With the advantages of non-toxicity and chemical stability, TiO2-based nanoarchitectures have been focused for the application in the development of photo-catalyst and photoelectrochemical cells. To date, a number of approaches have been reported to fabricate TiO2 nanorod/wire/tube arrays. Hydrothermal synthesis of TiO2 nanorod arrays is a promising approach due to its ease of processing, fast reaction rate and low cost. Therefore, we combine the hydrothermal process with the seed layer concept to fabricate nanorod arrays of TiO2 on the seed layer and TCO/glass. The effect of experimental parameters on the growth characteristics and mechanisms of nanorods is evaluated.
In this research, a facile hydrothermal process using Ti(OBu)4 as the precursor is developed for the first time to grow oriented single-crystalline rutile TiO2 nanorod arrays on seed layer and TCO/glass substrates. The effect of PVP added to sol-derived seed layer is found to control the density of nanorods and affects the morphologies of nanorod arrays. Tuning the concentration of initial precursor in HCl solution, different types of TiO2 structures including 20 nm TiO2 thin films, 420 nm~1.5 μm TiO2 nanorod and 3.5 μm TiO2 thick films are obtained on FTO/glass.
The growth parameters including the growth time, the growth temperature and the initial precursor concentration could be selectively chosen to prepare TiO2 nanorod arrays with desired lengths and densities on FTO/glass substrate. It is found that free-standing TiO2 nanorod arrays are obtained at 150℃ for 8 hours. The average length and diameter of TiO2 nanorods are 1.6μm and 110 nm, respectively. We chose 8 hours as a cycle of growth time. After 1~3 cycle times of growth reactions, the length and diameter of TiO2 nanorods increase from 1.6 μm and 110 nm to 3.5 μm and 378 nm, respectively.

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