陽極處理法製備二氧化鈦奈米管狀結構並應用於染料敏化太陽能電池 之研究

Growth of Titanium Oxide Nanotubes Structure employed in Dye-Sensitized Solar Cells by using anodic method

張智信(Chih-hsin Chang)

指導教授 ： 曾俊元

國立臺北科技大學/工程學院/材料科學與工程研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00339

摘要

本論文以高純度的金屬鈦(99.5 %)為陽極，金屬鉑(99.9 %)為陰極，於乙二醇(Ethylene Glycol，EG)、氟化銨(Ammonium Fluoride，NH4F)和去離子水(Deionized water，DI)混合電解液中，以恆電位之陽極處理法，製備二氧化鈦奈米管（TiO2 nanotubes）。
藉由改變不同的參數，如溫度、時間、電壓、氟化銨濃度和含水量多寡，分別觀察對於結構上的影響。在改變單一變數下，溫度上升、時間增長、電壓升高、氟化銨濃度增加均與奈米管的成長速度、長度和孔徑大小成正比。而含水量越多極化現象越明顯，相同時間下孔洞相對較大，但時間若再增加，則極化現象加劇，且氫離子與氫氧根離子易吸附於奈米管表面，而造成奈米管發生裂解，變為奈米線或奈米帶的結構。
本文成功以NH4F 0.3 wt% + DI 2 wt% + EG 98 wt%混合的電解液，在持溫5 ℃、固定電位40 V下進行恆電位陽極處理，反應時間10小時後，得到長度為12 μm，孔徑大小70 nm之二氧化鈦奈米管狀結構薄膜；由FESEM-EDX觀察發現，證實此奈米結構為中空管狀結構，且表面孔洞與管底部為極緻密結構含氧量高，而中間管狀為較鬆散的多孔性結構，含氧量較低，證實管狀結構的形成主要是由化學溶解現象造成；由X光繞射圖譜，發現此奈米結構經450 ℃熱處理6小時後，可由非結晶相結構轉變為銳鈦礦結構；且藉利用毛細現象，奈米管狀結構越長，N719染料的吸附量越大。

關鍵字

陽極處理法 ； 奈米材料 ； 二氧化鈦奈米管

並列摘要

TiO2 nanotubes are manufactured by anodization with electrolyte of mixtured of ethylene glycol (EG), ammonium fluoride (NH4F) and DI water, high purity titanium (99.5%) as anode and platinum (99.9%) as cathode.
Effect of growth parameters such as, temperature, time, voltage, concentration of ammonium fluoride and water content on the formation of titanium oxide structures were studied. It was found that, the growth rate, length and hole size of TiO2 nanotubes increase to with an increase in temperature, time, voltage and concentration of ammonium fluoride. The more water content leading to obvious polarization phenomenon results in larger hole size. However, the polarization phenomenon becomes more intense with increasing time which results in the fluorine ion and hydroxide ion adhesive to the surface of TiO2 nanotube readily causing crack of nanotubes and turns into the structure of nanowire or nanobelt.
The TiO2 nanotubes with a length of 12 μm, hole size of 70 nm are successfully obtained through the anodization with the electrolyte of the mixture of NH4F 0.3 wt% + DI 2 wt% + EG 98 wt% at constant temperature of 5 ℃,constant voltage 40V for 10 h. This nano-structure observed by FESEM-EDX is a hollow tube structure. The tubes have a porous surface but the percentage of oxygen content and density between bottom and top is higher than the middle tubes. Therefore, it is confirmed that formation of the tube structure is mainly attributed to the chemical dissolution. From the XRD diffraction pattern, the amorphous tube was crystalled into anatase phase after heat treatment at 450 ℃ for 6 h. The longer nanotubes, possess the larger adhesive of N719 dye is due to the capillarity action.

並列關鍵字

anodic ； nano-material ； nanotube ； titanium oxide

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