二氧化鈦 ( TiO2 ) 在觸媒、感測器、太陽能電池、生醫材料、表面自潔等皆有廣泛的研究。不同形貌結構與表面修飾處理對於提升性質與擴展二氧化鈦應用扮演著相當重要的角色。本研究第一部分探討超臨界流體處理 ( ScCO2 fluid cleaning ) 對於一維二氧化鈦奈米管陣列 ( TiO2 nanotubes ) 表面性質影響。實驗結果顯示不同管徑二氧化鈦奈米管陣列皆從親水性轉變成疏水性。藉由XPS分析表面鍵結，發現其碳-氫鍵結 ( C-H functional groups ) 訊號明顯上升。為深入探討其機制，比較於退火後所形成銳鈦礦相 ( anatase phase ) 二氧化鈦奈米管陣列表面親疏水性。超臨界流體處理後，退火後二氧化鈦奈米管陣列表面所產生之碳-氫鍵結明顯較少，所量測之接觸角上升幅度下降。可得知二氧化碳超臨界流體對於二氧化鈦奈米管陣列表面鍵結改變具有重要影響。並藉由這樣的特性結合超臨界流體處理與紫外光線照射，使二氧化鈦奈米管陣列表面擁有良好光感測性，形成一可逆轉換浸潤性材料。
在本論文的第二部分我們以電紡絲技術製備表面親水性一維二氧化鈦奈米纖維 ( TiO2 nanofibers ) ，結合生物分子抗體 ( Antibody ) 作為介質，成功以一種無毒且簡易的方式製備出高均勻性的銀奈米粒子修飾-二氧化鈦奈米纖維 ( Ag-TiO2 ) 異質結構。根據實驗結果顯示，以抗體介質合成銀修飾二氧化鈦奈米纖維對於提升光催化活性與感測性有顯著的影響。銳鈦礦與金紅石 ( rutile ) 混和相之Ag-TiO2奈米纖維，在光催化下具有高效能的染料降解效率。並進一步證實二氧化鈦奈米纖維在適當條件下具有過氧化物酶特性 ( peroxidase-like activity ) 能間接偵測葡萄糖濃度。實驗結果顯示修飾過後Ag-TiO2奈米纖維良好的光催化與生物親和力大幅提升了葡萄糖感測靈敏度。

Titanium oxide (TiO2) has been widely applied in photocatalysts, sensors, solar cells, biomaterials, self-cleaning and so on. The surface morphology and surface chemical modification play important role in the properties of TiO2. This study employed a supercritical-CO2-fluid (ScCO2) cleaning process to modify the chemical properties of anodic TiO2 nanotubes surface. We found that ScCO2-treated TiO2 nanotubes can effectively change their surface wettability as a result of photo-oxidation of C-H functional groups formed on the TiO2 surface. In addition, the crystal structure of TiO2 nanotubes transformed from amorphous phase to anatase after annealing at 450 °C for 2 hours. The C-H functional groups of annealed TiO2 nanotubes were significantly less than amorphous TiO2 nanotubes after the ScCO2 cleaning process. We demonstrated a switchable superhydrophilicity of ScCO2-treated anodic TiO2 nanotubes with UV-light irradiation.
In the following, TiO2 nanofibers with different size and crystal structures have been synthesized by electrospinning and further decorated with silver nanoparticles through antibody-mediated synthesis. The study indicates that Ag nanoparticles are uniform deposited on TiO2 nanofibers. Ag-TiO2 nanofibers possessed superb photocatalytic activity for the degradation of Rhodamine B ( RhB ) dye. This study also demonstrates that TiO2 nanofibers possess intrinsic peroxidase-like activity in suitable condition. Ag-TiO2 nanofibers show excellent catalytic performances and good biocompatibility so that they can be used a colorimetric biosensor for glucose detection.

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