臺灣博碩士論文加值系統

在過去的研究中，多晶結構二氧化鈦奈米纖維材料常被用於光電化學轉換效應(光催化)生物相容性相關研究。憑藉多功能性和低成本的優勢，「靜電紡絲技術」製成方式已被廣泛應用及探討在多晶結構奈米纖維的研究上，例如在組織工程、薄膜、太陽能電池以及化學和生物抑菌機制研究。其中，本研究最關注在生物相容的細胞成長及生物抑菌機制研究上。然而，大部分應用於此類光催化研究的n型金屬氧化物半導體如單晶結構二氧化鈦材料，多只應用於紫外光(UV光) (波長小於400 nm)的光催化研究。但本實驗利用擁有豐富缺陷性質的多晶結構的二氧化鈦奈米纖維，造成電子傳遞中受能帶深度、缺陷能階等因素影響，而又多波段可見光(波長橫跨約400 ~ 550 nm)至紫外光的光電轉換性質。但因為其材料結構本生多缺陷特性，使此技術製成之材料有高電阻、低導電度特性。故藉由氫電漿轟擊處理之方式，在適當氫電漿瓦數的轟擊下，可以調變晶粒間的能障、表面位能及與外接氣體環境立即接觸氧空缺懸擺鍵。在此類處理後，多晶結構奈米纖維也對低能量(常波長的光源，波長範圍介在620~730 nm間)的光源有反應。

延續第一階段研究，利用靜電紡絲技術製成的由奈米晶粒組成奈米纖維，擁有零維材料的高比表面積特性及一維材料較高傳輸特性的性質兩大優勢，使其可以有利用應用於生物抑菌實驗研究。使用上階段的氫電漿處理，也增加可以在生物抑菌研究上反應的氫氧自由基，亦增加其光電轉換催化效益。利用此研究關注的缺陷工程及表面工程處理，此研究顯示製成調變出可以高度運用於生物相關實驗之多晶結構二氧化鈦奈米纖維材料。

Light to electric conversion photochemical effect can be achieved by using biocompatible material, polycrystalline titanium dioxide nanofibers (poly-TiO2 NFs). With versatility and low cost advantages, electrospinning process had been explored recently as means for preparing a wide variety of polycrystalline nanofiber materials for potential applications.

Cell division and antibacterial issues were widely explored in recent research. However, as a large bandgap n type semiconductor, single crystalline TiO2 materials has the attribute of responding to UV light (400 nm). Due to the defect-rich structure, poly-TiO2 NFs can respond not only to UV light but also to visible light (wavelength between 400~550 nm). The photochemical effect can be significantly enhanced by using specific power hydrogen plasma treatment because plasma treatment can tune the barrier height between grains, surface potential and defect level. After such treatment, the soft energy light (long wavelength light, such as the red light (region wavelength between 620~730 nm)) can also be used in bio research (such as stimulating the cell growth or antibacterial growth).

Recently, there are considerable interests in electrospun TiO2 NFs as antibacterial agents owing to their large grain to grain surface and the formation of reactive hydroxyl radicals (which can react with bacteria, cell membranes, and cellular proteins, leading to cell death). However, the photocatalytic effects of TiO2 NFs are relatively low due to the rich defect states. With H2 plasma treatment passivation, the surface potential of poly-TiO2 NFs was smoothened for electrons to transport. Consequently, the H2 plasma treated TiO2 NFs remained showed greater numbers of hydroxyl radicals and significantly enhanced visible light photocatalytic antibacterial activity. Based on these defect and interface engineering, poly-TiO2 NFs with hydrogen plasma treatment is a promising candidate for biological application.

致謝................................................................I
Abstract..........................................................III
摘要................................................................V
Table of Contents.................................................VII
List of Figures....................................................XI
List of Tables.....................................................XV
List of Abbreviations and Acronyms................................XVI
Chapter 1 Introduction..............................................1
1.1 Motivation......................................................1
1.2 Nanomaterials and Nanostructure Technology......................3
1.2.1 One Dimensional Nanostructures................................3
1.3 One-Dimensional Metal-Oxide Semiconductor Nanostructure
Applications........................................................4
1.3.1 Photoelectrical Effect Applications
(Photocatalytic/Antibacterial Agent/ Photodetector).................4
1.3.2 Various Nano-surface Structure Gas Sensors....................7
1.3.3 Biomaterials Application......................................8
1.4 Titanium Dioxide (TiO2) (Brookite, Anatase, Rutile).............8
1.5 Crystalline Structure of Material..............................11
1.5.1 Single Crystalline Structure.................................11
1.5.2 Polycrystalline Structure....................................12
1.5.3 Amorphous Crystalline Structure..............................12
1.6 Surface Modification of One-Dimensional Metal Oxide Nanostructure/ Electric Conductive Transportation..................13
1.6.1 Polymer – Metal Oxide Nanostructure..........................13
1.6.2 Semiconductor – Metal Oxide Nanostructure....................14
1.6.3 Metallic – Metal Oxide Nanostructure.........................15
1.6.4 Non-metal –Metal Oxide Nanostructure.........................16
1.7 Metal-Semiconductor Contact (MS contact) Photodetector Device..18
1.7.1 Ohmic Contact................................................20
1.7.2 Schottky Contact.............................................21
1.7.3 Metal-Semiconductor-Metal Contact Photodetector..............23
Chapter 2 Experimental Procedures..................................25
2.1 Material Preparation and Device Fabrication....................25
2.1.1 Fabrication Process of Polycrystalline Metal-oxide Nanostructures.....................................................25
2.1.2 Fabrication of TiO2 NFs Photoelectrical Measurement Device...26
2.1.3 Tunable Hydrogen Plasma Treatment of TiO2 NFs................27
2.1.4 Photoelectrical Properties Measurement Procedures............28
2.1.5 Photocatalytic (Photochemical) Antibacterial Experiment......29
2.2 Experimental Systems and Procedures............................30
2.2.1 Electrospinning Nanomaterial Fabrication Instruments.........30
2.2.2 Hydrogen Plasma Bombardment System...........................32
2.2.3 Semiconductor Electrical Measurement Instruments.............33
2.3 Material Analysis Experimental Systems.........................34
2.3.1 Scanning Electron Microscope (SEM)...........................34
2.3.2 Transmission Electron Microscope (TEM).......................35
2.3.3 Energy Dispersive Spectrometry (EDS).........................36
2.3.4 X-ray Diffraction (XRD) Analysis.............................37
2.3.5 UV-Vis Spectroscopy..........................................37
2.3.6 Photoluminescence (PL).......................................38
2.3.7 X-ray Photoelectron Spectroscopy (XPS).......................39
Chapter 3 Results and Discussion...................................40
3.1 Polycrystalline TiO2 NFs Annealed at Different Temperature.....40
3.1.1 Analysis of Material Surface Structure and Characteristics of the TiO2 NFs.......................................................40
3.1.1.1 SEM Observation............................................40
3.1.1.2 EDS Analysis...............................................41
3.1.1.3 XRD Analysis...............................................42
3.1.1.4 TEM Observation............................................43
3.1.1.5 UV-Vis Light Absorbance Spectrum...........................45
3.1.2 Photoelectrical Property Measurement of Polycrystalline Not-Woven Like TiO2 Nanofiber Photodetector............................46
3.1.2.1 Metal-Semiconductor-Metal Device Structure.................46
3.1.2.2 Electrical Properties of TiO2 NFs Annealed at Different Temperatures.......................................................47
3.1.2.3 Optical Properties of TiO2 NFs Annealed at Different Temperatures.......................................................49
3.2 Photoelectrical Property Enhancement of Polycrystalline TiO2 NFs by Hydrogen Plasma Treatment.......................................51
3.2.1 Measurement of Photoelectrical Properties of Hydrogen Plasma Treated TiO2 NFs Photodetector.....................................52
3.2.1.1 Electrical Properties and Physical Mechanism...............52
3.2.1.2 Photoelectrical Properties.................................55
3.2.2 Analysis of Oxygen Vacancy Variation by Hydrogen Plasma Treatment..........................................................60
3.2.2.1 Photoluminescence (PL) Analysis............................60
3.2.2.2 X-ray Photoelectron Spectroscopy (XPS) Analysis............61
3.3 TiO2 NFs Photochemical Bio-agent...............................63
3.3.1 Biocompatibility of Polycrystalline TiO2 NFs.................63
3.3.2 Antibacterial Activity of TiO2 Nanofiber.....................64
Chapter 4 Summary and Conclusions..................................68
Chapter 5 Future Prospects.........................................69
5.1 Bio-dressing Applications......................................69
5.2 Gas Sensor: Tuning Amount of Reactive Oxide Species in TiO2 NFs................................................................69
References.........................................................71