臺灣博碩士論文加值系統

近年來，由電漿子金屬和不同的半導體材料所組成的複合奈米結構因特殊的局部表面電漿共振效應在光催化的領域越來越受到重視。在主要的光催化材料中往往引入電漿子金屬產生電漿子強化光吸收以及電漿子敏化現象使光催化的效率有效提升。
本研究除了探討電漿子對光催化產氫的影響同時也改變基板表面結構。我們將水熱法合成的硫化鎘奈米顆粒分布在蝕刻過後表面有金字塔結構的矽基板上，最後使用電子束蒸鍍系統鍍上不同厚度的金形成Au/CdS/Si的三層結構來進行光催化水分解產氫的研究。結果顯示表面有金字塔結構的基板確實會因為表面積增加而在重量相同的光催化材料下形成較高的光催化效率。
在硫化鎘上鍍不同厚度(10、20、30奈米)的金作為電漿子材料後，結果顯示鍍了20奈米金膜且在金字塔結構的基版上的產氫效果最好。而厚度最厚的金膜對整體的光催化效果來說並不是最好，因為光催化材料被過厚的金遮住而無法有效吸收光，無法發揮硫化鎘的最佳光催化效果，但這反而提升了材料的耐用度，在耐用性測試的結果顯示此組數據在貯存光催化系統七天後的光催化效果下降得最少。

In recent years, the heterostructures composed of plasmonic metal and semiconductors have attracted attention due to the localized surface plasmonic resonance effect, which can enhance the catalytic effect owing to plasmonic sensitization and plasmon-enhanced light absorption
In the present work, the influences of both plasmonics and structures of the substrate on photocatalysis are addressed. The CdS nanoparticles were synthesized by a hydrothermal method and dispersed on the etched pyramidal surface of the Si substrate. Then Au/CdS/Si structures with different thicknesses of Au deposited by electron beam evaporation were investigated for hydrogen production from water splitting. The increase in surface area with pyramidal Si structure was found to lead to a higher efficiency of photocatalysis than the flat Si surfaces.
Additionally, among the samples with different thicknesses of Au layer (10, 20, and 30 nm) deposited on CdS, the one with a 20 nm Au layer lead to the best yield in hydrogen production instead of the one with the thickest Au layer. The result can be attributed to the decrease in light absorption. As the thickness of the Au layer increases, the layer will prevent light from reaching the semiconductors below the layer, resulting in lower photocatalytic efficiency. However, the photocatalytic ability of samples with the thickest Au layer was the most durable after storing for 7 days, indicating the best protection of the underlying CdS layer.

Abstract I
摘要 II
致謝 III
Contents IV
Chapter 1 Introduction 6
1.1 Research Background 6
1.1.1 Hydrogen Energy 6
1.1.2 Hydrogen Production Route 7
1.1.3 Hydrogen Production by Photocatalytic Water Splitting 10
1.2 Nanomaterials 13
1.2.1 Overview 13
1.2.2 Classification of Nanomaterials 14
1.2.3 Nanomaterials Synthesis Methods 16
1.3 Plasmons 18
1.3.1 Overview 18
1.3.2 Localized Surface Plasmon Resonance (LSPR) 19
1.3.3 Surface Plasmon Polariton (SPP) 21
1.3.4 Photocatalytic Plasmon Enhancement 22
1.3.5 Plasmonic Materials 24
1.4 Material Selection 26
1.4.1 Properties of CdS 26
1.4.2 Properties of Au 27
1.4.3 Properties of Au/CdS Composites 28
1.4.4 Pyramidal Si Substrate 30
1.5 Motivation 31
Chapter 2 Experimental Section 33
2.1 Experimental Procedures 33
2.1.1 Synthesis of CdS Nanoparticles 34
2.1.2 Preparation of Pyramidal Si Structure 35
2.1.3 Deposition of Au/CdS Nanocomposites 37
2.1.4 Hydrogen Production Efficiency Measurement 38
2.1.5 Material Analysis Methods 39
2.2 Experimental Characterizations 40
2.2.1 Scanning Electron Microscopy (SEM) 40
2.2.2 Energy-Dispersive X-ray Spectroscopy (EDS) 41
2.2.3 X-ray Diffraction (XRD) 42
2.2.4 Ultraviolet–Visible Spectroscopy (UV-Vis) 43
2.2.5 Transmission Electron Microscope (TEM) 44
2.2.6 Gas Chromatography (GC) 45
2.2.7 Focused Ion Beam (FIB) 46
2.2.8 Electron Beam Evaporation System (E-gun) 46
Chapter 3 Results and Discussion 47
3.1 Characteristics of CdS NPs 47
3.1.1 SEM Observation 47
3.1.2 XRD Analysis 48
3.1.3 TEM Observation and Analysis 50
3.1.4 UV-Vis Absorbance Spectrum 51
3.2 Morphology of Pyramidal Si Substrate 52
3.3 Characteristics of Au/CdS/Si Structure 53
3.4 H2 Production Measured by GC System 55
3.4.1 Effects of Different Structures of Substrate 55
3.4.2 Effect of LSPR with Different Thickness of Au 57
3.4.3 Combination of Substrate Structure and LSPR Effect 59
3.4.4 Durability Test 61
Chapter 4 Summary and Conclusions 62
Chapter 5 Future Prospects 63
5.1 Photocatalysis of Pyramidal Composite Films Based on Plasmon-Enhanced CdS NPs 63
5.2 Plasmonic Enhancement of H2 Production by Water Splitting with CdS Nanowires Protected by Metallic TiN Overlayers on the Pyramidal Si Substrate 65
Appendix 66
Calculation of the Surface Area of CdS NPs Coated Pyramidal Si Substrate 66
References 68

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