隨著石油能源的耗竭以及其造成全球暖化的影響，以氫能源作為一種可再生能源受到許多矚目，其中致力於光催化產氫的研究是一大潛力能源再生方法。但許多適合用於光催化產氫的半導體材料因其能隙過大，無法有效利用可見光波段進行產氫。由電漿子金屬和不同的介電層半導體材料所組成的複合奈米結構因其特別的表面電漿性質而越來越受到重視，半導體材料的光催化效率也能因而提升。
在本研究中，合成不同形狀的奈米金粒子-二氧化鈦的複合奈米粉末進行光催化產氫的研究。透過結合晶種還原法、配體交換法等技術，開發出一套能夠將相同尺寸、不同形狀之金奈米粒子附著於二氧化鈦奈米粉末上的製程。以此作為光催化產氫的催化劑。在光催化產氫的結果中，無論是模擬太陽光的情況，或是全光譜的照射下，同時擁有兩種形狀奈米金粒子之組合的產氫效率相對於只有其中一種形狀的試樣高出許多，並成功的使二氧化鈦應用於產氫上。
此外，為了更深入探討其結構的表面電漿共振特性，利用有限時域差分法對奈米金粒子-二氧化鈦的交互作用進行模擬。從模擬的結果中得知電場強度較高的地方集中在金粒子-二氧化鈦交接面上，且靠近邊緣處。亦從模擬中得知在只有奈米金粒子的情形下吸收峰的波長與尺寸形成正比，與形狀較為無關；而在金粒子-二氧化鈦的模擬中得知吸收峰值隨著形狀以及接觸面的不同有所改變。

With the depletion of petroleum energy and its detrimental impact on global warming, hydrogen energy as a renewable energy source has attracted a lot of attention. Photocatalytic hydrogen production is a promising green and renewable energy resource. However, many semiconductor materials that are suitable for photocatalytic hydrogen production cannot effectively make use of the visible light band for hydrogen production due to their large energy gap. Composite nanostructures with plasmonic materials and different dielectric layer semiconductor materials have attracted much attention due to their special surface plasmonic properties which may further enhance the photocatalytic efficiency of semiconductor materials.
In the present research, Au-TiO2 heterostructures were synthesized with different shapes of gold nanoparticles on TiO2 powders for the enhancement of photocatalytic hydrogen production. By combining the seed-mediated method, ligand-exchange method and ion exchange method, the samples with Au nanoparticles of the same size and different shapes to TiO2 nanopowders were prepared for photocatalytic hydrogen production. The results revealed that heterostructures of mixed-shape Au nanoparticles exhibit higher hydrogen production efficiency than the heterostructures with Au nanoparticles of one-shape.
To clarify the surface plasmon resonance characteristics of its structure, we used the finite time domain difference (FDTD) method to simulate the LSPR effects between Au nanoparticles and TiO2. The results showed that intense electric field is concentrated at the corners of the junction face of Au and TiO2. In addition, the absorption spectra are largely determined by the size and less so by the shape of Au nanoparticles. It is consistent with the experimental findings that the samples with mixed-shape nanoparticles absorb more intense light than that with only one shape nanoparticles.

Abstract II
摘要 III
致謝 IV
Acknowledgments V
Contents VI
Chapter 1 Introduction 1
1.1 Research Background 1
1.1.1 Hydrogen Energy 1
1.1.2 Hydrogen Production by Photocatalytic Water Splitting 3
1.2 Plasmonic Properties of Nanomaterials 5
1.2.1 Overview of Plasmonic Properties of Nanomaterials 5
1.2.2 Localized Surface Plasmon Resonance and Applications 5
1.2.3 Surface Plasmon Polaritons (SPP) and Applications 9
1.2.4 Plasmonic Materials 10
1.2.5 Mechanisms of Photocatalytic Plasmon Enhancement 11
1.3 Properties of Au and TiO2 13
1.3.1 Properties of Au 13
1.3.2 Properties of TiO2 14
1.3.3 Au/TiO2 Nanocomposites in Water Splitting 16
1.4 Motivation 17
Chapter 2 Experimental Section 18
2.1 Experimental Flowchart 18
2.2 Experimental Procedures 20
2.2.1 Preparation of Au Nanoparticles 20
2.2.2 Ligand-exchange Method for Au/TiO2 Nanocomposites 21
2.2.3 Measurements of H2 Production Efficiency with Au/TiO2 Composites 23
2.2.4 FDTD Simulation Test 24
2.3 Experimental Characterizations 28
2.3.1 Scanning Electron Microscopy (SEM) 28
2.3.2 Fourier-transform Infrared Spectroscopy (FTIR) 29
2.3.3 Transmission Electron Microscope (TEM) 30
2.3.4 Gas Chromatography (GC) 31
2.3.5 Finite-difference Time-domain Method(FDTD) 32
Chapter 3 Results and Discussion 33
3.1 Characterizations of Au/TiO2 Nanocomposites 33
3.1.1 SEM Analysis 33
3.1.2 XRD Analysis 34
3.1.2 FTIR Analysis 35
3.1.3 TEM and EDS Analysis for Au/TiO2 Nanocomposites 36
3.2 Au/TiO2 Nanocomposites for H2 Production and Investgation of LSPR Effects 37
3.2.1 Hydrogen Production Test of Au/TiO2 Nanocomposites 37
3.2.2 FDTD Simulation 41
3.2.3 Stability Test 45
Chapter 4 Summary and Conclusions 47
Chapter 5 Future Prospects 48
5.1 Shaped Pervoskite-TiO2-Au Nanocomposites for High-Efficiency Photocatalytic Hydrogen Production 48
5.2 Scalable Production of Noble Metal Nanoparticles for Hydrogen Production 50
References 51

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