近年來，異質結構，特別是Ⅱ型異質結構，因其在光催化水分解產氫的潛力，得到學界與業界越來越多的注意。本研究製備Cu2O/CdS的異質結構，以形成Ⅱ型異質結構，更加有效率分離電子與電洞進而加強光催化效率。同時通過以鉑奈米顆粒修飾CdS/Cu2O異質結構，進一步提升光催化效率。
藉由水熱高壓法合成了CdS奈米圓形顆粒，而Cu2O則採用化學溶液法制備。我們研究了不同摻雜比例的CdS/Cu2O異質結構，評估它們在光催化水裂解產氫的能力。結果顯示，在CdS/Cu2O異質結構中加入5 wt.%的Cu2O比單獨使用純CdS奈米顆粒增 550 %的光催化效率。
我們進而運用化學合成法生成鉑奈米顆粒修飾CdS/Cu2O(5 wt.%)異質結構，鉑作為共觸媒使電子更容易跨過固液介面，電子便會更快的與水溶液中的氫離子結合，使有鉑修飾的異質結構比沒有鉑修飾地增加了270 %的光催化效率。
本研究合成出鉑修飾在Cu2O/CdS的異質結構，透過異質結構使傳輸載子分離效率增強和共觸媒鉑提升載子傳輸的速度，提升了原材料的光催化效率。研究結果驗證異質結構和共觸媒在光水解產氫中飾演舉足輕重的角色。

Heterostructures have gained significant attention recently due to their increasing importance and relevance to combat global warming. Type II heterojunctions has been of particular interest due to their potential for enhancing hydrogen production through water splitting. The current study focused on synthesizing CdS/Cu2O heterostructures to form type II heterojunctions, enabling efficient charge separation and significantly improving hydrogen production efficiency. We also enhanced the photocatalytic performance further by decorating Pt onto the CdS/Cu2O heterostructures.
CdS nanoparticles were prepared through a hydrothermal method, while Cu2O was synthesized using a chemical synthesis approach to synthesize the heterostructures. We systematically investigated different weight percentages of CdS/Cu2O heterostructures to evaluate their performance in hydrogen production during water splitting. Our results for five wt.% Cu2O in the CdS/Cu2O heterostructures showed higher photocatalytic efficiency than pure CdS nanoparticles alone.
We employed a chemical synthesis method to optimize hydrogen production further by decorating Pt onto the five wt.% Cu2O of the CdS/Cu2O heterostructures. The decorated structures led to the highest yield in hydrogen production, which can be attributed to the effectiveness of Pt as a cocatalyst.
Our study highlights the significance of CdS/Cu2O heterostructures in improving hydrogen production efficiency through water splitting. We enhanced photocatalytic performance by utilizing Pt as a cocatalyst on the CdS/Cu2O heterostructures. These findings contribute to understanding heterostructure-based photocatalysis and offer potential avenues for developing efficient systems for renewable hydrogen production.

Contents
Abstract i
摘要 ii
致謝 iii
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 Nanomaterials 7
1.2.1 Overview 7
1.2.2 Classification of Nanomaterials 8
1.2.3 Synthesis Methods of Nanomaterials 10
1.3 Heterostructure 12
1.3.1 Overview 12
1.4 Cocatalyst 14
1.4.1 Overview 14
1.4.2 Volcano plot 15
1.5 Material Selection 17
1.5.1 Properties of CdS 17
1.5.2 Properties of Cu2O 18
1.5.3 Properties of Pt 20
1.5.4 Properties of Pt Decorated CdS/Cu2O 22
1.6 Motivation 23
Chapter 2 Experimental Section 25
2.1 Experimental Equipments and Instruments 25
2.1.1 X-ray Diffraction (XRD) 25
2.1.2 Scanning Electron Microscope (SEM) 26
2.1.3 Transmission Electron Microscope (TEM) 27
2.1.4 Ultraviolet-Visible Spectrometer (UV-Vis) 29
2.1.5 Gas Chromatography (GC) System 30
2.1.6 Photoluminescence (PL) Spectrometer 32
2.1.7 X-ray Photoelectron Spectroscope (XPS) 33
2.2 Experimental Procedures 35
2.2.1 Synthesis of CdS Nanoparticles 36
2.2.2 Synthesis of Cu2O 37
2.2.3 Synthesis of CdS/Cu2O Heterostructures 39
2.2.4 Synthesis of Pt Decorated CdS/Cu2O Heterostructure 40
2.2.5 Hydrogen Production Efficiency Measurement 40
Chapter 3 Results and Discussion 42
3.1 Characteristics of CdS NPs 42
3.1.1 SEM Analysis 42
3.1.2 XRD Analysis 43
3.1.3 UV-Vis Absorbance Spectrum 45
3.1.4 TEM Observation and Analysis 47
3.2 Characteristics of Cu2O 50
3.2.1 SEM Analysis 50
3.2.2 XRD Analysis 51
3.2.3 UV-Vis Absorbance Analysis 53
3.2.4 TEM Observation and Analysis 55
3.3 Characteristics of Pt Decorated CdS/Cu2O Heterostructure 56
3.3.1 XRD Spectrum of CdS/Cu2O 56
3.3.2 SEM Image of Pt Decorated CdS/Cu2O Heterostructure 57
3.3.3 H2 Production Measured by GC System 58
3.3.4 Effects of Different Cu2O Weight Percentages 58
3.3.5 Effects of Different Pt Weight Percentages 60
3.3.6 PL Spectrum 62
3.3.7 XPS Analysis 64
3.3.8 Stability Test 65
Chapter 4 Summary and Conclusions 68
Chapter 5 Future Prospects 70
5.1 Photocatalysis of Pt Decorated CdS/Cu2O Heterostructure Based on Various Shapes of Cu2O 70
5.2 Photocatalytic Enhancement of H2 Production by Water Splitting with CdS Thin Film Produced by Atomic Layer Deposition Combined with the Cu2O 72
References 73

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