本實驗室已在甲基橙之光降解中證實氧化亞銅之晶面效應，指出：氧化亞銅立方體無光催化活性；菱形十二面體具高度光催化活性；及八面體具中度光催化活性。為擴展此研究，本實驗室使用奈米金粒子修飾氧化亞銅表面；並藉由在氧化亞銅上生成半導體，例如氧化鋅、硫化鎘、硫化鋅及磷酸銀，以嘗試合成半導體-半導體之異質結構。本論文探討氧化亞銅晶體之有機分子表面修飾如何影響其能帶結構及光催化活性。

特別是對於4-乙炔基苯胺修飾之氧化亞銅立方體，使一般無活性的氧化亞銅立方體變得具有相當的光催化活性，在50分鐘內降解甲基橙至大約3 %。加入電子及電洞捕捉劑之後，甲基橙之降解受到抑制。EPR分析揭露了氫氧自由基之形成。EIS分析指出在4-乙炔基苯胺修飾後之電荷轉移電阻顯著的降低。Mott-Schottky分析顯示了價帶及導帶的位置有顯著的改變，解釋了氧化亞銅立方體之光催化活性。

We have already demonstrated the facet-dependent performance of Cu2O nanocrystals in the photocatalytic degradation of methyl orange, indicating that Cu2O cubes are photocatalytically inactive, while rhombic dodecahedra are highly photocatalytically active, and octahedra are moderately active. We extended our investigation to decorate Cu2O surfaces with gold nanoparticles and try to synthesize semiconductor‒semiconductor heterojunctions by growing semiconductor such as ZnS, CdS, ZnS, and Ag3PO4 on Cu2O crystals. This thesis explores how surface organic molecule modification of Cu2O crystals affect their band structures and photocatalytic activity.

Specifically for 4-ethynylaniline-modified Cu2O cubes, the normally inactive Cu2O cubes become fairly photocatalytically active, degrading methyl orange to almost 3 % in 50 min. Degradation of methyl orange was suppressed upon adding electron and hole scavengers. EPR analysis reveals the formation of hydroxyl radicals. EIS analysis indicates significantly reduced charge transfer resistance upon 4-ethynylaniline modification. Mott-Schottky analysis shows greatly tuned valance and conduction band positions, accounting for the observed photocatalytic activity of Cu2O cubes.

論文摘要 i
ABSTRACT ii
TABLE OF CONTENTS iii
LIST OF FIGURE v
LIST OF SCHEME xii
LIST OF TABLES xiii
1. Introduction 1
1.1 Cuprous oxide with specific facets 1
1.2 Facet-dependent electrical conductivity properties of Cu2O and Ag2O crystals 2
1.3 Facet-dependent photocatalytic properties of Cu2O and Ag2O crystals 7
2. Demonstration of photocatalytic activities of Cu2Opolyhedra after surface-functionalization with 4-ethynylaniline 10
3. Experimental Section 13
3.1 Chemicals 13
3.2 Synthesis of Cu2O nanoparticles 13
3.3 Aryl alkyne-functionalized Cu2O crystals 16
3.4 Facet-dependent photocatalytic activities of aryl alkyne-functionalized Cu2O polyhedra 17
3.5 Electron paramagnetic resonance analysis 19
3.6 Electrochemical measurements 21
3.7 Instrumentation 22
4. Results and Discussion 23
5. Conclusion 45
6. References 46

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