本研究分為兩部份，在第一部份，我們以噴霧熱裂解法製作中空二氧化鈰球，並利用溶膠凝膠法將二氧化鈦披覆在中空二氧化鈰球表面，所合成的核殼結構，以X光繞射儀、穿透式電子顯微鏡、X光吸收光譜分別進行結構、形貌及電子結構之分析；以紫外光-可見光光譜及光激螢光光譜探討核殼結構的光學性質；光觸媒效果則是經由與10-5 M的亞甲基藍水溶液混合後，分別利用紫外光和可見光進行照射測試。實驗結果顯示，此製程可成功將二氧化鈦披覆在二氧化鈰中空球上，殼層厚度可經由改變二氧化鈦前驅物濃度達到控制。形成中空CeO2@TiO2核殼結構後，CeO2中的Ce3+ 含量上升，TiO2中的Ti3+含量則下降，推測原因為CeO2與TiO2間發生電荷轉移現象。在光學特性方面，與未形成核殼結構的TiO2相比，中空CeO2@TiO2核殼結構的吸收範圍較大，且光電子電洞對壽命較長。隨著TiO2殼層厚度的增加，紫外光照射下的光觸媒效果越好；但以可見光照射時，表面的TiO2殼層太厚將會影響入射光能量，導致光催化效果變差。在第二部分，我們利用退火將CeO2球表面進行改質，以促進CeO2與TiO2間的交互作用。經由比較不同的退火氣氛，包括氧化及還原氣氛，發現CeO2與TiO2間的電荷轉移現象確實可經由調整CeO2球表面狀態而增強，進一步提升樣品之光學性能。

This study is divided into two parts. In the first part, we made hollow ceria spheres by spray pyrolysis, and coated the surface of the hollow spheres with titanium dioxide by the sol-gel method. Crystallization, morphology and electronic structure was investigated by using X-ray diffractometer, transmission electron microscope, and X-ray absorption spectroscopy. Optical properties of core-shell structure was studied by ultraviolet-visible light spectrum and photo-induced fluorescence spectrum. The photocatalyst property is determined by mixing with 10-5 M Methylene blue (MB) solution, and then irradiated with ultraviolet light and visible light. It is demonstrated that hollow CeO2@TiO2 core-shell structure was successfully synthesized. The shell thickness can be controlled by changing the concentration of the titanium dioxide precursor. After the formation of core-shell structure, Ce3+ concentration in CeO2 increases, while the Ti3+ concentration in TiO2 decreases, which was attributed to the charge transfer between CeO2 and TiO2. In addition, the hollow CeO2@TiO2 core-shell structure has a wide absorption range and a long lifetime for photoelectron holes. The photocatalyst performance was enhanced with increasing the TiO2 shell thickness. In the second part, to promote the interaction between CeO2 and TiO2, the surface of CeO2 spheres was modified by tuning the annealing atmospheres, including oxidation and reduction atmospheres. It is found that the degree of charge transfer between CeO2 and TiO2 was enhanced by adjusting the surface state of CeO2 spheres, which result in the improvement of the optical properties.

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