| Summary: | 碩士 國立清華大學 化學系 GH000943451 摘要 自工業革命以來，人類社會對能量需求大幅提升，工業的發展以及交通的運輸，均產生大量溫室氣體，如二氧化碳以及氮氧化合物等。這些溫室氣體不僅造成了溫室效應，也產生海水酸化問題，嚴重影響地球的生態，因此減少大氣中二氧化碳的含量是一重要的課題。本研究利用二氧化鈦奈米粒子，光催化二氧化碳還原為甲醇，並以層接層 (Layer-by-Layer) 的方式，和二氧化矽在聚酯基材上形成多層複合薄膜，以此薄膜進行光催化反應。研究中以掃描式電子顯微鏡、飛行時間式二次離子質譜儀以及接觸角量測儀，鑑定奈米多層膜的特性，研究結果指出，第一層粒子的吸附能力以及基材表面的平整度會影響整體密度，且多層膜結構中不同粒子並未獨立分層，而是有部分混雜的情形。此外奈米多層膜的親水性，會隨著鍍膜層數增加而提升，當層數達到六層時，接觸角可降低至僅有5°，表現出超親水的特性。在二氧化碳還原反應中，我們利用自行架設的光反應器暨線上分析系統，分析二氧化碳光還原的產物。實驗結果顯示，當鍍膜層數在八層以下時，鍍膜層數愈多催化效率愈好，得到甲醇的產率愈高，最高可達到9.7 µmol。 Abstract Industrial revolution resulted in increased inputs of green house gases, among which carbon dioxide (CO2) is the major contributor. Excessive emission of CO2 is considered to be the major cause for global warming and ocean acidification. This eventually has made a significant impact on global climate and ecology. Thus, reducing CO2 concentration in the atmosphere will be an important topic. In this study, we use titanium dioxide (TiO2) nanoparticles as catalyst for reducing carbon dioxide to methanol. We prepared TiO2/SiO2 thin film by layer-by-layer technique and characterized by scanning electron microscope, time of flight-secondary ion mass spectrometer and goniometer. Analysis results revealed that adsorption ability of first layer and roughness of substrate surface had an important effect on the film density. Besides, each layer was mixed with TiO2 and SiO2 nanoparticles rather than completely separated. The hydrophilicity was enhanced when increasing the number of layer; the film became superhydrophilic when coating to 6 layers. In CO2 photoreduction experiment, we used a lab-built photoreactor combined with analytical system to analyze the product of CO2 reduction. The results indicated that the photocatalytic efficiency increased with the number of layer and the yield of methanol reached maximum, 6.5 ?mol, when the layer number was 8.
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