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    Title: 藉由與銀複合來提升ZnO的光催化能力
    Other Titles: Improving photocatalytic ability of ZnO by coupling with Ag
    Authors: 錢東緯;Qian, Dong-Wei
    Contributors: 淡江大學化學工程與材料工程學系碩士班
    余宣賦;Yu, Hsuan-Fu
    Keywords: ZnO;多元醇法;光化學還原法;光觸媒;光催化能力;Zinc Oxide;Polyol process;Photochemcial reduction;photocatalyst;Photocatalysis
    Date: 2012
    Issue Date: 2013-04-13 11:50:45 (UTC+8)
    Abstract: 本實驗結合多元醇法與光化學還原法來製備Ag/ZnO複合型光觸媒粉體。研究過程中,觀察和探討不同硝酸銀添加量與粉體煆燒溫度對所製得Ag/ZnO複合型光觸媒粉體性質及光催化能力的影響,並與市售TiO2粉體Degussa-P25的性質與光催化能力做比較。第一部分實驗中,主要以多元醇法來製備ZnO奈米粉體。過程中有系統的探討煆燒溫度的變化對其晶粒尺寸、比表面積、顯微結構及光催化能力的影響。隨著煆燒溫度的提升晶粒尺寸逐漸成長變大,但其比表面積則隨著溫度的提升而下降,粒子團聚也愈趨嚴重。在對亞甲基藍的紫外光催化降解測試中發現500oC的ZnO擁有最佳的光催化能力且其催化性能優於Degussa-P25。第二部分實驗中,則利用光化學還原法將金屬銀負載在先前製備出的ZnO奈米粉體上,藉由金屬銀的複合來延緩ZnO受光激發之電子與電洞的再結合速率以達到提升光催化能力的效果。光化學還原法將金屬銀負載在ZnO粉體上並不會影響ZnO
    既有的晶粒尺寸及其顯微結構,且ZnO煆燒溫度的提升會促使金屬銀負載量的增加。600oC的ZnO負載莫耳比0.045的金屬銀其比表面積、晶粒尺寸與負載金屬銀的量三者達到最佳組合,此時的Ag/ZnO在對亞甲基藍的紫外光催化降解測試中所對應單位光觸媒質量的反應速率常數值(km)高達1.93m3/(kg‧min),為P25之km值(= 0.39 m3/(kg‧min))的4.9倍。
    The ZnO and Ag-coupled ZnO (Ag/ZnO) photocatalytic particles were synthesized using a polyol process and/or a photochemical reduction technique. Effects of Ag contents and calcination temperature on characteristics and photocatalytic abilities of the ZnO and Ag/ZnO particles were investigated using thermal analysis, x-ray diffraction, infrared spectroscopy, diffusion-reflectance spectroscopy, BET specific surface area measurement, scanning electronic microscopy, transmission electronic microscopy and photocatalytic reaction test system. The properties and photocatalytic abilities of the obtained ZnO and Ag/ZnO particles were also compared with those of a commercial photocatalyst TiO2 (P25, Degussa, Germany). The ZnO powders were prepared using the polyol method, followed by calcining at different temperatures. While increasing the calcination temperature increased the average crystallite sizes and the degree of agglomeration of the ZnO particles, the specific surface area decreased with increasing the calcination temperature. By photocatalytically decomposing the methylene blue in water under the irradiation of 365-nm ultraviolet light, it was found that the ZnO calcined at 500oC exhibited better photocatalytic performance than the ZnO calcined at other temperatures and the P25. The Ag/ZnO particles were prepared by photochemically reducing Ag+ to metallic Ag on the surface of the calcined ZnO particles. Ag loaded on the surface of ZnO particles can trap the light-excited electrons from the ZnO and retard the electron-electron hole recombination rate, which should result in enhancement of photocatalytic abilities of the ZnO. It is found that the ZnO calcined at higher temperature can have more Ag nanoparticles loaded on the surface of ZnO particles. Regardless the calcination temperature used, the Ag/ZnO particles possessed better photocatalytic abilities than the ZnO particles and the P25. For photocatalytically decomposing the methylene blue in water under 365-nm ultraviolet light irradiation, the Ag/ZnO prepared using the ZnO calcined at 600oC and a Ag/ZnO molar ratio of 0.045 had a reaction rate constant (based on the mass of the photocatalyst used) km = 1.93m3/(kg‧min), which was about 4.9 times of that of the Degussa-P25 (km = 0.39 m3/(kg‧min)).
    Appears in Collections:[化學工程與材料工程學系暨研究所] 學位論文

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