Ag/TiO2製備方法對於光催化活性的影響

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题名:	Ag/TiO2製備方法對於光催化活性的影響
作者:	曾卉蓁;Tseng, Hui-Jen
贡献者:	化學工程與材料工程學系
关键词:	二氧化鈦;銀摻雜;光觸媒;光還原法;含浸法;光催化降解
日期:	2019-06-24
上传时间:	2019-09-03 12:28:36 (UTC+8)
出版者:	國立中央大學
摘要:	二氧化鈦光觸媒以其優異的環境自潔能力引起相當大的關注。然而由於其能隙較大，因此半導體材料的光吸收效果及超親水性的轉化僅限於紫外光波段。然而，由於二氧化鈦具有較寬能隙，因此其在可見光區域下的活性效率低。本研究目的是研究紫外光照射下亞甲藍降解的光催化效果，並分別以光還原法和含浸法製備Ag摻雜的Evonik-Degussa的商業二氧化鈦粉末。所有樣品均通過X射線衍射和高分辨率透射電子顯微鏡表徵。光催化反應在10ppm亞甲基藍溶液中進行，其中四個9瓦 UVC光（波長為254奈米）燈管作為UV光源以及四個9瓦可見光燈管作為可見光源。以紫外光-可見分光光譜儀測量樣品的亞甲基藍降解濃度。研究發現摻雜銀增加二氧化鈦的粒徑大小。添加銀能夠產生等離子體效應。銀陽離子呈銀一價離子形式摻入二氧化鈦晶格中，使得二氧化鈦表面缺陷。在二氧化鈦晶格中銀一價離子取代鈦四價離子的位置中存在的負責增加UVC光吸收並引起光誘導電子的偏析，從而抑制電子和空穴的複合。光催化活性結果顯示以含浸法製備的樣品比光還原法製備的樣品更高的光催化活性，因為含浸法比光還原法產生更高的銀分散。在紫外和可見光照射下，銀摻雜二氧化鈦比原始二氧化鈦具有更高的光催化活性。;TiO2 based photocatalysts have acquired considerable attention due to the outstanding functions of environmental cleaning such as pollution removal. However, since TiO2 has a wide band gap, its activity under visible region has low efficiency. The main purpose of this study was to investigate the photocatalytic effectiveness of degradation of methylene blue under the ultraviolet light irradiation. Ag-doped TiO2 powders were prepared by photoreduction and impregnation methods, respectively. Commercial TiO2 from Evonik-Degussa (P-25) was used in this study. All the samples were characterized by X-ray diffraction and high resolution-transmission electron microscopy. The photocatalytic reaction was executed in a 10 ppm methylene blue solution with four pieces of 9 W UVC light (254 nm wave length) as the UV light source, and four pieces of 9 W visible light as the visible light source. The degradation sample of the methylene blue concentration was measured by a Ultraviolet-visible spectrophotometer. It was found that doping silver increased the particle size of TiO2. Adding silver can have plasmon effect. The silver cations were in form of Ag+ ions and were incorporated into TiO2 lattice, and led to defect on the surface of TiO2. Ag+ ions presented in the substitutional site of Ti4+ in TiO2 lattice are responsible for increasing UVC light absorption and causing the segregation of the photo-induced electrons so that it could suppress the recombination of electrons and holes. Photocatalytic activity results showed that the samples prepared by impregnation method had a higher photocatalytic activity than those by the photoreduction method since the impregnation method yielded a higher silver dispersion than photoreduction method. The Ag-doped TiO2 showed a higher photocatalytic activity than the pristine TiO2 under UV and visible light irradiation.
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