Preparation of TiO2 and SiO2/TiO2 thin film, and its application on photocatalytic degradation of methylene blue

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Title:	Preparation of TiO2 and SiO2/TiO2 thin film, and its application on photocatalytic degradation of methylene blue
Authors:	蕭晴雪;Moongraksathum,Benjawan
Contributors:	化學工程與材料工程學系
Keywords:	二氧化矽/二氧化鈦薄膜;溶膠凝膠法;光觸媒降解;SiO2/TiO2 film;peroxo sol-gel method;photocatalytic degradation
Date:	2013-07-01
Issue Date:	2013-08-22 11:40:23 (UTC+8)
Publisher:	國立中央大學
Abstract:	目前對於二氧化鈦－二氧化矽這類新型材料有著極大的興趣。本研究著重在以過氧化溶膠凝膠法製備中性二氧化矽/二氧化鈦溶膠，其不同二氧化矽/二氧化鈦重量比為3/1 與5/1 (分別表示為ST(3) 和ST(5) )，另外，也致力於研究以含浸法(Dip-coating)製備ST 薄膜，將其放入亞甲基藍水溶液進行光催化降解。結果發現，由於二氧化矽的存在，光穿透率增加，塗佈ST(5)薄膜之玻璃與未塗佈之玻璃基材相比，其光穿透率增加了4%，然而，塗佈二氧化鈦之玻璃則減少了5% 左右。在研究鈉由玻璃基材遷移至薄膜層上的二氧化矽遷移屏障效果之前，薄膜先經過500 度C 熱處理1 小時。多層塗佈的二氧化矽－二氧化鈦薄膜也製備出作為比較。可以觀察到ST(5) 薄膜上方有0.04 At% 的少量鈉存在，而在多層塗層中鈉含量高達6.57 At%，但還是少於僅塗佈二氧化鈦之薄膜。於光催化降解亞甲基藍水溶液的反應中，基於相同數量的鈦，存在二氧化矽的薄膜可以增加光催化活性，其?燒與未?燒之ST(5) 薄膜速率常數分別為3×10-3 min-1 和 1.518×10-3 min-1 (於 UVC (254 nm)下)。此外，ST(5) 薄膜的光催化反應於UVA(365nm)燈管照射下也有活性。因此，此方法可以作為替代的方式來生產具有高光穿透率的薄膜，其塗佈於玻璃上可以具有光穿透率，同時保持良好的光催化活性。 At present titania-silica (TiO2-SiO2) has received a great interest as a novel class of materials. This study aims to investigate the synthesis of SiO2/TiO2 neutral sol at various SiO2/TiO2 weight ratios of 3/1 and 5/1 (denoted as ST(3) and ST(5), respectively) by peroxo sol-gel method, and also study on the photocatalytic degradation of methylene blue in water of ST films prepared by dip-coating technique. It was found that the transmittance increased along with the presence of silicon dioxide and could enhance the light transmittance up to 4% in case of ST(5) film when compared to the bare glass substrate, whereas the TiO2 film decreased at least 5% of transmittance. Prior to study the effect of the SiO2 migration barrier on sodium migration from substrate into the film layer, the films were treated at 500 oC for 1 hour. The multilayer coating of SiO2 and TiO2 (S/T) was also prepared for comparison. It could observe that ST(5) film could be detected a small amount of 0.04 At.% sodium content at the surface, whereas the multilayer coating showed the content of sodium up to 6.57 At.% but less than the bare TiO2. For the photocatalytic degradation of methylene blue aqueous solution, based on the same amount of Ti species, the presence of SiO2 in the film could enhance the phtocatalytic activity exhibiting the rate constant of 3×10-3 min-1 and 1.518×10-3 min-1 under UVC (254 nm) for calcined and uncalcined ST(5) films. In addition, the photocatalytic reaction of ST(5) film was also active under UVA illumination (365 nm). Thus, this method can be the alternative way to produce the film coating on substrate which possesses high light transmittance and also preserves high photocatalytic activity simultaneously.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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