本文選題：TiO2-ZnO復合薄膜　切入點：離子摻雜　出處：《濟南大學》2015年碩士論文　論文類型：學位論文

【摘要】：二氧化鈦是一種催化活性高、無毒無污染、價格低廉、性質(zhì)穩(wěn)定的n型半導體光催化劑,然而,TiO2存在兩大方面的缺陷:一是TiO2的禁帶寬度比較大,帶隙能為3.2eV,也就是說二氧化鈦只有在受到波長小于387.5nm的紫外燈照射時才會激發(fā)產(chǎn)生光生電子和空穴,但是紫外光在太陽光中所占的比例還不足5%,這使二氧化鈦在日常應用中對太陽光的利用率極低;二是光生電子和空穴很不穩(wěn)定且非常容易發(fā)生復合,這嚴重降低了二氧化鈦的光催化性能。從而,減小帶隙能和降低電子空穴對的復合率成為了拓寬TiO2的應用領域及改善其光催化活性的重要突破口。為了實現(xiàn)上述突破,必然要對TiO2進行改性研究。迄今為止,研究者已經(jīng)研制出許多應用于TiO2改性的方法,其中離子摻雜和半導體復合是我們在本研究中所采用的兩種改性方法,改性處理不僅將TiO2的光響應范圍拓寬到可見光區(qū)域,而且大大降低了光生電子-空穴對的復合率。本論文主要研究了以下幾個方面:(1)TiO2薄膜及TiO2-ZnO復合薄膜的制備及性能測試該實驗選用鈦酸四正丁酯和二水合醋酸鋅分別作為鈦源和鋅源,采用溶膠-凝膠法制備出TiO2膠體和ZnO膠體,將陳化好的膠體按一定體積混合攪拌得到TiO2-ZnO復合膠體,采用浸漬提拉法在潔凈干燥的玻璃基體上拉制薄膜,待薄膜干燥后,采用外摻雜的方法在其表面摻雜離子Ce、F、Ca、Fe、La,待離子溶液自然風干后,將薄膜置于馬弗爐中進行高溫焙燒,通過對甲醛的降解性能測試來確定離子的最佳單雙摻濃度。薄膜對有機污染物降解的實驗結(jié)果表明了離子摻雜復合改性之后的TiO2薄膜光催化活性得到了顯著的提高。(2)TiO2及TiO2-ZnO光催化劑的表征本研究通過使用紫外-可見分光光度計(UV-vis)、熒光光譜(PL)儀、場發(fā)射掃描電鏡(FE-SEM)、差熱-熱重分析儀(DTA-TG)、X射線衍射儀(XRD)及氮氣吸附-脫附儀(BET),對薄膜和粉體進行了一系列的光學性能及結(jié)構(gòu)表征。紅移及熒光光譜分析結(jié)果表明了:離子摻雜和復合改性不僅誘發(fā)了薄膜較強的可見光吸收,而且降低了電子-空穴對的復合率;DTA-TG及XRD結(jié)果顯示了改性后的催化劑晶型主要維持在光催化性能最好的銳鈦礦;FE-SEM及BET測試揭示了復合改性的薄膜是由較小的納米粒子構(gòu)成的,同時具有較大的比表面積。(3)光催化機理的探討首先,ZnO與TiO2復合后會形成交錯能級,經(jīng)光照射時,ZnO導帶上的電子會很容易地被激發(fā)到TiO2的導帶上,相反,TiO2價帶上產(chǎn)生的空穴會轉(zhuǎn)移到ZnO的價帶上,因此ZnO復合后大大降低了TiO2的帶隙能及電子-空穴的復合率。其次,半徑較小的離子摻雜后會與TiO2形成摻雜能級,從而進一步減小其帶隙能;半徑較大的鑭系金屬離子摻雜后會引起TiO2的晶格扭曲,使其能夠接收更多的光生空穴并產(chǎn)生更多的自由基來氧化吸附的有機污染物分子。另外,摻雜的離子可以結(jié)合電子或空穴,阻止其復合的進行。(4)應用領域的拓展與以往研究不同,本研究將離子摻雜后的TiO2-ZnO復合薄膜主要應用于甲醛這一新興污染物的降解,使其在實際生活中更加具有應用價值。
[Abstract]:Titanium dioxide is a high catalytic activity, non-toxic and pollution-free, low price, the N type semiconductor photocatalyst, stable however, defects of TiO2 in two aspects: one is the band gap of TiO2 is relatively large, the band gap energy of 3.2eV, that is to say only by TiO2 UV light wavelength is less than 387.5nm when irradiated to stimulate production of photogenerated electrons and holes, but the UV light accounted for in the light of the sun in the proportion of less than 5%, which makes the daily application of titanium dioxide in the sunlight utilization rate is extremely low; the two is the photogenerated electrons and holes are very unstable and very prone to complex, which greatly reduces the photocatalytic performance titanium dioxide. Thus, reducing the band gap energy and reduce the electron hole pair recombination rate is to widen the application fields of TiO2 and improve an important breakthrough in the photocatalytic activity. In order to realize the breakthrough, must be modified TiO2. Study. So far, the researchers have developed many applications on TiO2 modification methods, including ion doping and semiconductor composite is two kinds of modified methods we used in this study, the modification will not only widen the range to the visible light region in response to the TiO2 light, but also greatly reduces the photogenerated electrons hole pair recombination rate. This paper mainly studies the following aspects: (1) preparation and performance test of TiO2 film and TiO2-ZnO composite film of the experiment using butyl titanate four and two hydrated zinc acetate were used as titanium source and zinc source, using sol-gel method to prepare TiO2 and ZnO colloid. Chen Huahao colloid according to a certain volume mixing TiO2-ZnO Composite Colloid by dip coating method on glass substrate drawing clean dry film, the film after drying, using the method of doping on the surface of doped ion Ce, F, Ca Fe, La, for ion solution of natural dried, the film in the muffle furnace for high temperature roasting, the degradation of formaldehyde test to determine the optimal concentration of doped ions. Single and double film on degradation of organic pollutants and the experimental results show that the ion doped TiO2 thin film photocatalytic activity after greatly improved. (2) characterization of photocatalyst TiO2 and TiO2-ZnO in this study by using UV visible spectrophotometer (UV-vis), fluorescence spectroscopy (PL) spectrometer, field emission scanning electron microscopy (FE-SEM), thermogravimetric analyzer (DTA-TG), X ray diffraction (XRD) and nitrogen adsorption desorption instrument (BET), on thin films and powders were optical properties and structural characterization of a series of red shift and fluorescence spectra. The analysis results show: ion doping and composite modified films not only induced a strong absorption of visible light, but also reduce the electron hole pair complex Photosynthetic rate; DTA-TG and XRD results showed that the modified catalyst crystal after mainly maintained in the best photocatalytic activity of anatase; FE-SEM and BET test revealed a thin film composite modification is composed of smaller particles, and has a high surface area. (3) to investigate the photocatalytic mechanism of the first. ZnO and TiO2 compound will be formed after the level crossing, after light irradiation, ZnO electronic conduction band can be easily excited into the conduction band of TiO2, on the contrary, TiO2 will be transferred to the valence band holes on the valence band of ZnO, so the ZnO composite greatly reduces the recombination rate of TiO2 band gap energy and electron hole. Secondly, ion doping smaller radius will be formed after the doping level and TiO2, so as to further reduce its energy gap; the radius of lanthanide metal ions doping will lead to larger distortion of the crystal lattice of TiO2, so that it can receive more and more photohole Organic pollutants to free radical oxidation and adsorption. In addition, the doping ions with electrons or holes, prevent the composite. (4) the application development different from previous studies, this study will degrade TiO2-ZnO composite film after ion doping is mainly applied to formaldehyde this emerging pollutants, the it has more application value in real life.

【學位授予單位】：濟南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB383.2

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相關期刊論文 前1條

1 孫曉君,蔡偉民,井立強,周德瑞,沈雄飛,王志平;二氧化鈦半導體光催化技術(shù)研究進展[J];哈爾濱工業(yè)大學學報;2001年04期

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本文編號：1603006