钽酸盐复合光催化剂制备及其对四环素的降解性能研究

发布时间：2018-03-07 17:41

本文选题：钽酸钠　切入点：光催化　出处：《内蒙古大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,钽酸盐化合物在光催化方面表现出了优异的催化性能,特别是在光解水和光催化降解有机污染物方面,这引起了人们对钽酸盐催化剂的高度关注。但是,钽组酸盐的带隙一般较宽,只可吸收紫外光,可见光利用率低,即太阳能利用率低,这大大限制了其在实际中的应用。近几年,通过复合、贵金属沉积、金属及非金属离子掺杂等方法调控钽酸盐的光催化性能使其对可见光响应已成为半导体光催化领域的研究热点之一,同时这也为解决人类所面临的资源和环境问题提供了广阔的应用前景。本论文以钽酸钠(NaTaO3)和钽酸铋(Bi3TaO7)为主要研究对象,通过复合降低光生电子和空穴的复合率借以提高半导体光催化剂的光催化活性。本论文的研究内容可总结为以下几个方面:1.分别以水热法和回流法合成NaTaO3和氧化石墨烯(GO),然后再通过水热法制备出复合光催化剂NaTaO3/GO。通过XRD,TEM,FT-IR等测试表征其化合物由NaTaO3和GO组成。通过Raman测试,发现NaTaO3/GO的ID/IG值(ID/IG=1.26)有较GO(ID/IG=0.54)增大的趋势,说明由于NaTaO3的引入,在复合相中产生了较强的相互作用力,使得在GO结构中形成了更多的sp3缺陷。XPS测试表明复合相中C(C-O),C(C=O)和C(COOH)的数量显著下降,同时伴随有C(C-C)的大量增加,说明复合相NaTaO3/GO中GO发生了部分还原,这更加有利于电子的传输,以提高光催化效率。光电流测试结果和光催化降解四环素(TC)的数据也为上述论断提供了相应的佐证。2.水热法制备出一种新型半导体复合光催化剂WO3/NaTaO3。探究了不同量WO3复合的催化剂在可见光照射下对盐酸四环素的降解。与纯相WO3和NaTaO3相比,复合催化剂表现出更好的可见光催化降解四环素的活性,这是由于复合催化剂形成的球形异质结减少了载流子的复合。最后,通过实验结果分析,提出了一种可能的光催化反应机制。本章的研究为合成更环保、更新颖、更高效的催化剂提供了线索,并促进它们在环境修复方面的实际应用。3.混合焙烧方法合成了光催化剂Bi2O3/Bi3TaO7。在可见光照射下,通过对盐酸四环素降解的实验结果证明,随着Bi2O3复合量的增大,样品对盐酸四环素的氧化能力逐渐提高,但是当Bi2O3复合量增加到一定量时,复合光催化剂性能反而有所降低,Bi2O3/Bi3TaO7的最佳比例为2.0。这表明,一定量Bi2O3/Bi3TaO7的复合可以有效抑制电子-空穴对的重组,延长其存活寿命,提高光量子效率,从而进一步提高光催化效率。
[Abstract]:In recent years, tantalate compounds have shown excellent catalytic performance in photocatalysis, especially in photolysis of water and photocatalytic degradation of organic pollutants. The band gap of tantalum salt is generally wide, it can only absorb ultraviolet light, and the utilization ratio of visible light is low, that is, the utilization ratio of solar energy is low, which greatly limits its application in practice. The photocatalytic properties of tantalates by doping metal and nonmetallic ions have become one of the hot topics in the field of semiconductor photocatalysis. At the same time, it provides a broad application prospect for solving the problems of resources and environment faced by human beings. In this thesis, NaTaO3 (sodium tantalate) and Bi3TaO7 (bismuth tantalate) are the main research objects. The photocatalytic activity of semiconductor photocatalysts can be improved by reducing the recombination rate of photogenerated electrons and holes. The research contents of this thesis can be summarized as follows: 1. The synthesis of NaTaO3 and oxidation by hydrothermal method and reflux method respectively. Then the composite photocatalyst NaTaO3 / Go was prepared by hydrothermal method. The compounds were characterized by NaTaO3 and go by XRDX Tem FT-IR and Raman. It is found that the ID/IG value of NaTaO3/GO (ID / IGN 1.26) is higher than that of GOD / IGN (0.54), which indicates that there is a strong interaction force in the composite phase due to the introduction of NaTaO3. As a result, more sp3 defects were formed in the go structure. The results showed that the number of C _ (C) -O _ ((C)) and C _ (C _ (C)) in the composite phase decreased significantly, and at the same time, there was a large increase in the number of C _ (C) -C _ (C), which indicated that partial reduction of go in the composite phase took place, which was more favorable for the transport of electrons. In order to improve the photocatalytic efficiency, the photocurrent test results and the photocatalytic degradation of tetracycline TC3 data also provided the corresponding support for the above conclusions. 2. A new semiconductor composite photocatalyst WO3 / NaTaO3 was prepared by hydrothermal method. The degradation of tetracycline hydrochloride by WO3 composite catalyst under visible light irradiation was compared with that of pure phase WO3 and NaTaO3. The composite catalyst exhibits better catalytic activity for tetracycline degradation under visible light, which is due to the reduction of carrier composition due to the spherical heterojunction formed by the composite catalyst. Finally, the experimental results are analyzed. A possible mechanism of photocatalytic reaction is proposed. The research in this chapter provides clues for the synthesis of more environmentally friendly, novel and efficient catalysts. The photocatalyst Bi _ 2O _ 3 / Bi _ 3TaO _ 7 was synthesized by mixed roasting. The experimental results of tetracycline hydrochloric acid degradation under visible light showed that with the increase of Bi2O3 compound, The oxidation ability of the sample to tetracycline hydrochloride was gradually improved, but when the amount of Bi2O3 was increased to a certain amount, the performance of the composite photocatalyst decreased to 2.0, which indicated that the optimum ratio of Bi _ 2O _ 3 / Bi _ 3TaO _ 7 was 2.0. The recombination of a certain amount of Bi2O3/Bi3TaO7 can effectively inhibit the recombination of the electron-hole pair, prolong its survival life, improve the photoquantum efficiency and further improve the photocatalytic efficiency.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X505;O643.36

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