锶掺杂氧化锌光催化材料的制备及其可见光催化性能研究

发布时间：2018-04-10 04:25

本文选题：锶掺杂　切入点：氧化锌　出处：《华东师范大学》2017年硕士论文

【摘要】：近年来,随着人类大规模化的生产和社会的快速发展,不可再生能源短缺危机以及环境恶化等问题越来越严峻,如此破坏自然平衡,终会遭到反噬,必然危害人类自身,因此,开发清洁能源和推进可持续发展势在必行。半导体光催化技术作为一种新型绿色技术,它以太阳能作为能源,是用于解决有机污染物对生态造成的破坏的最有前景的技术之一,因此,受到研究者的广泛关注。氧化锌(ZnO)具有直接带隙(Eg=3.37eV)、较高的氧化还原电位以及较高的电子迁移率,是半导体光催化研究领域中的一种重要材料。研究发现,碱土金属离子掺杂可以有效地改善半导体光催化剂的光催化性能。然而,关于锶掺杂氧化锌可见光光催化性能的研究鲜有报道。因此,对锶掺杂氧化锌光催化材料进行研究,对发展实用、高效的可见光光催化材料具有重要的意义。本文采用溶胶凝胶法制备了不同Sr掺杂量的系列ZnO(SZO)粉体。X射线衍射(XRD)结果表明,制备的粉体样品均为六角纤锌矿ZnO结构,具有良好的结晶度。X射线光电子能谱(XPS)表明Sr以二价锶离子(Sr2+)的形式存在于ZnO晶格中。扫描电镜(SEM)结果表明,Sr掺杂之后,SZO粉体样品微观形貌发生变化、粒径减小。元素分析(EDS Mapping)结果表明,Sr元素在SZO粉体中近均匀分布,结合XRD和XPS的分析结果,进一步说明了 Sr2+已经掺杂进ZnO晶格。紫外可见漫反射光谱(DRS)表明,Sr掺杂提高了 SZO粉体的可见光吸收性能。光致发光谱(PL)表明,随着Sr掺杂量的增加,可以观察到样品的发光峰强度减弱。光催化性能评价实验表明,Sr掺杂导致SZO粉体样品比未掺杂的ZnO具有更高的光催化活性。其中,F1样品(前驱体溶液中Sr与Zn摩尔比为1%)对罗丹明B(RhB)染料表现出最高的光降解效率,在氙灯照射70 min后,RhB染料降解率达97.61%,其可见光催化降解RhB的反应速率约为未掺杂ZnO 的 2.53 倍。另外,考虑到在使用粉体降解有机污染物时,容易造成材料浪费或二次污染,为有效地解决这一问题,本文还采用超声辅助喷雾热解法,在玻璃基底上沉积了一系列不同Sr掺杂量的ZnO(SZO)薄膜。XRD结果表明,薄膜样品均为六角纤锌矿ZnO结构,且具有(002)择优取向,没有观察到Sr、SrO和ZnSr02等有关的衍射峰出现,说明Sr2+可能掺入了 ZnO晶格中。EDS Mapping分析表明,Sr元素在SZO薄膜中近均匀分布。UV-Vis吸收谱结果表明,相比ZnO薄膜,SZO薄膜在可见光区的光吸收性能增强。PL谱显示,随着Sr掺杂量的增加,SZO薄膜的绿发光峰明显增强。光催化降解RhB染料的实验结果表明,Sr掺杂有利于ZnO薄膜可见光催化效率的提高。所有薄膜样品中,S3薄膜样品(前驱体溶液中Sr、Zn摩尔比为3%)对RhB染料表现出91.99%的最高光降解效率,此外,还对SZO薄膜样品进行了不同温度下的空气退火处理,PL谱结果进一步验证了薄膜的绿光发射峰与VO缺陷有关。
[Abstract]:In recent years, with the large-scale production of human beings and the rapid development of society, the problems such as the shortage of non-renewable energy and the deterioration of the environment are becoming more and more serious.It is imperative to develop clean energy and promote sustainable development.As a new green technology, semiconductor photocatalytic technology, which uses solar energy as energy, is one of the most promising technologies to solve the ecological damage caused by organic pollutants.Zinc oxide (ZnO) has a direct band gap of 3.37 EV, high redox potential and high electron mobility. It is an important material in the field of semiconductor photocatalysis.It is found that alkali earth metal ion doping can effectively improve the photocatalytic performance of semiconductor photocatalysts.However, there are few reports on the visible photocatalytic properties of strontium doped zinc oxide.Therefore, the study of strontium doped zinc oxide photocatalytic materials is of great significance to the development of practical and efficient visible light photocatalytic materials.In this paper, a series of ZnOSZO powders with different Sr doping contents were prepared by sol-gel method. The results of X-ray diffraction show that all the prepared powders have hexagonal wurtzite ZnO structure.Good crystallinity. X-ray photoelectron spectroscopy (XPS) indicates that Sr exists in ZnO lattice in the form of Sr ~ (2 +).The SEM results showed that the microstructure of SZO powder changed and the particle size decreased after Sr doping.The results of elemental analysis show that the element of Sr is nearly uniformly distributed in SZO powders. Combined with the results of XRD and XPS, it is further demonstrated that Sr2 has been doped into ZnO lattice.UV-Vis diffuse reflectance spectroscopy (DRS) shows that Sr doping improves the visible light absorption of SZO powders.Photoluminescence spectra (PLL) show that the intensity of luminescence peak decreases with the increase of Sr doping content.The results of photocatalytic performance evaluation showed that the doped SZO powder had higher photocatalytic activity than the undoped ZnO powder.The F _ 1 sample (Sr / Zn molar ratio of 1 in precursor solution) exhibited the highest photodegradation efficiency for Rhodamine Bhh _ (B) dyes.After irradiation of xenon lamp for 70 min, the degradation rate of RhB dye was 97.61%, and the reaction rate of RhB degradation by visible light was about 2.53 times as high as that of undoped ZnO.In addition, in order to solve this problem effectively, the ultrasonic assisted spray pyrolysis method is used to solve the problem, considering that it is easy to cause material waste or secondary pollution when the powder is used to degrade organic pollutants.A series of ZnO SZO thin films with different Sr doping contents were deposited on glass substrates. The results show that the samples are hexagonal wurtzite ZnO structure and have a preferred orientation of zn002). No diffraction peaks related to SrO, ZnSr02 and so on have been observed.The results indicate that Sr2 may be doped into ZnO lattice. The results of UV-Vis absorption spectra show that the near uniform distribution of Sr elements in SZO films shows that compared with ZnO thin films, the optical absorption properties of ZnO thin films in visible region are better than that of ZnO thin films, and the results of UV-Vis spectra show that the optical absorption properties of SZO thin films are better than that of ZnO thin films in the visible region.The green luminescence peak of SZO thin films increases with the increase of Sr doping content.The experimental results of photocatalytic degradation of RhB dyes show that Sr doping is beneficial to the enhancement of visible light catalytic efficiency of ZnO films.In all thin film samples, the S3 film (Sr-Zn molar ratio in precursor solution is 3) exhibits the highest photodegradation efficiency of 91.99% for RhB dyes.The green emission peaks of SZO films were further verified to be related to VO defects by air annealing at different temperatures.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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