氧化锌光催化材料的合成及其光催化性能研究

发布时间：2018-05-03 19:55

本文选题：ZnO + 复合材料　；参考：《河南师范大学》2017年硕士论文

【摘要】：工业发展给人类带来了大量的好处,但是,它也对我们的生态系统造成了很多不利的影响。土壤,水和大气都被严重污染,人类的健康也随之受到了威胁。因此,消除这些污染迫在眉睫。迄今为止,光催化技术被认为是最现实的解决方案之一。近年来,ZnO因具有较低的价格,稳定的性能,无毒,高的量子效应等优点,已成为被广泛应用的光催化剂之一。结构决定性能,所以,制备不同形貌和结构的ZnO材料已成为研究者们炙手可热的课题。但是,在ZnO作为光催化剂的催化过程中,由于光生载流子的分离效率较低,并不能达到让人们满意的光催化效果。因此,为了提高ZnO光生e-和h+的分离效率,大量的研究正在被进行。Ag作为一种贵金属,可以作为光生e-的有效俘获陷阱,与ZnO复合能够快速地转移走ZnO表面的光生e-,从而有效地提高光生h+和e-的分离率,进而使ZnO的光催化性质得到提高。因此合成独特结构和优良性能的Ag/ZnO复合材料具有相当重要的科学意义。本文采用简单的溶剂热合成方法,合成出了多种形貌的ZnO以及ZnO与Ag的复合材料。主要工作如下:(1)选用乙醇和二乙二醇作为反应溶剂,Zn(NO_3)2.6H_2O作为Zn源,采用溶剂热法一步合成ZnO。通过调控溶剂比例分别合成了球状,碗状和花状的分级结构的ZnO。利用EDS,XRD,FESEM,HRTEM,BET,UV vis等测试手段对样品进行了表征,并对样品的形成机理进行了推测。实验选取亚甲基蓝(MB)作为目标污染物,在紫外光照射下,对所制备ZnO的光催化性能进行了研究。结果表明,当乙醇和二乙二醇的比为2:1时,合成的球状ZnO对MB的降解效率最高。(2)通过两次简单的溶剂热法合成了中空结构的球状Ag/ZnO复合材料。并对不同Ag修饰量的Ag/ZnO复合材料进行了各类表征。对Ag/ZnO复合物光催化性质的系统研究表明,Ag的修饰量不同,Ag/ZnO样品的光催化性质有很大不同。在UV光照射下,30%Ag/ZnO复合物对罗丹明B(RhB)的降解性能最佳。另外,在本章中,Ag/ZnO复合材料很好的催化循环稳定性能也得到了证明。(3)采用溶剂热法一步合成分级结构的空心球ZnO,在Ag_2CO_3作为Ag源的条件下,再利用一次溶剂热法合成Ag负载量不同的Ag/ZnO复合物,同时,ZnO的形貌和结构保持不变。通过样品在UV光下降解RhB和MB来评估所制备Ag/ZnO的光催化活性。Ag的负载量为20%的Ag/ZnO复合物对两种染料的降解效率最高。光照16分钟后,20%-Ag/ZnO对RhB的降解比例可达到99.3%,对MB的降解效率可达98.3%。值得注意的是,20%-Ag/ZnO复合物对实际污染物苯酚也具有很好的降解效果,50 mg/L的苯酚在紫外光照射60分钟后,几乎被完全降解。在本章最后,对可能的光催化机理以及样品的稳定性也进行了细致而深入地探究。
[Abstract]:Industrial development has brought a lot of benefits to mankind, but it has also had a lot of adverse effects on our ecosystems. Soil, water and atmosphere are seriously polluted and human health is threatened. Therefore, the elimination of these pollution is urgent. So far, photocatalytic technology is considered as one of the most realistic solutions. In recent years, ZnO has become one of the widely used photocatalysts because of its advantages of low price, stable performance, nontoxic and high quantum effect. The structure determines the properties, so the preparation of ZnO materials with different morphologies and structures has become a hot topic for researchers. However, in the process of ZnO as photocatalyst, because of the low separation efficiency of photogenerated carriers, it can not achieve satisfactory photocatalytic effect. Therefore, in order to improve the separation efficiency of ZnO photogenerated e- and h, a large number of studies are being carried out. Ag, as a precious metal, can be used as an effective trapping trap for photogenerated e-. The photocatalytic properties of ZnO can be improved by combining with ZnO to transfer the photogenerated e-on the surface of ZnO, thus effectively increasing the separation rate of photogenerated h and e-. Therefore, it is of great scientific significance to synthesize Ag/ZnO composites with unique structure and excellent properties. In this paper, various morphologies of ZnO and ZnO / Ag composites were synthesized by a simple solvothermal synthesis method. The main work is as follows: (1) ethanol and diethylene glycol are selected as the reaction solvent ZnNo3 and 2.6H _ 2O as Zn source, and ZnO _ 2O is synthesized by solvothermal method. Spherical, bowl and flower-like ZnO were synthesized by adjusting the solvent ratio. The samples were characterized by vis and the formation mechanism of the samples was speculated. The photocatalytic properties of ZnO prepared by UV irradiation were studied by using methylene blue blue (MBB) as the target pollutant. The results show that when the ratio of ethanol to diethylene glycol is 2:1, the spherical ZnO has the highest degradation efficiency of MB. 2) the hollow spherical Ag/ZnO composite was synthesized by two simple solvothermal method. All kinds of Ag modified Ag/ZnO composites were characterized. The systematic study on the photocatalytic properties of Ag/ZnO complexes shows that the photocatalytic properties of Ag / Ag modified samples are very different. The degradation of Rhodamine B _ (2) RhB by 30 Ag- / ZnO complex under UV irradiation is the best. In addition, in this chapter, the good catalytic cycling stability of Ag- / ZnO composite is also proved. The solvothermal method is used to synthesize the graded hollow sphere ZnO. Under the condition of Ag_2CO_3 as Ag source, The Ag/ZnO composites with different Ag loading amount were synthesized by single solvothermal method, while the morphology and structure of Ag/ZnO remained unchanged. The photocatalytic activity of Ag/ZnO was evaluated by the degradation of RhB and MB in UV light. The degradation efficiency of the two dyes was the highest when the loading of Ag/ZnO complex was 20%. After 16 minutes of illumination, the degradation rate of RhB and MB were 99.3and 98.3, respectively. It is worth noting that the complex of 20% -Agr / ZnO also has a good degradation effect on the actual pollutant phenol. The phenol of 50 mg/L is almost completely degraded after 60 minutes of ultraviolet irradiation. At the end of this chapter, the possible photocatalytic mechanism and the stability of the samples are also studied in detail.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O644.1

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