二维负载型纳米复合光催化材料的制备及其可见光催化性能的研究

发布时间：2018-04-30 18:48

  本文选题：二维负载型多组分催化剂 + Bi_2S_3/BiOCl　； 参考：《华东师范大学》2017年硕士论文

【摘要】：随着科技的进步,工业生产加速所带来的环境问题也日益受到社会的广泛关注。其中,工业排放的废水中因含有大量毒性强、稳定性高、难生物降解的有害物质,已经给生物体健康和环境保护带来了巨大危害。由于半导体光催化氧化技术具有操作简单、反应条件较容易实现且不会对环境产生的二次污染等优点,因此其在环境保护方面取得了广泛的关注。而光催化技术作为利用光能有效净化水污染的手段在环境方面有着巨大的发展空间,但目前它面临对可见光吸收有限以及光生电子和空穴易复合等问题。大量实验表明,多组分的复合材料比单组分的具有较高的活性。主要原因有匹配的能带结构以及能抑制光生电子和空穴的再复合。基于以上研究背景我们选择对二维负载型纳米复合光催化材料为研究对象,以提高光生电子-空穴分离为目标,开展了以下三方面的研究工作。一、利用甘露醇水热合成含有大量氧缺陷的BiOCl纳米片,再通过加入不同质量的硫代乙酰胺(TAA),采用离子交换法制备出Bi_2S_3/BiOCl复合光催化剂。根据光催化实验结果可知,当TAA加入的质量比为28.8%时,复合光催化剂显示了最优的光催化降解罗丹明B(RhB)的能力,分别是单一的BiOCl与Bi_2S_3的2.5和16倍。由捕获剂实验可知,此体系的主要活性物种为02.和h+,但·OH也有一定的影响,因此我们通过查阅相关的文献和基于所得的实验结果推测出Bi_2S_3/BiOCl反应机理。二、首先利用尿素通过马弗炉加热煅烧得到淡黄色固体g-C_3N_4,碾磨均匀之后再放于马弗炉再次煅烧得到剥片的g-C_3N_4,再采用沉淀法合成了g-C_3N_4/BiOCl复合物,随后利用TAA合成了 Bi_2S_3/g-C_3N_4/BiOCl复合物。当离子交换时间为0.5h时,所得样品的光催化效率最高,其光催化反应速率分别是单一的BiOCl与g-C_3N_4的2和13倍。由于g-C_3N_4与BiOCl能带隙结构匹配,再加上利用简单的离子交换法在BiOCl表面生成Bi_2S_3,大大提高了界面电荷的有效转移。捕获剂实验说明O_2·和h+为光催化过程中的活性物种,而·OH则不存在。查阅相关文献和基于所得的实验结果我们推测出Bi_2S_3/g-C_3N_4/BiOCl反应机理。三、首先利用HF水热合成片状的TiO_2,再通过利用片状的TiO_2作为结构诱导剂,在低温下一步合成二维TiO_2/ZnIIn2S4复合物。通过可见光光催化降解RhB探究出两者的最优配比为TiO_2/ZnIn2S =1/1,是单独ZnIn2S4反应速率的3.8倍。ZnIn2S4的负载导致TiO_2对可见光有吸收作用,另一方面也抑制ZnIn2S4光生电子和空穴的复合。
[Abstract]:With the development of science and technology, the environmental problems caused by the acceleration of industrial production are paid more and more attention by the society. Among them, industrial wastewater contains a large number of toxic, high stability, difficult to biodegradable harmful substances, has brought great harm to the health of organisms and environmental protection. Due to the advantages of semiconductor photocatalytic oxidation technology, such as simple operation, easy implementation of reaction conditions and no secondary pollution to the environment, the semiconductor photocatalytic oxidation technology has been widely concerned in the field of environmental protection. However, photocatalytic technology, as a means of effectively purifying water pollution by using light energy, has a great space for development in the field of environment, but at present it is faced with the problems of limited absorption of visible light and easy recombination of photogenerated electrons and holes. A large number of experiments show that the multicomponent composite has higher activity than that of single component. The main reasons are matching band structure and recombination of photogenerated electrons and holes. Based on the above research background, we selected the two-dimensional supported nano-composite photocatalytic materials as the research object, with the aim of improving photogenerated electron-hole separation, we carried out the following three aspects of research work. Firstly, BiOCl nanoparticles with large oxygen defects were synthesized by hydrothermal synthesis of mannitol, and then Bi_2S_3/BiOCl composite photocatalysts were prepared by ion exchange method by adding different quality thioacetamide (TAA). According to the results of photocatalytic experiments, when the mass ratio of TAA was 28.8wt%, the composite photocatalyst showed the best photocatalytic degradation ability of Rhodamine Bhh B, which was 2.5 and 16 times of that of single BiOCl and Bi_2S_3, respectively. The main active species of this system are 0 2. And h, but OH also has some influence, so we infer the mechanism of Bi_2S_3/BiOCl reaction based on the related literature and experimental results. Secondly, the yellowish solid g-C _ 3N _ 4 was obtained by heating and calcining with urea in muffle furnace to obtain g-C _ 3N _ 4, then the g-C _ 3N _ 3N _ 4 was calcined in a muffle furnace, then the g-C_3N_4/BiOCl complex was synthesized by precipitation method, and then the Bi_2S_3/g-C_3N_4/BiOCl complex was synthesized by TAA. When the ion exchange time is 0.5 h, the photocatalytic efficiency of the obtained sample is the highest, and the photocatalytic reaction rate is 2 and 13 times of that of the single BiOCl and g-C_3N_4, respectively. Because of the matching of the energy band gap structure between g-C_3N_4 and BiOCl, and by using the simple ion exchange method to generate Bi2S _ 3 on the surface of BiOCl, the effective transfer of interfacial charge is greatly improved. The trapping agent experiments show that O _ 2 and h are active species in photocatalytic process, but OH does not exist. We infer the mechanism of Bi_2S_3/g-C_3N_4/BiOCl reaction by consulting relevant literature and experimental results. Thirdly, firstly, TiO-2 was synthesized by hydrothermalization of HF, and then two-dimensional TiO_2/ZnIIn2S4 complex was synthesized at low temperature by using flake TiO_2 as structure inducer. It was found that the optimum ratio of TiO_2/ZnIn2S and ZnIn2S4 for the degradation of RhB by visible light was 1 / 1, which was 3.8 times of the rate of ZnIn2S4 reaction. The loading of ZnIn2S4 led to the absorption of visible light by TiO_2, on the other hand, it also inhibited the combination of photogenerated electrons and holes in ZnIn2S4.
【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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本文编号：1825744