铋系薄膜材料的电化学制备及其光催化性能的研究

发布时间：2018-06-23 01:40

本文选题：光催化 + 电化学合成　；参考：《南昌航空大学》2017年硕士论文

【摘要】：随着人口的增长、工业化与城镇化的加速,人们在生产、生活中对水环境造成了严重的污染。为了缓解水资源的匮乏与水环境的污染,人们开发了多种废水处理技术。光催化技术能够直接利用太阳能来去除水中的有机污染物、有害细菌以及某些重金属离子,所以它在目前被认为是一种非常有潜力的水处理技术。然而,由于TiO2等传统的光催化剂只能在太阳光中的紫外光谱区响应,使得光催化过程中太阳光的利用率较低。此外,目前光催化技术的研究中,人们制备的光催化剂大多数为纳米级的粉体材料,而这些粉体材料应用到水处理中时往往难以从溶液中分离循环利用,容易团聚,这给材料的重复利用带来了很大的难度,并且这些粉体的纳米材料也可能通过排放的水体进入水环境中进而对人体产生潜在的健康风险。针对上述的问题,本文探索了铋系光催化薄膜材料的设计与电化学合成,研究了不同的制备条件对光催化材料性能的影响以及铋系光催化剂在降解有机污染物方面的机理。本文的主要研究内容如下:1.通过简便快速的电化学的方法合成了树枝状的单质Bi膜,之后通过阳极氧化使得在Bi膜的表面原位生成了BiOBr纳米片,最终制得了树枝状的Bi/BiOBr薄膜材料。这种特殊形貌的Bi/BiOBr薄膜材料具有优异的吸附性能并且由于单质Bi的存在使得材料对光的吸收和光生电子与空穴的分离都得到了加强。通过XRD、SEM、DRS、手段对材料进行表征,发现Bi3+的浓度与施加的氧化电量能够明显的影响材料光催化的性能,结果表明在0.04M的Bi3+施加1.8C氧化电量的Bi/BiOBr材料在可见光照射下,90min内RhB的降解效率达到了98.9%,在材料的光催化反应中,空穴和超氧自由基起到了主要作用。2.首次将通过电化学制备的单质Bi薄膜应用于光催化降解无色污染物2,4-DCP,发现单质Bi薄膜本身具有光催化的能力,并且通过表征结果推测了单质Bi的能带结构与光催化的机理。利用XRD、SEM,DRS等表征手段对反应前后的单质Bi薄膜进行了表征。同时,我们发现调控Bi3+的浓度或者加入不同的表面活性剂都能够影响单质Bi的光催化性能,在Bi3+离子浓度为0.03并且加入0.1g PVP所制备的单质Bi的光催化活性最佳,在可见光照射下90min,2,4-DCP的降解率达到了76.5%。3.通过电化学方法制备树枝状的BiOCl后,在以KI为I源用离子交换法制备了树枝状形貌的可见光响应的BiOCl/BiOI复合薄膜材料。利用XRD、SEM,DRS等表征手段对反应前后的薄膜进行了表征。复合材料在可见光照射下,90min对RhB的光催化降解率为96.2%,明显高于单体的BiOCl或BiOI的光催化效果。复合材料光催化降解RhB的过程中,空穴、超氧自由基与羟基自由基都参与了反应并且空穴在光催化过程中起到了主要作用。
[Abstract]:With the increase of population and the acceleration of industrialization and urbanization, people have caused serious pollution to the water environment in production and life. In order to alleviate the shortage of water resources and the pollution of water environment, many wastewater treatment technologies have been developed. Photocatalytic technology can directly use solar energy to remove organic pollutants, harmful bacteria and some heavy metal ions in water, so it is considered to be a potential water treatment technology at present. However, because the traditional photocatalysts such as TiO2 can only respond in the ultraviolet spectrum region of the solar light, the utilization ratio of the solar light in the photocatalytic process is low. In addition, at present, in the research of photocatalytic technology, most of the photocatalysts prepared by people are nano-sized powder materials, and when these powder materials are applied to water treatment, it is often difficult to separate and recycle from the solution, so it is easy to agglomerate. This brings great difficulty to the reuse of the materials, and the nano-materials of these powders may also enter the water environment through the discharged water, thus creating potential health risks to the human body. In order to solve the above problems, the design and electrochemical synthesis of bismuth based photocatalytic thin films were investigated. The effects of different preparation conditions on the performance of photocatalytic materials and the mechanism of bismuth photocatalysts in the degradation of organic pollutants were studied. The main contents of this paper are as follows: 1. The dendritic Bi films were synthesized by a simple and rapid electrochemical method. Then BiOBr nanocrystals were formed on the surface of Bi films by anodizing. Finally, the dendritic Bi / BiOBr thin films were prepared. The Bi / BiOBr thin film with special morphology has excellent adsorption properties and the absorption of light and the separation of photogenerated electrons and holes are strengthened due to the existence of simple Bi. The material was characterized by means of XRDX SEM DRS. It was found that the concentration of Bi3 and the amount of oxidizing electricity applied could significantly affect the photocatalytic performance of the material. The results showed that the degradation efficiency of RhB reached 98.9 in 90 min under visible light irradiation for Bi-P / BiOBr material with 1.8C oxidized electricity at 0.04M Bi3. Hole and superoxide radical played a major role in the photocatalytic reaction of the material. For the first time, the Bi thin films prepared by electrochemistry were applied to photocatalytic degradation of colorless pollutants 24-DCP.The results show that the Bi thin films have photocatalytic ability, and the energy band structure and photocatalytic mechanism of pure Bi are inferred from the characterization results. Simple Bi films before and after the reaction were characterized by means of XRDX SEMX DRS and so on. At the same time, we found that controlling the concentration of Bi _ 3 or adding different surfactants can affect the photocatalytic performance of Bi, and the photocatalytic activity of Bi _ (2) prepared by adding 0.1 g PVP and Bi _ (3) ion concentration was the best, and the photocatalytic activity of Bi was the best when the concentration of Bi _ (3) was 0.03 and 0.1 g PVP was added. Under visible light irradiation, the degradation rate of 4-DCP reached 76.50.3. After the dendritic BiOCl was prepared by electrochemical method, the BiOCl / BiOI composite films with dendritic morphology were prepared by ion exchange method using Ki as the source. The films before and after the reaction were characterized by means of XRDX SEMX DRS and so on. The photocatalytic degradation rate of RhB was 96.2cm under visible light irradiation for 90 min, which was obviously higher than that of the monomer BiOCl or BiOI. In the photocatalytic degradation of RhB, holes, superoxide radicals and hydroxyl radicals are involved in the photocatalytic degradation of RhB, and holes play a major role in the photocatalytic process.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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