新型光催化薄膜材料的制备及其光催化性能的研究

发布时间：2018-03-01 01:37

本文关键词： 介孔单晶TiO_2 氢气贵金属负载光催化降解 ZnO 压电　出处：《上海师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,随着全球能源的过度消耗和环境的日益恶化,能源和环境问题是目前世界各国普遍面临而亟待解决的两大问题。光催化技术可用于全分解水制氢以及净化环境污染物而得到广泛关注。氢气作为高能燃料,越来越受到人们的关注,是理想的清洁能源。光催化制氢是一种成本低廉、集光转换与能量存储于一体的现代技术。光催化技术对环境污染物的净化处理具有独特的优势,在环保和环境治理方面具有重大的研究意义。目前光催化材料研究存在的主要问题包括:(1)研究工作主要集中在粉体催化剂,其存在的主要缺点是分离困难,开发薄膜光催化材料是解决上述问题方法之一;(2)光催化材料本身的光响应范围影响光催化材料对太阳光的利用,拓宽其光吸收范围是研究重点;(3)光生电子和空穴的复合是影响光催化剂性能的主要因素之一,如何设计有效的光催化剂结构,促进光生电子和空穴的分离,是光催化技术应用的关键。本论文针对光催化材料存在的上述关键问题进行了以下三方面的研究:(1)利用拓扑转化法制备介孔单晶二氧化钛薄膜;介孔单晶材料有着多孔、大比表面积和单晶结构,有利于电子传输的共同优点,能够显著的提高光催化性能。本节通过调变Ti与F的比和煅烧温度对薄膜的形貌和晶相进行了调控;利用XRD、SEM、TEM、XPS等现代分析技术对薄膜的结晶度、晶型、形貌等进行了分析,并以乙二醇为牺牲剂、硫酸钠为电解质,对介孔单晶TiO2的光电催化产氢活性进行了测试。(2)利用拓扑转化法制备了Au纳米颗粒修饰的介孔单晶TiO2薄膜;在可见光下,Au纳米颗粒对可见光(400-800 nm)具有等离子共振效应,较多的界面热电子会在Au纳米粒子表面产生,使热电子从Au纳米粒子表面转移到二氧化钛的导带上,肖特基势垒不仅有助于热电子聚集在TiO_2的导带上,而且能有效防止热电子重新返回到Au表面,从而使光催化产生的电子和空穴易于分离,显著提高了样品在可见光下的光催化性能。(3)压电驱动光生电荷的分离是一个非常有效的提高光催化剂催化效率的方式。我们在这一节中研究了流体诱导ZnO压电性对其光催化性能的影响;制备ZnO纳米棒阵列垂直生长在三维泡沫镍衬底上,通过控制磁力搅拌器的搅拌速率,使液体在Ni泡沫骨架之间形成涡流,溶液的流动导致纳米棒端面形变,从而激发ZnO阵列压电效应,驱动ZnO光生电子和空穴的分离,提高其光催化活性。实验结果表明提高搅拌速率,可以显著提高有机污染物的光催化氧化速率。这项工作为设计和制造新的压电催化材料提供了一种新的思路。
[Abstract]:In recent years, with the excessive consumption of global energy and the worsening of the environment, Energy and environment problems are two major problems that countries all over the world are facing and need to be solved. Photocatalytic technology can be used in total decomposition of water to produce hydrogen and purify environmental pollutants. Hydrogen is used as a high-energy fuel. Photocatalytic hydrogen production is a modern technology with low cost and integrated light conversion and energy storage. Photocatalytic technology has unique advantages in the purification and treatment of environmental pollutants. It is of great significance in the field of environmental protection and environmental control. At present, the main problems in the research of photocatalytic materials include: 1) the research work is mainly focused on powder catalysts, and its main disadvantage is the difficulty of separation. The development of thin film photocatalytic materials is one of the methods to solve the above problems. Broadening the range of photoabsorption is one of the main factors that influence the performance of photocatalyst. How to design an effective structure of photocatalyst to promote the separation of photogenerated electrons and holes is one of the main factors that affect the performance of photocatalyst. In this paper, the following three aspects of research on the above key problems of photocatalytic materials are carried out: 1) the mesoporous single crystal TIO _ 2 thin films are prepared by topological transformation method, and the mesoporous single crystal materials are porous. Large specific surface area and single crystal structure are beneficial to the common advantages of electron transport and can significantly improve the photocatalytic performance. In this section, the morphology and crystal phase of the films are regulated by adjusting the ratio of Ti to F and calcining temperature. The crystallinity, crystal form and morphology of the films were analyzed by means of modern analysis techniques such as XRDX, SEMX, TM, XPS, etc., with ethylene glycol as the sacrificial agent, sodium sulfate as electrolyte, etc. The photocatalytic hydrogen production activity of mesoporous single crystal TiO2 was tested. 2) au nanoparticles modified mesoporous single crystal TiO2 thin films were prepared by topological transformation method, and au nanoparticles exhibited plasmon resonance effect on visible light of 400-800 nm. A large number of interface hot electrons are produced on the surface of au nanoparticles, which makes the hot electrons transfer from au nanoparticles to the conduction band of titanium dioxide. Schottky barrier not only helps the hot electrons to accumulate in the conduction band of TiO_2. Moreover, it can effectively prevent hot electrons from returning back to the au surface, which makes the electrons and holes produced by photocatalysis easy to separate. It is a very effective way to improve the photocatalytic efficiency of photocatalyst by improving the photocatalytic performance of the sample under visible light. We have studied the piezoelectric properties of fluid-induced ZnO in this section. The effect on photocatalytic performance; The ZnO nanorod arrays were grown vertically on three dimensional foamed nickel substrates. By controlling the stirring rate of the magnetic agitator, the liquid formed eddies between the Ni foam skeletons, and the flow of the solution resulted in the end deformation of the nanorods. Thus, the piezoelectric effect of ZnO array is excited, the separation of photogenerated electrons and holes is driven, and the photocatalytic activity of ZnO is improved. The experimental results show that the agitation rate is increased. The photocatalytic oxidation rate of organic pollutants can be significantly increased. This work provides a new idea for the design and manufacture of new piezoelectric catalytic materials.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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