摘 要

 

随着工业社会的发展，人类在获得巨大经济收益的同时环境污染问题日益严重，威胁人类安全及生物界赖以生存的生存环境，其中有机废水作为水污染的主要原因一直是人类广泛关注的社会问题。光催化技术作为治理水污染的重要手段也是国内外科研学者的研究热点。BiFeO3作为一种典型钙钛矿结构的半导体材料，其窄带隙的特点使得它在可见光范围内具有良好的光响应特性，在光催化领域具有潜在的应用前景。不幸的是BiFeO3载流子的迁移率低、光生电子-空穴的复合率高以及弱磁性导致的催化剂的浪费等原因使得铁酸铋在光催化领域的应用受到限制。为了提高BiFeO3的光催化效率，人们通过多种方法对其进行改性，其中金属离子掺杂是最常见的一种改性方法。

 

本论文通过溶胶-凝胶方法，首先制备了不同钛掺杂浓度Ti-BiFeO3样品，探究钛掺杂铁酸铋提高光催化性能的最佳掺杂浓度，进而研究了钛掺杂铁酸铋对晶相结构、表面形貌及颗粒尺寸、原子组成、化学状态、能带间隙，光催化性能的影响，从而总结实验数据提出微观机理，并对钛掺杂浓度为10%的Ti-BiFeO3光催化材料的稳定性进行研究，发现连续五次光降解实验中，仍然能够保持高效的光催化效率，对光催化材料的实际应用具有重要意义。实验结果表明，钛掺杂浓度对反应过程中产生的Bi2Fe4O9起到调控作用，BiFeO3/Bi2Fe4O9异质结的存在使得电子-空穴的分离效率提高，有效的抑制了光生载流子的复合，促进了光催化效率的提高；以光催化效果最好的钛掺杂浓度为10%的样品作为研究对象，研究了煅烧温度对Ti-BiFeO3材料结构、表面形貌及原子比例、光催化性能的影响，实验结果表明Bi2Fe4O9含量可以通过控制煅烧温度进行调控，适量的Bi2Fe4O9含量使得光催化材料表面相对蓬松，有利于光催化效率的提高；其次研究发现络合物含量、浓硝酸含量等实验参数均能对Ti-BiFeO3光催化剂的结构及光催化性能产生影响。

 

关键词：光催化； 铁酸铋； 掺杂； 溶胶-凝胶；

 

Abstract

 

With the development of industrial society,the environmental pollution problem has become more and more serious while obtaininggreat economic benefits, which threatens human security and the living environment on which the biological community depends, among which organic waste water as the main cause of water pollution has been a social problem of wide concern to mankind. Photocatalytic technology,as an important mean to control water pollution, is also a hot research topic for researchers at home and abroad. BiFeO3, as a semiconductor material with a typical perovskite structure,has the characteristics of narrow band gap,which makes it have good light response characteristics in the visible light range and potential application in the field of photocatalysis. Unfortunately, the low migration rate of BiFeO3 carriers,the high combination rate of photogenerated electrons andholes, and the waste of catalysts caused by weak magnetism limit the application of BiFeO3 in the field of photocatalysis. In order to improve the photocatalytic efficiency of BiFeO3,it has been modified by many methods, of which metal ion doping is the most common method of change.

 

Through the sol-gel method, this paper first prepares samples of Ti-BiFeO3 with different titaniumdoping concentrations, The effects of titanium doping BiFeO3 on crystalline structure,surface shape and particle size, atomic composition, chemical state,energy gap and photocatalytic properties are studied, so as to summarize the experimental data and put forward the microscopic structure. The stability of Ti-BiFeO3 with titanium doping concentration of 10% is studied, and it is found that the high photocatalytic efficiency can still bemaintained in five consecutive photodegradation experiments,which is of great significance to the practical application of photo-catalytic materials. The experimental results show that titanium doping concentration will have a regulatory effect on Bi2Fe4O9 produced during thereaction process, and the presence of BiFeO3/Bi2Fe4O9 heterojunction makes the separation efficiency of electrons and holes increase, effectively suppress the combination and promote the improvement of photocatalytic efficiency;Taking the sample with the best photocatalytic effect of titanium doping concentration of 10% as theresearch object, the effect of calcination temperature on titanium doped BiFeO3 material structure, surface morphological and atomic ratio, photocatalytic performance was studied. The experimental results show that the content of Bi2Fe4O9 can be regulated by controlling the calcination temperature, and the appropriate amount of Bi2Fe4O9 makes the surface of photocatalytic material relatively fluffy, which is conducive to the improvement of photocatalytic efficiency；Secondly, it is found that experimental parameters such as complex content and concentrationnitric acid content can have an effect on the structure and photocatalytic properties of Ti-BiFeO3 photocatalysts.

 

Key words: Photocatalysis; BiFeO3; doped; Sol-gel;