卤氧化铋纳米材料的固相化学合成及光催化性能

发布时间：2018-04-14 01:35

本文选题：固相反应 + 纳米材料　；参考：《新疆大学》2015年硕士论文

【摘要】：半导体光催化技术可将有机污染物直接降解为CO2、H2O以及其它一些无机小分子物质,具有高效和无二次污染等优点,从而受到化学、物理和材料学家的广泛关注。目前,对于半导体光催化剂的研究主要集中在对TiO2等传统光催化剂的改性和新型半导体光催化剂的开发。铋氧基光催化剂具有优异的可见光光催化活性和特殊的片状结构,近年来成为新型半导体光催化剂的研究热点。本论文采用操作简单的固相化学反应合成了几种卤氧化铋纳米光催化剂,系统研究了卤氧化铋纳米光催化剂在紫外光和可见光照射条件下对于目标污染物的降解性能,探讨了材料的形貌、比表面积以及带隙对光催化性能的影响。主要研究内容如下:(1)通过室温固相反应快速、简便地合成了BiOX(X=Cl、Br、I)二维纳米片,并通过改变反应微环境合成了纳米片构筑的具有三维分级结构的微米球,利用XRD、SEM、HRTEM、BET和固体UV~Vis等表征手段对样品的物相、形貌、比表面积和光学性质进行表征,并对其光催化性能进行了测试。无论在紫外光还是可见光下,BiOX二维纳米片和三维分级微米球都具有较好的光催化性能。Bi OCl微米球表现出比BiOCl纳米片更高的光催化活性,紫外光催化反应进行到13 min时对RhB降解完全,可见光催化反应进行到240 min时对RhB的降解效率达到90%。这主要归因于BiOCl微米球具有较大的比表面积,有利于对染料分子的吸附和传输,为光催化提供了更好的条件。在可见光下,BiOX微球对RhB的降解效率依次为Bi OClBiOBrBiOI。(2)通过室温固相反应合成了BiOClxI1-x(x=0.75,0.5,0.25)固溶体,该固溶体为二维纳米片组装而成的三维分级微米球。BiOCl0.75I0.25固溶体的比表面积为51.17 m2/g,禁带宽度为2.96 eV,在可见光条件下降解RhB的实验中表现出比单相催化剂更强的光催化降解能力,光催化反应进行120 min时对RhB的降解率达到96%。(3)通过两步固相反应合成了Bi24O31X10(X=Cl,Br)材料和BiOX/Bi24O31X10异质结材料。BiOX/Bi24O31X10异质结材料的颗粒尺寸小于单相Bi24O31X10(X=Cl,Br)材料,具有比单相Bi24O31X10(X=Cl,Br)更优异的光催化活性,这主要是由于Bi OX和Bi24O31X10之间形成的异质结界面处光生电子转移速率加快,进而光生电子-空穴的分离效率大大提高,致使异质结材料的光催化性能显著增强。
[Abstract]:Semiconductor photocatalysis technology can directly degrade organic pollutants to CO2H 2O and some other inorganic small molecules, which has the advantages of high efficiency and no secondary pollution, so it has been widely concerned by chemical, physical and material scientists.At present, the research of semiconductor photocatalyst mainly focuses on the modification of traditional photocatalyst such as TiO2 and the development of new semiconductor photocatalyst.Bismuth oxide based photocatalyst has excellent visible photocatalytic activity and special flake structure, so it has become a research hotspot of new semiconductor photocatalyst in recent years.In this paper, several kinds of bismuth halide nanocrystalline photocatalysts were synthesized by simple solid-state chemical reaction. The degradation performance of bismuth halide nano-photocatalysts to target pollutants under ultraviolet and visible light irradiation was systematically studied.The effects of morphology, specific surface area and band gap on photocatalytic performance were discussed.The main contents of this study are as follows: (1) BiOXX XClClCBI) two dimensional nanowires were synthesized by rapid solid state reaction at room temperature, and microspheres with three dimensional hierarchical structure were synthesized by changing the reaction microenvironment.The phase, morphology, specific surface area and optical properties of the samples were characterized by XRDD-SEM-HRTEMT-BET and solid UV~Vis, and their photocatalytic properties were tested.BiOX two dimensional and three dimensional graded microspheres have better photocatalytic properties. Bi OCl microspheres exhibit higher photocatalytic activity than BiOCl nanoparticles in both ultraviolet and visible light.The degradation of RhB was completely achieved by UV photocatalytic reaction for 13 min and 90% by visible light reaction for 240 min.This is mainly due to the large specific surface area of BiOCl microspheres, which is conducive to the adsorption and transport of dye molecules and provides a better condition for photocatalysis.The degradation efficiency of BiOX microspheres was BiOClBiOBrBiOI.2.The solid solution was synthesized by solid state reaction at room temperature.The solid solution was composed of two dimensional nanowires. The specific surface area of the solid solution was 51.17 m2 / g, and the band gap was 2.96 EV. The photocatalytic degradation of RhB was stronger than that of single-phase catalyst in the experiment of degradation of RhB under visible light, and the specific surface area of the solid solution was 51.17 m2 / g and the band gap was 2.96 EV.The degradation rate of RhB by photocatalytic reaction for 120 min was 96%. 3) Bi24O31X10XC1XC1Brand BiOX/Bi24O31X10 heterojunction material were synthesized by two-step solid state reaction. The particle size of BiOX / Bi24O31X10 heterojunction material was smaller than that of single-phase Bi24O31X10XClBr-based material, and the photocatalytic activity was better than that of single-phase Bi24O31X10XCClBr.This is mainly due to the acceleration of photoelectron transfer rate at the heterojunction between BiOX and Bi24O31X10, and the higher efficiency of photoelectron hole separation, resulting in a remarkable enhancement of photocatalytic performance of heterojunction materials.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ135.32;TB383.1

【共引文献】