BiOI的形貌调控、贵金属负载及其光催化活性

发布时间：2018-01-11 00:24

  本文关键词：BiOI的形貌调控、贵金属负载及其光催化活性　出处：《淮北师范大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 半导体光催化 BiOI 形貌调控 光催化活性

【摘要】：近年来，半导体光催化在环境污染治理方面获得了广泛的关注。作为新型的半导体光催化剂BiOI，因其特殊的层状结构带来的良好光催化性能，使其成为具有应用潜力的对象之一。但是由于BiOI较窄的禁带宽度（~1.75eV），使得光生电子-空穴对容易复合，大大降低了其光催化效率。因此，本论文旨在对BiOI进行形貌调控和贵金属负载，设计具有高活性的BiOI光催化剂，并通过系统的表征手段研究其光催化性能增强机制。 主要研究内容和结论如下： （1）通过室温直接水解法合成了一系列不同尺寸的二维片状BiOI。KI溶液的体积和浓度之间的协同效应显著影响了片状BiOI的尺寸和分散性。XRD结果分析表明，所有的BiOI样品均为结晶性较好的四方晶系。在可见光下（λ400nm），，通过甲基橙的降解评价了BiOI样品的光催化活性。结果表明，当KI溶液浓度为0.035mol/L时，所制备的BiOI具有最佳的光催化性能，甲基橙的降解率达到92.6%。本实验为获得高活性的片状BiOI光催化剂提供了简单的制备策略，可用于去除污水中的有机污染物。 （2）室温条件下，利用乙二醇辅助水解法制备了分等级结构的三维花状BiOI光催化剂。表征并分析了BiOI样品的形貌、元素组成、晶体相结构和光学特征。结果表明，乙二醇的浓度大小是调控BiOI样品形貌的主要因素。在可见光下（λ400nm），花状结构的BiOI(S10)在降解甲基橙的实验中表现出最佳的光催化活性，所对应的准一级速率常数为0.826h-1。BiOI样品光催化活性的变化趋势与光电流性能相一致。本实验为制备光催化性能优异的三维花状BiOI提供了有益参考。 （3）分别以二维片状和三维花状BiOI为载体，通过简单的光沉积法合成了Ag/BiOI复合光催化剂。阐述了两种形貌的BiOI载体对Ag量子点的生长过程及其Ag/BiOI光催化活性的影响。在光沉积过程中，二维片状BiOI具有较弱的载流子分离效率，促进了较大尺寸的Ag量子点生成，导致光生电子捕获效率提高，光催化活性显著增强。相比之下，三维花状BiOI表面的Ag量子点尺寸较小，对应的Ag/BiOI光催化活性增强较低。在降解甲基橙实验中，片状和花状BiOI的准一级速率常数分别为0.32和0.85h-1，Ag/BiOI的光催化活性分别是对应BiOI的3.25和1.11倍。在降解苯酚时，Ag/BiOI的光催化活性分别是对应BiOI的1.31和1.13倍。以上结果表明，调控载体形貌是改善Ag/BiOI以至更广泛的贵金属/半导体复合物光催化活性的有效手段。
[Abstract]:In recent years, semiconductor photocatalysis has been widely concerned in environmental pollution control. As a semiconductor photocatalyst BiOI model, good photocatalytic properties due to its special layered structure, making it one of the objects with potential applications. But because of the narrow band gap of BiOI (~1.75eV), the photogenerated electrons - hole on the composite, and greatly reduce the photocatalytic efficiency. Therefore, this paper aims at the BiOI morphology control and noble metal loading, BiOI optical design of catalyst with high activity, and characterized by means of the research on its photocatalytic performance enhancement mechanism.
The main contents and conclusions are as follows:
(1) at room temperature by the direct hydrolysis of the synthesis of synergistic effect between volume and concentration of a series of different size of the two-dimensional sheet of BiOI.KI solution significantly affected the size and dispersion of flake BiOI.XRD results showed that all the BiOI samples are well crystallized in tetragonal system. Under visible light (lambda 400nm) BiOI, the photocatalytic activity of samples was evaluated by the degradation of methyl orange. The results showed that when the concentration of KI was 0.035mol/L, the prepared BiOI has the best photocatalytic performance, the degradation rate of methyl orange can reach 92.6%. in this experiment in order to obtain flake BiOI photocatalyst with high activity provides a strategy of simple preparation, can for removing the organic pollutant in the wastewater.
(2) under the condition of room temperature, 3D flower like hierarchical structure of BiOI photocatalyst prepared by ethylene glycol assisted hydrolysis method. Characterization and morphology of the samples, BiOI analysis of elements, crystal structure and optical characteristics. The results showed that the concentration of ethylene glycol is the main factor to regulate the morphology of BiOI samples in the visible. Light (2 400nm), flower like structure of BiOI (S10) showed the best photocatalytic activity in degradation of methyl orange in the experiment, consistent change trend and the photocurrent properties corresponding to the first-order rate constant of 0.826h-1.BiOI photocatalytic activity. This experiment provides a useful reference for the preparation of three-dimensional flower BiOI excellent photocatalytic performance.
(3) in two-dimensional sheet and 3D flower like BiOI as the carrier, the Ag/BiOI composite photocatalyst was prepared by photodeposition. Simple BiOI vector describes the influence of two kinds of morphologies on the growth process of Ag QDs and its photocatalytic activity of Ag/BiOI. In the light of the deposition process, two-dimensional sheet carrier BiOI has weak the separation efficiency, promote the generation of larger size Ag quantum dots, which leads to the photoinduced electron capture efficiency, the photocatalytic activity was significantly enhanced. In contrast, Ag small quantum dot 3D flowerlike BiOI surface, the photocatalytic activity of Ag/BiOI was lower. The corresponding enhancement in the degradation of methyl orange in the experiment, the pseudo first order rate constant flake like and flower like BiOI were 0.32 and 0.85h-1, respectively. The photocatalytic activity of Ag/BiOI is corresponding to BiOI 3.25 and 1.11 times. In the degradation of phenol, the photocatalytic activity of Ag/BiOI were 1.31 and 1.13 times of the corresponding BiOI. The results show that the regulation of the morphology of the carrier is an effective means to improve the photocatalytic activity of Ag/BiOI and even more precious metal / semiconductor complexes.

【学位授予单位】：淮北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X505;O643.36

【参考文献】

相关期刊论文 前1条

1 Haili Lin;Chunchun Zhou;Jing Cao;Shifu Chen;;Ethylene glycol-assisted synthesis, photoelectrochemical and photocatalytic properties of BiOI microflowers[J];Chinese Science Bulletin;2014年27期

本文编号：1407414