钼酸铋基纳米材料的制备及其在光催化中的应用

发布时间：2017-12-31 15:01

  本文关键词：钼酸铋基纳米材料的制备及其在光催化中的应用　出处：《华东师范大学》2017年博士论文　论文类型：学位论文

  更多相关文章： 光催化 可见光 钼酸铋 复合物 异质结

【摘要】：随着人口的增加以及工业化和城市化的加速,各种有机废水被大量排放,这严重影响了人类的身体健康以及地球的生态平衡。因此,治理和控制水体污染成为了环境领域亟需解决的问题。由于光催化技术具有氧化能力强,无二次污染,能耗低,催化剂可以重复利用,反应条件相对温和且易于操作等优点,因此,从环境保护与能源利用方面考虑,光催化技术具有巨大的应用前景。目前,科研工作者对光催化的研究主要集中在两个方面:一个是对常用的TiO2,SnO2与ZnO等宽带隙半导体进行改性,使其光响应范围拓展至可见光区域;另一种是寻找可响应可见光的新型半导体光催化剂,包括一些对可见光响应的氧化物,硫化物等。钼酸铋作为一种铋基Aurivillius氧化物半导体,由于其具有独特的层状结构、良好的光学性能以及优异的催化活性,成为了目前光催化领域的一个研究热点。本论文旨在通过溶剂热法探索钼酸铋的结构对其光催化性能的影响,并通过进一步对钼酸铋进行改性,以获得更高的光催化性能。本论文主要是围绕着钼酸铋基纳米材料的优化进行研究,通过对其结构与复合物进行优化设计,提高其光催化性能。主要研究内容如下:1.通过对溶剂热温度的优化,发现合适的温度可使Bi2Mo06形成蛋黄-壳(yolk-shell)结构。同时,也对yolk-shell结构Bi2MoO6的形成过程展开分析,发现其无模板形成yolk-shell结构主要是由于Ostwald熟化过程形成。在与纳米片结构和纳米颗粒结构Bi2MoO6的光催化性能对比发现,yolk-shell结构Bi2MoO6展现出更为优异的光催化性能,其对罗丹明B(Rhodamine B,RhB)的光催化降解在240 min内可达97%。这种优秀的光催化性能主要归咎于yolk-shell结构产生的多次光漫反射,从而提高了其对光的捕获能力。2.对碳纳米管(Carbon Nanotube,CNT)与碳球(Carbon Sphere,CS)进行酸化使其表面带有一定的负电荷。在溶剂热的过程中,由于碳材料表面负电荷产生的弱电场作用,Bi2MoO6在CNT或CS周围迅速成核生长,分别形成交联结构Bi2Mo06-CNT复合物或者核-壳(core-shell)结构CS@Bi2Mo06复合物。随着CNT与CS的引入,Bi2MoO6-CNT与CS@Bi2MoO6复合物的光催化性能与Bi2MoO6相比得到改善,这是由于交联结构复合物以及core-shell结构CS@Bi2MoO6复合物在光照射下电子可快速转移,从而达到降低光生-电子空穴对的复合的目的。优化后交联结构Bi2MoO6-CNT复合物在120 min内对RhB的降解率在89%。而对于优化后的core-shell结构CS@Bi2MoO6复合物,其在120 min内其对RhB的降解率在95%。3.将Bi4-2xMoxO6(x≤1)中Bi与Mo的比例进行优化,设计出yolk-shell结构的Bi2.38Mo0.81O6微球。由于Bi2.38Mo0.81O6微球中存在大量的缺陷,因此在光催化过程中产生大量的载流子可以被这些缺陷收集以及转移,从而提高其光催化性能。其中,Bi2.38Mo0.81O6展现出最佳的光催化性能,在120min内其对RhB的降解率为99%。再利用GO包裹于Bi2.38Mo0.81O6微球表面,在微波照射下对GO进行还原,可得到BMO@RGO复合物。由于RGO具有良好的电子传输性能,且Bi2.38Mo0.81O6与RGO具有良好的接触以及阶梯能级的存在,因此,在光催化过程中其光生载流子可迅速转移,从而达到降低光生-电子空穴对的复合的目的,最终实现其光催化性能的提高。优化过的Bi2.38Mo0.81O6@RGO复合物在80 min内对RhB的降解率为99%。4.在Bi2MoO6前驱中加入SnO2与TiO2,可制备出Bi2MoO6-SnO2与Bi2MoO6-TiO2异质结。由于SnO2与TiO2的存在,Bi2MoO6在SnO2或TiO2周围迅速成核及生长,形成异质结。由于异质结的形成,Bi2MoO6-SnO2与Bi2MoO6-TiO2异质结的光催化性能均得到比较大的改善。这是由于异质结中存在阶梯能级结构,这种阶梯能级结构有利于光生电子的迅速转移,从而有利于光催化性能的改善。其中,优化后的Bi2MoO6-SnO2异质结复合物在150min内其对RhB的降解率为97%以及在360 min内其对硝基苯的降解率为90%。而对于优化后的Bi2MoO6-TiO2异质结复合物,其在300 min内其对苯酚与硝基苯的降解率分别为96%与94%。
[Abstract]:With the increase of population and the acceleration of industrialization and city, all kinds of organic wastewater is discharged, which seriously affected the health of human beings and the earth's ecological balance. Therefore, governance and control of water pollution has become the urgent environmental problem. The photocatalytic technology has strong oxidation ability, no two pollution. Low energy consumption, the catalyst can be reused, relatively mild reaction conditions and easy operation etc., therefore, considering the protection and utilization of energy environment, photocatalytic technology has great application prospect. At present, the research of scientific research workers of photocatalysis mainly concentrated in two aspects: one is the commonly used TiO2, broadband SnO2 and ZnO semiconductor gap was modified to expand the range to the visible light response; the other is to seek new semiconductor photocatalyst in response to visible light, including some of the See the light response of oxides, sulfides. Bismuth molybdate as a bismuth based oxide semiconductor Aurivillius, due to its unique layered structure, good optical properties and excellent catalytic activity, has become a hot research topic in photocatalysis field at present. This paper aims at exploring the structure by solvothermal method of bismuth molybdate on the photocatalytic properties of bismuth molybdate, and through further modification to obtain higher photocatalytic performance. This paper is mainly around the optimization of bismuth molybdate based nano materials was studied, through the optimization design on its structure and composite, improve the photocatalytic performance. The main contents are as follows: 1. through the optimization of the solvent temperature, find the suitable temperature can make the formation of Bi2Mo06 yolk shell (yolk-shell) structure. At the same time, also the formation process of yolk-shell structure Bi2MoO6 expansion analysis, found the No template to form the yolk-shell structure is mainly due to the formation of Ostwald ripening process. In contrast the photocatalytic properties of nano particles and nano structure and Bi2MoO6 structure, yolk-shell structure Bi2MoO6 showed more excellent photocatalytic properties, the Luo Danming B (Rhodamine B RhB) multiple light diffuse reflection of the photocatalytic degradation of up to 240 min 97%. this excellent photocatalytic performance is mainly attributed to the yolk-shell structure, thereby improving the light harvesting ability of.2. on carbon nanotubes (Carbon Nanotube, CNT) and carbon (Carbon Sphere, CS) ball in acidified with a negative charge on the surface. In certain solvothermal process. Due to the weak electric field produced by carbon material surface negative charge, Bi2MoO6 around CNT or CS rapid nucleation and growth, the formation of crosslinked Bi2Mo06-CNT complexes or core-shell structure were (core-shell) CS@Bi2Mo06 complex With the introduction of CNT and CS. The photocatalytic properties of Bi2MoO6 and Bi2MoO6-CNT and CS@Bi2MoO6 composite was improved compared to, this is due to the crosslinking structure of composite structure of CS@Bi2MoO6 and core-shell complexes in the light irradiation electron can quickly transfer, thereby reducing the photogenerated electron hole pairs of composite - purpose. The optimized crosslinking structure of Bi2MoO6-CNT complexes in 120 min the degradation rate of RhB in 89%. and core-shell for the CS@Bi2MoO6 complex structure after optimization, which in 120 min the degradation rate of RhB in 95%.3. Bi4-2xMoxO6 (x = 1) in Bi and Mo than the optimized design of Bi2.38Mo0.81O6 microspheres, yolk-shell structure due to the presence of. A large number of defects of Bi2.38Mo0.81O6 microspheres, resulting in a large number of carriers can be collected and transfer these defects in the photocatalytic process, so as to improve its photocatalytic performance. Among them, Bi2.38Mo0. 81O6 showed the best photocatalytic performance in the 120min, the RhB degradation rate for 99%. using GO coated on the surface of Bi2.38Mo0.81O6 microspheres under microwave irradiation, in the reduction of GO by BMO@RGO, can be complex. Because RGO has good electrontransport properties, and Bi2.38Mo0.81O6 and RGO have good contact and ladder level the existence, therefore, in the photocatalytic process of the photogenerated carriers can quickly transfer, thereby reducing the photogenerated electron hole pairs of composite - to realize its photocatalytic performance. Bi2.38Mo0.81O6@RGO complexes optimized within 80 min the degradation rate of RhB was 99%.4. SnO2 and TiO2 Bi2MoO6 in addition the precursor, Bi2MoO6-SnO2 can be fabricated with Bi2MoO6-TiO2 heterojunction. Due to SnO2 and TiO2, Bi2MoO6 rapid nucleation and growth of around SnO2 or TiO2, forming a heterojunction. Due to the formation of Bi2Mo heterojunction. O6-SnO2 and Bi2MoO6-TiO2 heterojunction photocatalytic performance have been greatly improved. This is due to the existence of ladder level structure of heterojunction, the ladder level structure is conducive to the rapid transfer of photogenerated electrons, which is conducive to improve the photocatalytic performance. Among them, the Bi2MoO6-SnO2 heterojunction complexes in 150min to RhB the degradation rate was 97% and in 360 min the degradation rate of nitrobenzene was 90%. for optimized Bi2MoO6-TiO2 heterojunction complexes after optimization, the within 300 min of phenol and nitrobenzene degradation rate were 96% and 94%.

【学位授予单位】：华东师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36

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