多价主客结合方法构建可修复的催化基板

发布时间：2018-07-06 13:09

本文选题：多价主客结合 + 金纳米粒子　；参考：《北京化工大学》2017年硕士论文

【摘要】：金纳米粒子(AuNPs)由于具有其优异的催化性能、与粒子尺寸相关的光学性能、良好的生物相容性以及较高的消光系数等而被广泛的研究,特别是其催化性能的应用已涉及化学工业领域。但是作为贵金属,其重复应用也是颇受关注的,因此近几年所提出的重复应用方法也越来越多,但多是在溶液中转移或者循环分散与团聚等,并不是真正意义上的回收。所以目前也有很多科学家集中在AuNPs的回收方面,方法多种多样,包括磁性回收、离心分离等,无论是哪种方法,都需要与其它物质结合,而且结合后的复合体在应用时以及回收后都不可分离,重复利用前都需要经过清洗和干燥过程,这种批处理模式耗时耗力耗资。为满足工业中高效、节约的需求,值得一提的是将AuNPs固定到多孔基材上或者是丝状物质上,这样可以通过过滤的方式实现持续催化的效果,但是其不可修复性限制了其应用。基于以上问题,本实验借助β-环糊精(β-CD)和偶氮苯(Azo)多价主客结合作用的高强度以及其光响应性,制备了 AuNPs功能化的催化基板。前人实验中所固定的AuNPs与基材不可分离,这样会在一定程度上限制AuNPs功能的发挥。所以在实验的第一部分,一方面制备了直径为17.27 nm的AuNPs,通过S-Au键在其表面包覆一层Azo分子。另一方面,通过层层功能化将改性的β-CD结合到镍泡沫(PNi)基板上,再在多价主客结合力的作用下将Azo包覆的AuNPs固定在β-CD功能化的PNi上,在紫外灯的照射下Azo与β-CD的主客结合失效,AuNPs被释放下来,相反,当用可见光照射时,AuNPs可被重新固定到PNi上,实现了 AuNPs的按需释放和回收。由于Azo分子的异构化存在空间位阻效应,因此其在AuNPs表面的结合数量有限,无法通过多价主客结合作用将17.27 nm的AuNPs大量的固定于表面,影响AuNPs功能化表面的应用,所以第二部分实验制备了表面含β-CD的AuNPs,其平均粒径仅仅3.27 nm,同样利用多价主客结合作用将其固定在Azo功能化的PNi表面,所得基底可直接用做4-硝基苯酚还原过程的催化剂,催化效率高于95%,另外,当把剪碎的基底填塞到针管中可制得催化效率接近95%的“催化床”。一旦表面的AuNPs失效,根据第一部分实验中的按需释放机理,还可实现“催化床”的原位修复,极大的符合了工业需求。
[Abstract]:Gold nanoparticles (AuNPs) have been widely studied because of their excellent catalytic properties, optical properties related to particle size, good biocompatibility and high extinction coefficient. In particular, the application of its catalytic performance has been related to the chemical industry. However, as precious metals, its repeated application is also very concerned, so in recent years, more and more repeated application methods have been put forward, but most of them are transferred in solution, dispersed in circulation and agglomerated, and are not really recycled. So at present, there are many scientists who concentrate on the recovery of AuNPs. There are a variety of methods, including magnetic recovery, centrifugal separation, and so on. Either way, it needs to be combined with other substances. The combined complex can not be separated when it is used or recovered. It needs cleaning and drying process before reuse. This batch treatment model is time-consuming and costly. In order to meet the needs of high efficiency and economy in industry, it is worth mentioning that AuNPs are immobilized on porous substrates or filamentous materials, which can achieve the effect of continuous catalysis by filtration, but its application is limited by irreparability. Based on the above problems, AuNPs functional catalytic substrate was prepared by using the high intensity of 尾 -cyclodextrin (尾 -CD) binding with azobenzene (Azo) multivalent host and guest interaction and its photoresponsiveness. The fixed AuNPs in previous experiments can not be separated from the substrate, which limits the function of AuNPs to some extent. In the first part of the experiment, on the one hand, the AuNPs with a diameter of 17.27 nm were prepared, and a layer of Azo molecules was coated on the surface by S-Au bond. On the other hand, the modified 尾 -CD was bonded to the nickel foam (PNi) substrate by layer functionalization, and then the Azo coated AuNPs were immobilized on the 尾 -CD functionalized PNi under the action of multivalent host and guest binding force. ANPs of Azo and 尾 -CD were released under UV irradiation. On the contrary, when irradiated with visible light, ANPs could be reimmobilized to PNi, thus realizing the on-demand release and recovery of AuNPs. Because the isomerization of Azo molecule has steric resistance effect, its binding quantity on the surface of AuNPs is limited, so it is unable to immobilize a large amount of 17.27nm AuNPs on the surface through multivalent host and guest binding, which affects the application of the functionalized surface of AuNPs. In the second part, AuNPs with 尾 -CD on the surface were prepared. The average particle size of AuNPs was only 3.27 nm. It was also immobilized on the surface of Azo functionalized PNi by multivalent host and guest binding. The obtained substrate could be directly used as catalyst for the reduction of 4-nitrophenol. The catalytic efficiency is higher than 95%, in addition, when the shredded substrate is filled in the needle tube, the catalytic efficiency can be nearly 95% of the "catalytic bed". Once the surface AuNPs fail, according to the mechanism of on-demand release in the first part of the experiment, the in-situ repair of "catalytic bed" can be realized, which greatly meets the industrial demand.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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