二氧化硅纳米颗粒的功能化改性及应用研究

发布时间：2018-04-12 07:00

本文选题：表面改性 + 复合纳米结构　；参考：《济南大学》2015年硕士论文

【摘要】：纳米材料的尺寸及形貌与其性能密切相关,本文通过对反应参数的精确控制,在改性二氧化硅纳米颗粒的基础之上制备了多种复合纳米材料,并对复合纳米材料的形貌及性能进行了研究,证明了此类复合材料在催化及光催化领域具有广阔的应用前景。主要内容及结果如下:1.制备粒度分布均匀的二氧化硅纳米颗粒并对其进行表面改性。用氨水、水、乙醇、正硅酸四乙酯作为反应体系,通过对各种原料用量的精确控制,制备了粒径均匀尺寸在100 nm左右的二氧化硅纳米颗粒。利用合适摩尔比的3-巯丙基三乙氧基硅烷对二氧化硅纳米颗粒进行表面改性,利用水解及缩合反应,将二氧化硅纳米颗粒表面均匀修饰了一层巯基官能团。2.制备SiO2@Ag、SiO2@Au、Si O2@Fe3O4复合纳米材料。以表面改性的二氧化硅纳米颗粒作为基底,在上面均匀的沉积银、金及四氧化三铁纳米颗粒,表面改性是制备此类复合纳米结构的关键因素。金与银贵金属纳米颗粒是通过硼氢化钠的还原作用制备的,四氧化三铁纳米颗粒是通过共沉淀法在氨水的参与下合成的。此制备方法简单灵巧,制备出的复合纳米结构形貌可控,并且表面的纳米颗粒分散均匀、粒径可控且与基底二氧化硅连接的牢固性高。3.Au催化剂与SiO2@Au催化剂的性能研究。实验制备了5 nm和10 nm两种不同粒径的Au催化剂,然后制备了两种不同基底比例的SiO2@Au催化剂。结果证明,SiO2@Au比Au催化剂表现出了更高的催化活性,合适的基底量是SiO2@Au催化剂保持高催化活性的关键。这是因为,基底的存在可以获得没有表面配体的小尺寸的Au纳米颗粒,高的表面能及界面能使其具有高的催化活性,并且该复合结构在循环催化实验中表现出高的稳定性和活性。4.合成SiO2@AgCl及SiO2@Ag3PO4复合纳米结构,并研究其在紫外光下对罗丹明B的光催化降解性能。先将SiO2@Ag表面的Ag纳米颗粒进行生长,使其尺寸增大,再利用具有大尺寸Ag纳米颗粒的SiO2@Ag复合结构来制备SiO2@AgCl和SiO2@Ag3PO4光催化剂,此方法是一种值得研究的方法。实验证明,此类催化材料在紫外光照射下具备优异的光催化性能,且SiO2@Ag3PO4比Si O2@AgCl的光催化性能优异。5.合成单核或多核的两种不同结构的Ag@SiO2复合纳米结构。运用单宁酸做还原剂制备Ag与Au纳米颗粒,调控反应体系的pH值,各获得了两种不同尺寸的Ag纳米颗粒与Au纳米颗粒。由于Ag纳米颗粒尺寸随反应体系pH值的敏感性,我们利用Ag进行了二氧化硅组装,通过反应过程中添加正硅酸乙酯步骤的精确调控,制备了单核和多核两种不同形貌的复合结构。并且利用L-精氨酸对丹宁酸修饰的银纳米颗粒进行了表面改性及二氧化硅的包覆。
[Abstract]:The size and morphology of nanomaterials are closely related to their properties. In this paper, a variety of composite nanomaterials were prepared on the basis of modified silica nanoparticles by precise control of reaction parameters.The morphology and properties of the composite nano-materials were studied. It is proved that the composite has a broad application prospect in the field of catalysis and photocatalysis.The main contents and results are as follows: 1.Silica nanoparticles with uniform particle size distribution were prepared and modified on the surface.Using ammonia, water, ethanol and tetraethyl orthosilicate as reaction system, silica nanoparticles with uniform size of about 100nm were prepared by controlling the amount of raw materials.Silica nanoparticles were modified with 3-mercaptopropyl triethoxy silane in a suitable molar ratio. The surface of silica nanoparticles was uniformly modified with a thiol functional group by hydrolysis and condensation.SiO _ 2 and Sio _ 2 O2@Fe3O4 composite nanomaterials were prepared.The surface modification of silica nanoparticles on which silver, gold and iron trioxide nanoparticles were uniformly deposited was the key factor for the preparation of such composite nanostructures.Gold and silver noble metal nanoparticles were prepared by the reduction of sodium borohydride, and Fe _ 2O _ 4 nanoparticles were synthesized by co-precipitation with the participation of ammonia water.The preparation method is simple and dexterous, the morphology of the composite nanostructure is controllable, and the surface nanoparticles are uniformly dispersed, the particle size is controlled and the stability of the catalyst to the substrate silica is high. 3. The performance of au catalyst and SiO2@Au catalyst is studied.Two kinds of au catalysts with different diameters of 5 nm and 10 nm were prepared, and then two kinds of SiO2@Au catalysts with different substrates were prepared.The results show that the SiO2O2O- OU catalyst exhibits higher catalytic activity than au catalyst, and the key to maintain the high catalytic activity of the SiO2@Au catalyst is the appropriate amount of substrate.This is because the existence of the substrate can obtain small size au nanoparticles without surface ligands, and the high surface energy and interface can make them have high catalytic activity.Moreover, the composite structure showed high stability and activity in cyclic catalytic experiments.The composite nanostructures of SiO2@AgCl and SiO2@Ag3PO4 were synthesized and their photocatalytic degradation of Rhodamine B under ultraviolet light was studied.The Ag nanoparticles on the surface of SiO2@Ag were grown to increase their size, and then the SiO2@AgCl and SiO2@Ag3PO4 photocatalysts were prepared by using the SiO2@Ag composite structure with large Ag nanoparticles. This method is worth studying.The experimental results show that this kind of catalyst has excellent photocatalytic performance under ultraviolet irradiation, and the photocatalytic performance of SiO2@Ag3PO4 is better than that of Si O2@AgCl.Ag@SiO2 nanostructures with two different mononuclear or polynuclear structures were synthesized.Silver and au nanoparticles were prepared by using tannic acid as reducing agent. Two kinds of Ag nanoparticles and au nanoparticles with different sizes were obtained by adjusting the pH value of the reaction system.Due to the sensitivity of the size of Ag nanoparticles to the pH value of the reaction system, the silica was assembled with Ag, and the step of adding ethyl orthosilicate to the reaction process was accurately regulated.Mononuclear and multicore composite structures with different morphologies were prepared.The silver nanoparticles modified by tannin were modified by L-arginine and coated with silica.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.2;TB383.1

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