纳米银的可控合成及其催化性能研究
发布时间：2019-01-01 08:02
【摘要】：纳米银作为一种贵金属纳米材料愈来愈备受关注,其具有的与块状金属不同的特殊的化学和物理性质使得其在光化学、电化学、生物医学和工业催化等领域都得到了广泛的应用。然而,纳米银的形貌和尺寸大小与它表现出的各种性能是息息相关的。所以,当今的研究热点之一就是对纳米银的形貌进行可控制备。目前,纳米银在其形貌的可控合成方面取得的成就仍然比较有限。基于此,本文分别利用反相微乳液法和液相化学还原法成功制备了多种形貌的贵金属纳米银粒子,探索出了一种简易的一步合成银纳米线的方法。此方法区别于以往文献中报道的银纳米线合成过程中需慢慢滴加注入反应液这一过程。反应物一次性溶解,无需控制滴加速度,使得操作更加简单易行,适合大规模生产。另外,据文献报道,经过纳米银负载的半导体如ZnO的光学性能,抗菌性能等都有很大的改善,鉴于此,本文又利用光照还原法成功合成了Ag-ZnO的纳米棱柱复合阵列。本论文的研究工作主要内容如下：利用反相微乳液法,以二丁酸二辛酯磺酸钠充当表面活性剂、异辛烷为溶剂自发形成的W/O型微乳液体系中,分别以AgNO3和抗坏血酸为银源和还原剂,制备了尺寸均匀,无任何团聚现象,单分散性非常好的球形纳米银颗粒。用液相化学还原法,将N,N二甲基甲酰胺(DMF)作为溶剂兼还原剂,以聚乙烯吡咯烷酮(PVP)作为表面活性剂,通过调控改变相关实验条件,可控制备了银的三角形、六边形纳米片和十面体混合物,银的六角多面体,六边形纳米银片以及链状和线状Ag的形貌结构。实验结果表明,溶液中AgNO3与PVP的浓度比是决定合成Ag最终形貌的关键。除此之外,为了研究不同的还原剂对合成的银形貌结构的影响,我们用乙二醇(EG)代替DMF作为溶剂和还原剂,通过改变实验条件,同样在油浴锅中以相同的温度还原AgNO3,制备了不同形貌的纳米Ag晶,包括单分散的Ag六角多面体和纳米Ag线。探索出了一种简易的一步合成银纳米线的方法。将上述实验制备的各种形貌的纳米银应用于催化亚甲基蓝的还原实验。结果表明：用液相还原法合成的多形貌纳米银都有很好的催化性能,其中,六角多面体纳米银晶的催化效果最好。进一步探讨了不同银用量对于亚甲基蓝还原效果的影响,以及可能的催化反应机理。而在亚甲基蓝的还原反应实验中,用反相微乳液法合成的纳米银颗粒没有表现出明显的催化性能。以氧化锌纳米柱为载体,用先浸泡吸附后光照还原的方法在氧化锌纳米柱表面均匀负载了银纳米颗粒,成功合成了Ag-ZnO的纳米棱柱复合阵列,此合成方法能准确控制贵金属的沉积量和金属颗粒的大小,且操作简单易行。
[Abstract]:As a kind of precious metal nanomaterials, nano-silver has attracted more and more attention. Its special chemical and physical properties are different from bulk metals, which make it in photochemistry and electrochemistry. Biomedicine and industrial catalysis have been widely used. However, the morphology and size of silver nanoparticles are closely related to their various properties. Therefore, one of the research hotspots is to control the morphology of silver nanoparticles. At present, the achievements of nano-silver in the controllable synthesis of its morphology are still limited. Based on this, silver nanoparticles with various morphologies were successfully prepared by reverse microemulsion method and liquid phase chemical reduction method, and a simple one-step method of silver nanowires synthesis was explored. This method is different from the process of silver nanowires synthesis reported in the past. The reactant dissolved in one-time, without controlling droplet acceleration, makes the operation easier and more suitable for mass production. In addition, it has been reported that the optical properties and antibacterial properties of nano-silver supported semiconductors such as ZnO have been greatly improved. In view of this, we have successfully synthesized the nano-prism composite arrays of Ag-ZnO by the method of light reduction. The main contents of this thesis are as follows: in the W / O microemulsion system, sodium dioctyl dibutyrate was used as surfactant and isooctane as solvent by reverse microemulsion method. Using AgNO3 and ascorbic acid as silver source and reducing agent, spherical silver nanoparticles with uniform size, no agglomeration and very good monodispersity were prepared. The triangulation of silver can be controlled by changing the experimental conditions by liquid phase chemical reduction method, using N-dimethylformamide (DMF) as solvent and reductant, polyvinylpyrrolidone (PVP) as surfactant. The morphology and structure of hexagonal and decahedron, hexagonal polyhedron, hexagonal silver sheet and chain and linear Ag. The experimental results show that the concentration ratio of AgNO3 to PVP is the key to determine the final morphology of synthesized Ag. In addition, in order to study the effect of different reductants on the morphology and structure of synthesized silver, we used ethylene glycol (EG) instead of DMF as solvent and reductant. By changing the experimental conditions, we also reduced AgNO3, at the same temperature in oil bath pot. Nanocrystalline Ag crystals with different morphologies were prepared, including monodisperse Ag hexagonal polyhedrons and nanocrystalline Ag wires. A simple one-step method for the synthesis of silver nanowires has been developed. The nano-silver with various morphologies was used to catalyze the reduction of methylene blue. The results show that the polymorphic nanocrystalline silver synthesized by liquid phase reduction method has good catalytic performance, among which hexagonal polyhedron nanocrystalline has the best catalytic effect. The effect of different amount of silver on the reduction of methylene blue and the possible mechanism of catalytic reaction were discussed. However, in the reduction experiment of methylene blue, the silver nanoparticles synthesized by inverse microemulsion method showed no obvious catalytic activity. Silver nanoparticles were uniformly loaded on the surface of zinc oxide nanocrystals by immersion adsorption and light reduction method, and Ag-ZnO nano-prism composite arrays were successfully synthesized. This synthetic method can accurately control the deposition amount of precious metals and the size of metal particles, and is easy to operate.
【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O614.122;TB383.1
本文编号：2397241
[Abstract]:As a kind of precious metal nanomaterials, nano-silver has attracted more and more attention. Its special chemical and physical properties are different from bulk metals, which make it in photochemistry and electrochemistry. Biomedicine and industrial catalysis have been widely used. However, the morphology and size of silver nanoparticles are closely related to their various properties. Therefore, one of the research hotspots is to control the morphology of silver nanoparticles. At present, the achievements of nano-silver in the controllable synthesis of its morphology are still limited. Based on this, silver nanoparticles with various morphologies were successfully prepared by reverse microemulsion method and liquid phase chemical reduction method, and a simple one-step method of silver nanowires synthesis was explored. This method is different from the process of silver nanowires synthesis reported in the past. The reactant dissolved in one-time, without controlling droplet acceleration, makes the operation easier and more suitable for mass production. In addition, it has been reported that the optical properties and antibacterial properties of nano-silver supported semiconductors such as ZnO have been greatly improved. In view of this, we have successfully synthesized the nano-prism composite arrays of Ag-ZnO by the method of light reduction. The main contents of this thesis are as follows: in the W / O microemulsion system, sodium dioctyl dibutyrate was used as surfactant and isooctane as solvent by reverse microemulsion method. Using AgNO3 and ascorbic acid as silver source and reducing agent, spherical silver nanoparticles with uniform size, no agglomeration and very good monodispersity were prepared. The triangulation of silver can be controlled by changing the experimental conditions by liquid phase chemical reduction method, using N-dimethylformamide (DMF) as solvent and reductant, polyvinylpyrrolidone (PVP) as surfactant. The morphology and structure of hexagonal and decahedron, hexagonal polyhedron, hexagonal silver sheet and chain and linear Ag. The experimental results show that the concentration ratio of AgNO3 to PVP is the key to determine the final morphology of synthesized Ag. In addition, in order to study the effect of different reductants on the morphology and structure of synthesized silver, we used ethylene glycol (EG) instead of DMF as solvent and reductant. By changing the experimental conditions, we also reduced AgNO3, at the same temperature in oil bath pot. Nanocrystalline Ag crystals with different morphologies were prepared, including monodisperse Ag hexagonal polyhedrons and nanocrystalline Ag wires. A simple one-step method for the synthesis of silver nanowires has been developed. The nano-silver with various morphologies was used to catalyze the reduction of methylene blue. The results show that the polymorphic nanocrystalline silver synthesized by liquid phase reduction method has good catalytic performance, among which hexagonal polyhedron nanocrystalline has the best catalytic effect. The effect of different amount of silver on the reduction of methylene blue and the possible mechanism of catalytic reaction were discussed. However, in the reduction experiment of methylene blue, the silver nanoparticles synthesized by inverse microemulsion method showed no obvious catalytic activity. Silver nanoparticles were uniformly loaded on the surface of zinc oxide nanocrystals by immersion adsorption and light reduction method, and Ag-ZnO nano-prism composite arrays were successfully synthesized. This synthetic method can accurately control the deposition amount of precious metals and the size of metal particles, and is easy to operate.
【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O614.122;TB383.1
【参考文献】
相关期刊论文 前4条
1 井立强,蔡伟民,孙晓君,侯海鸽,徐自力,杜尧国;Pd/ZnO和Ag/ZnO复合纳米粒子的制备、表征及光催化活性[J];催化学报;2002年04期
2 邵忠宝,王成艳,陈雪冰,韩春梅,王颖;纳米ZnO/Ag的制备及其光催化性能[J];材料研究学报;2005年01期
3 高燕红;张念椿;冯炫;刘应亮;;晶种法制备单分散的金纳米粒子及光学性能研究[J];贵金属;2010年04期
4 罗阳明,孙颖,王昌斌,韩军;纳米Pt粒子的微乳液法制备研究[J];功能材料;2002年06期
，本文编号：2397241
本文链接：https://www.wllwen.com/kejilunwen/cailiaohuaxuelunwen/2397241.html
