【作者】 张丹慧；

【导师】 刘孝恒；

【作者基本信息】 南京理工大学 ， 材料材料与工程， 2011， 博士

【摘要】 银纳米粒子具有非常稳定的物理化学性能,因此在光学、催化、电学等众多领域表现出十分优异的特性。目前银纳米粒子仍是研究的热点。本论文以硝酸银为银源,在室温下合成了不同颗粒大小、不同尺寸分布、不同形貌的银纳米粒子,以及不同的含银复合材料,如Ag/ZnO复合物、Ag/GO(氧化石墨烯)复合物。并对合成的银纳米粒子及其复合物的性质、应用进行了研究。主要内容如下：1.采用液-液两相(水相-有机相)法,以十二烷基三甲基溴化铵作为表面活性剂,十二烷基硫醇作为保护剂,硼氢化钠作为还原剂,在室温下合成红棕色的纳米银溶胶。合成的银溶胶存在于有机相中。同时,对合成的银纳米粒子的光学性质进行了研究,发现不同的反应时间、有机溶剂对合成的银纳米粒子的粒径大小及尺寸分布有着较大的影响。反应时间越长,形成的银纳米粒子的粒径越小且尺寸分布越均匀。考察了三种不同的有机溶剂(甲苯、己烷及氯仿)对形成的银纳米粒子的影响,研究发现,在甲苯溶剂中形成的银纳米粒子的粒径较小且分布较窄。同时将合成的银纳米粒子作为催化剂,催化硼氢化钠还原对硝基苯酚合成氨基苯酚的反应。2.在水相-有机相两相体系中,以四正丁基溴化铵作为表面活性剂,十二烷基硫醇作为保护剂,水合肼作为还原剂,在室温下合成规则排列的银超晶格。考察了不同反应时间对银自组装结构的影响,实验结果表明反应时间太短,银纳米粒子不能很好的被十二烷基硫醇所包覆,形成的结构不完美。同时考察了以超晶格银作为催化剂,催化硼氢化钠还原对硝基苯酚的催化活性,结果显示,因形成超晶格银纳米粒子的颗粒非常小仅有3nm左右,因此其催化效果非常显著,其动力学反应常数(Kap)达到21.3×10-3s-1。3.采用液-液两相法,以癸二酸、油酸作为保护剂,十六烷基三甲基溴化铵为表面活性剂,考察了不同条件(如有无保护剂、保护剂的用量、反应时间等一系列条件)对形成的银纳米粒子的形貌、粒径的影响。研究发现,以癸二酸、油酸作为保护剂,形成的银纳米粒子是单分散的,且粒径分布范围比较窄。4.利用生物大分子壳聚糖既作为保护剂又作为还原剂,在室温下绿色合成了五边形、六边形、梯形、三角形等不同形貌的银纳米片。同时,对银纳米片的形成机理、光学性质进行了探讨。另外,以结晶紫为探针,银纳米片作为基底的表面增强拉曼效应(SERS)进行了研究,研究结果发现,其增强因子(EF)为2.6×103。5.在室温下,采用液-液两相法合成了片状的ZnO及ZnO片/Ag纳米复合材料,并对其形成机理进行了研究,同时考察了其作为催化剂,光催化降解甲基橙染料的催化活性。结果发现,形成的ZnO为片状,在高能电子束下不稳定,但当银纳米粒子负载在ZnO表面后,使得ZnO的稳定性显著增强,同时研究发现ZnO/Ag纳米复合材料的光催化活性明显的优于单纯的ZnO纳米材料。6.利用明胶既作为保护剂又作为还原剂,在室温下绿色合成了棱镜形的银纳米粒子,并将其负载在氧化石墨烯(GO)的表面上,形成Ag/GO复合材料。并对复合物的形貌、形成机理、抗菌活性进行了探讨。研究结果发现,合成的银纳米粒子为棱镜形状且负载在氧化石墨烯的褶皱处。同时,Ag/GO复合材料表现出较好的抗菌效果。更多还原

【Abstract】 Silver nanoparticles, due to its specific physical and chemical properties, show excellent characteristics in the optical, catalytic, electrical and many other fields. At present, the silver nanoparticles are still the research focus. The research of this thesis focuses on the synthesis, properties and potential application of silver nanoparticles and their composites such as Ag/ZnO and Ag/GO. The principal results of the dissertation are discussed as follows:1. Silver nanoparticles, which were produced by the sodium borohydride reduction of silver nitrate, were stabilized by means of 1-dodecanethiol providing sulfur atom. (n-dodecyl)trimethylammonium bromide (DTAB) which was used as phase transfer agent in two-phase system involving water and toluene played an significant role in the formation of monolayer-protected silver nanoparticles. It was also found that different organic solvent played major role in the particle size of silver nanoparticles. The results indicate that the particles size of silver nanoparticles were quite different under the three kind of condition. Furthermore,1-dodecanethiol-capped silver nanoparticles are found to serve as effective catalysts to activate the reduction of 4-nitrophenol (4NP) in the presence of NaBH4, where the size of silver nanoparticles is found to play the determining role on catalytic activity.2. Superlattice of silver nanoparticles were prepared using a liquid-liquid two-phase method with hydrazine hydrate (N2H4·H2O), tetra-n-butylammonium bromide ((C4H9)4NBr) and 1-dodecanethiol as reducing agent, phase transfer agent and stabilized agent, respectively. The reaction time plays a major role in the formation of superlattice of silver nanoparticles. Furthermore, the superlattice of silver nanoparticles are found to serve as effective catalysts to activate the reduction of 4-nitrophenol (4NP) in the presence of NaBH4. The results indicate that the formed silver nanoparticles are so small, only about 3 nm, but they have a high catalytic activity, the kinetic reaction rate constant (defined as Kap) of which reaches to 21.3×10-3s-1.3. The size-controlled synthesis of silver nanoparticles were prepared in a cetyl trimethyl ammonium bromide (CTAB)/toluene reverse micelle system using oleic acid or sebacic acid as stabilizing agents. The formation of silver nanoparticles was influenced by factors such as reaction time, concentration of CTAB, the quantity of fatty acid and so on. It can be seen that the formed silver nanoparticles are monodispersed with a narrow size distribution.4. Single-crystal silver slices with different shapes such as hexagon, trapezium, triangle were synthesized at room temperature with chitosan by a facile, one-pot, and totally green method. The results showed that chitosan, a novel environmentally benign and excellently biocompatible material, serves not only as a reducing agent but also as a stabilizer for the growth of anisotropic silver nanoparticles. The single-crystal silver slices with major facet of (111) can be used as a surface-enhanced Raman scattering (SERS) substrate, and crystal violet (CV) as a Raman probe to evaluate its enhancement ability. It was found that the enhancement ability of the silver slices was remarkable and enhancement factor(EF) reached to 2.6×103.5. The Ag nanoparticles-stabilized ZnO nanosheets were prepared using a liquid-liquid two-phase method with (n-dodecyl)trimethylammonium bromide (DTAB) as a phase transfer agent at the room temperature. The results demonstrate that the silver nanoparticles load on the surface of ZnO sheets and make the ZnO sheets stabilize. Furthermore, the formation mechanism of ZnO sheets stabilized by silver nanoparticles was also proposed and discussed in detail. Moreover, the photocatalysis test shows that the ZnO sheets stabilized by silver nanoparticles exhibit a higher photocatalytic activity than the pure ZnO nanosheets.6. A widely soluble graphene oxide sheets decorated by silver nanoprisms were prepared through green synthesis at the room temperature using gelatin as reducing and stabilizing agent. The results demonstrate that these silver-nanoprisms assembled on graphene oxide sheets are flexible and can form stable suspensions in aqueous solutions. Furthermore, the formation mechanism of soluble graphene oxide sheets decorated by silver nanoprisms was successfully explained. The anti-bacterial properties of graphene oxide sheets decorated by silver nanoprisms were tested against Escherichia coli.更多还原