【作者】 史玉立；

【导师】 邹竞； 王虹；

【作者基本信息】 天津大学 ， 化学工艺， 2010， 博士

【摘要】 纳米材料是21世纪的研究热点。金属纳米材料因其独特的物理化学性质而引起研究者的广泛关注。其中,贵金属纳米材料在电子学、光学、催化、传感、生物标记以及光电纳米器件等众多领域具有良好的应用前景,成为国内外研究开发的重点。选择合适的保护剂,有效控制晶体的各向异性生长是制备不同形貌和尺寸纳米材料的关键。目前,研究者不断开发出简单、可靠、节约成本的新方法,旨在推动纳米材料的大规模生产。其中,化学还原法是一种具有良好发展前景的制备贵金属纳米材料的方法。本文采用化学还原法,在有机和水相体系中得到了不同形貌、尺寸的贵金属银、金及其合金纳米颗粒。并利用透射电子显微镜(TEM)、高倍透射电子显微镜(HR-TEM)、X-射线衍射(XRD)、电子选区衍射(SAED)、紫外-可见光谱(UV-Vis)等测试手段对其进行表征。首先,我们利用有机溶剂,表面活性剂司班80和银的前驱物硝酸银构成微乳液体系来制备银纳米颗粒。考察了有机溶剂种类和组成,还原剂和硝酸银浓度、比例,反应温度等条件对实验结果的影响。经过优化实验条件,最终得到环己醇-环己酮溶剂体系制备单分散银纳米颗粒的最佳条件为:环己醇和环己酮加入量分别为18 ml,12 ml,司班80加入量为3 ml,2, 2′-亚甲基双-(4-甲基-6-叔丁基苯酚)为0.09 g,硝酸银的水溶液为0.3 ml(0.058 M),反应温度为80°C,反应时间为4 h。在水相体系中,我们采用羧甲基纤维素钠(CMC)兼做保护剂和还原剂,分别制备得到了银、金纳米颗粒。在制备银纳米颗粒过程中,考察了CMC和硝酸银含量及二者比例,反应温度等条件对所得银纳米粒子尺寸、形貌和光学性能的影响。最终得到CMC体系中制备单分散银纳米颗粒的优化条件为:去离子水20 ml,CMC含量0.06 wt%,氢氧化钠(0.1 M)加入量0.5 ml,硝酸银(0.2 M)加入量为0.1 ml,反应温度为80°C,反应时间4 h。利用无机磷酸盐做保护剂制备贵金属纳米颗粒的方法未见文献报道。在水相体系中,我们首次使用磷酸钠、三聚磷酸钠(Sodium tripolyphosphate, STPP)和六偏磷酸钠(Sodium Hexametaphosphate, SHMP)做保护剂,制备了银、金及其合金纳米颗粒。在STPP体系中,可以制备得到不同形貌、尺寸的银纳米颗粒。通过对实验条件的考察,制备得到了大量的棒状银纳米颗粒,通过各种表征手段,我们研究了银纳米棒的生长机理,结果表明:STPP作为线性分子,在水溶液中起到纳米棒生长的模板作用,引起银纳米颗粒的各向异性生长;银纳米颗粒主要沿着晶体的(111)面缓慢生长,并最终形成棒状结构。此外,STPP体系同样可以制备得到粒径均匀的金和金-银合金纳米颗粒。聚丙烯酸钠(PAAS)是一种生物相容性良好的高分子化合物,利用其做保护剂,首次制备得到了片状银纳米颗粒。考察了PAAS浓度,葡萄糖和硝酸银浓度及二者比例,反应温度等条件对实验结果的影响,制备得到了粒径均一的球形银纳米颗粒以及三角形、五边形、六边形片状银纳米颗粒。更多还原

【Abstract】 Nanomaterials have been the hot spot of research in the 21th century. Due to the special physicochemical properties, metal nanomaterials have attracted much attention in the past decades. Among them, noble metal nanomaterials, which possess promising potential application prospect in electronics, optics, catalysis, sensing, biolabeling and optoelectronics, have become important research area both at home and abroad. Precise control of anisotropic crystal growth by capping agents is the key to these excellent works. On the other hand, attempts have been made to develop facile, reliable and cost-effective synthetic strategies in order to enhance efficiency and realize mass production. Chemical reduction method is demonstrated to be a promising way for the synthesis of noble metal nanopartilces (NPs).In this paper, noble metal Ag, Au and Au-Ag alloy nanomaterials with different morphologies and sizes were prepared by chemical reduction method in organic and aqueous systems. And their properties have been characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), high-resolution tranmission electron micorscopy(HR-TEM), selected-area electron diffraction(SAED), ultraviolet-visiable spectrophotometer (UV-Vis) and so on.Firstly, a new micro-emulsion system composed of organic solvents, span 80 as surfactant and silver nitrate aqueous solution as the precursor, was conducted to prepare Ag nanomaterials. The effects of reaction parameters, including solvents composition, the concentrations and ratios of silver nitrate and the reducing agent, were investigated. In addition, the reaction temperatures were also considered. Based on the results of experiments discussed, the reaction conditions for preparing monodisperse Ag NPs in the system of cyclohexanol-cyclohexanone were optimized as follows: tha adding amount of cyclohexanol was 18 ml, cyclohexanone 12 ml, Span 80 3 ml, 2,2’-Methylenebis(6-tert-butyl-4-methylphenol) 0.09g, AgNO3 solution (0.058 M) 0.3 ml, reaction temperature was 80°C, and the reaction time was 4 h.In sodium carboxymethyl cellulose(CMC) aqueous solution system, Ag and Au nanomaterials were prepared with CMC employed as both stabilizer and reducing agent. Based on the size, morphology and optical properties of the obtained nanopartilces, the effects of concentrations and ratios of CMC and AgNO3, temperature and reaction time were discussed. Finally, the optimum condition of preparing monodisperse silver nanoparticles in CMC system was aquired as follows: the adding amount of deioned water was 20 ml, CMC 0.012 g, NaOH aqueous solution(0.1 M) 0.5 ml, AgNO3 solution (0.2 M) 0.1 ml, reaction temperature was 80°C, and the reaction time was 4 h.It has not been reported about the method of preparing noble metal nanomaterials with inorganic phosphate as capping agent. Ag, Au and Au-Ag alloy nanomaterials were first prepared in the phosphate-stablized system. In sodium tripolyphosphate (STPP) aqueous system, silver nanomaterials with different morphologies and sizes were obtained. Through adjustments of reaction conditions, a large number of silver nanorods have been successfully synthesized. Based on the characterization results, a possible formation mechanism has been discussed. It suggests that the preferential direction for the growth of silver nanorods is along with the plane (111). It is therefore reasonable to speculate that the linear structure of STPP and the fairly slow reaction rate are both the key factors in the formation of rod-shaped silver nanoparticles. In addition, Au and Au-Ag alloy nanoparticles with narrow size distribution were also obtained in the STPP system.Polyacrylate acid sodium (PAAS), a polymer with excellent biocompatibility, was used as the capping agent to produce silver nanoplates for the first time. A large number of triangle silver nanoplates were first prepared. The effects of reaction parameters, including the concentration of PASS, concentration and ratio of glucose and AgNO3, reaction temperature, were discussed. The results showed that triangle, pentagon and hexagon silver nanoplates were prepared.更多还原