【作者】 李磊；

【导师】 赵爱武；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2016， 硕士

【摘要】 这些年来,在纳米科技快速发展的大趋势下,各种铁氧化物纳米材料不断的被人们制备出来,并且由于它们所具有的一些独特的性质而被广泛应用于相应的科学研究中。在此基础上得到的磁性铁氧化物纳米材料更是因为在药物靶向运输、肿瘤治疗、磁性流体和化学传感等方面所表现出的广阔应用前景而受到研究人员的青睐。表面增强拉曼散射自从在二十世纪七十年代被发现以来,就由于其在分析物检测方面表现出的高灵敏度和高选择性而备受关注,而强的信号增强能力和较为宽松的检测条件更是使得依此发展起来的SERS技术被广泛地应用于表面科学、生物医学、环境监测和公共安全等多个领域。将相应的磁性纳米材料和贵金属材料(金、银纳米粒子)结合起来,可以使得到的磁性复合物在具有较好磁响应能力的同时表现出较好的SERS增强能力,我们可以利用这种复合物在溶液中对对待测物分子进行有效的富集,随后还可结合外界磁场,使其从混合物溶液中快速分离,并继而进行相应的SERS检测与分析。本文从不同形貌的铁氧体纳米材料的制备入手,获得了具有特殊结构的磁性复合粒子,并进一步实现了其与贵金属材料的有机结合,对其相应的SERS性能进行了探讨,本论文的主要内容如下：(1)利用简单的原料,结合常见的水热反应合成了尺寸分布均匀且形貌良好的纺锤状β-FeOO H,运用各种不同的表征方式对所得β-FeOOH纳米粒子的形貌结构等进行了表征,同时探讨了反应温度和所加入的CTAB量对其形貌的影响。在此基础上我们还尝试着将所得的β-FeOOH纳米粒子置于管式炉中进行煅烧处理,期望能够获得具有良好纺锤形貌的磁性Fe3O4纳米粒子。通过扫描电镜对在不同气氛和温度下煅烧后得到的产物的形貌进行观察,我们发现直接煅烧p-FeOOH纳米粒子难以保持纳米粒子原先的纺锤状形貌,为了解决这一问题,我们尝试在原先的P-FeOOH表面包覆上一层二氧化硅,后再将所得的纺锤状p-FeOOH@SiO2纳米粒子置于氢气气氛下进行高温煅烧,制备得到了具有良好纺锤状形貌且尺寸均匀的Fe3O4@SiO2纳米颗粒,并结合相关手段对其进行了表征。(2)通过简单的水热方法我们得到了具有规整立方状形貌且尺寸分布均匀的α-Fe2O3纳米粒子,后续通过修改后的S tobe r方法使其表面包覆上一层均匀的二氧化硅,并将所得的α-Fe2O3@SiO2纳米颗粒在氢气气氛下高温还原得到了尺寸均匀且分散性良好的立方状Fe3O4@SiO2纳米粒子,后以PVP作为还原剂,采用“一锅煮”的水热方法实现了在Fe3O4@SiO2纳米粒子表面银纳米颗粒的生长。我们利用XRD, TEM, SEM, FTIR等测试手段对所得的各种纳米粒子进行了表征,除此之外,我们还探究了水热反应时间对Fe3O4@SiO2@Ag纳米复合物表面银纳米颗粒生长的影响,同时结合相应的检测设备,对所得复合材料的磁学性质进行了探究,最后将所得到的复合材料作为基底,深入探讨了其相应的SERS性能。实验表明,Fe3O4@SiO2@Ag纳米复合材料能够表现出较好的磁响应性和SERS敏感性,可以在外界磁场的作用下实现对待测分子的分离和富集,在SERS检测应用等方面呈现出十分广阔的前景。更多还原

【Abstract】 In recent years, with the increasing development of nanoscience and nanotechnology, various iron oxide nanomaterials have been fabricated and then applied in science research due to their unique properties. Among them, the magnetic iron oxide nanomaterials attracted considerable researchers’attentions because of their great potential applications in drug delivery, cancer treatment, magnetic fluids and chemical sensor. Since the discovery of surface-enhanced Raman scattering (SERS) in the 1970s, it has aroused intense interest due to its high sensitivity and specificity in analytes detection. The enormous SERS enhancement effect and simple testing condition have enabled SERS technology to be widely used in surface science, biology, medicine pharmacy, environmental monitoring, national security and other fields. The combination of magnetic iron oxide nanomaterials and noble metals can endow the final product dual functions of both magnetic response and local surface plasmon resonance. We can disperse these composites into the analyte solution to achieve the adsorption of analyte molecules. By using an external magnetic field, these composites can be separated from the solution rapidly and then for the further SERS measurement. In this paper, we first tried to fabricate iron oxide nanomaterials with different shapes, then the as-obtained magnetic composites were coated with the noble metal nanomaterials and the SERS properties of the final composites were investigated. The main contents are as following:(1) Uniform and well-dispersed spindle-like β-FeOOH nanoparticles were synthesized with simple reagents through a facile hydrothermal reaction and then characterized by various means. The effects of reaction temperature and CTAB amount on the products morphology were also investigated. Besides, in order to get the desired spindle-like Fe3O4 nanoparticles, the as-prepared β-FeOOH nanoparticles were placed in tube furnace and experienced a calcining process. However, we found that the final calcined products could not maintain the spindle morphology according to their SEM images. In order to address this problem, silica layer was introduced onto the surface of β-FeOOH nanoparticles, after that the monodispersed spindle-like Fe3O4@SiO2 nanoparticles were obtained by calcining β-FeOOH@SiO2 nanoparticles in hydrogen atmosphere and then characterized.(2) Monodispersed cubic α-Fe2O2 nanoparticles were first fabricated by a simple hydrothermal reaction. After that a modified Stober method was applied to coat silica layer onto the surface of α-Fe2O3 nanoparticles. And then the uniform and well-dispersed cube-like Fe3O4@SiO2 core-shell structures were obtained by calcining the as-prepared α-Fe2O3@SiO2 samples in hydrogen atmosphere. By using PVP as reducer, silver nanoparticles were introduced onto the Fe3O4@SiO2 surface through a one-pot hydrothermal reaction. The above obtained samples were characterized by XRD, TEM, SEM and FTIR. Besides, we also investigated the influence of the reaction time on the coverage rate of Ag nanoparticles on the Fe3O4@SiO2@Ag (FSA) surface. Finally, the magnetic and SERS properties of these magnetic composites were studied and discussed. The results showed that the FSA nanocomposites could exhibit good magnetic response and superior SERS sensitivity. The as-prepared FSA nanocomposites could adsorbed analyte molecules in solution and then easily separated with the help of external magnetic field, all of which make the FSA nanocomposites a perfect choice for practical SERS detection applications.更多还原