共振峰精确可调的银纳米颗粒光化学合成方法研究

发布时间：2019-04-02 17:23

【摘要】：贵金属(尤其是Au和Ag)纳米材料因其在光学、电学、磁学以及催化等方面表现出的独特性质引起了科学界广泛的关注。尤其在光学方面,金属纳米颗粒的局域表面等离子体共振(Local surface plasmonic resonance,LSPR)特性已经在光学成像、生物传感、表面增强光谱等领域被广泛应用。LSPR的关键性能参数之一是共振吸收峰的位置,它随金属纳米颗粒的形貌和尺寸而变化。以银纳米颗粒(Ag nanoparticles,Ag NPs)为例,尽管通过已有的实验方法,人们已经获得了不同形状和尺寸的Ag NPs,但尚无法精确调节它的共振峰位置。针对上述问题,本论文通过改进传统的Ag NPs光化学合成工艺,建议了一种共振吸收峰精确可调的Ag NPs合成方案。该方案分两个步骤:首先用紫外光照射前驱溶液(以柠檬酸钠、硝酸银、光引发剂I-2959和去离子水按一定比例配制所得),获得Ag NPs种子溶液;其次再用具有特定波长的LED作为诱导光源,通过光化学反应来制备不同形状的Ag NPs。我们的创新点是在光化学反应中引入温控环节,在特定温度下,通过控制光照时间来对共振峰的位置精确调节。毕业论文的主要内容概括如下:首先,基于传统光化学合成工艺,我们获得了球形、十面体、六边形、三角形等形状各异的Ag NPs,并借助透射电子显微镜(Transmission Electron Microscope,简称TEM)、紫外可见吸收光谱(Ultraviolet-visible spectroscopy,简称UV-Vis)等测试手段对合成的Ag NPs的尺度、形貌以及生长机理等进行了研究。实验表明我们获得的Ag NPs形貌好于文献报导。其次,以十面体Ag NPs为例,论文实验验证了在特定温度下,通过控制光化学合成的光照时间,实现Ag NPs共振峰精确可调的技术思路。实验中,我们在不同反应温度(例如30°C、40°C、50°C、60°C和70°C)下合成十面体Ag NPs,发现在特定的控温下,合成纳米颗粒的共振峰位置λmax随反应时间t增加,线性红移。因此,能通过控制t来实现λmax的精确调节。此外,我们也证实了反应温度的升高,会加快Ag NPs的成核和生长过程,所以较高温度下生成Ag NPs的速率较快。最后,本论文也采用有限元法,对实验中出现的共振峰精确可调现象的物理起源做了数值模拟分析。结果证实纳米颗粒的粒径和倒角r等因素造成了前述的共振峰红移现象。相关理论工作有助于更好地理解光化学合成Ag NPs的微观过程。
[Abstract]:Precious metal (especially Au and Ag) nanomaterials have attracted much attention of the scientific community because of their unique properties in optical, electrical, magnetic and catalytic fields. In particular, in the optical field, the local surface plasmon resonance (Local surface plasmonic resonance,LSPR) characteristics of metal nanoparticles have been applied in optical imaging, biosensors, Surface enhanced spectroscopy is widely used. One of the key parameters of LSPR is the position of resonance absorption peak, which varies with the morphology and size of metal nanoparticles. Taking silver nanoparticles (Ag nanoparticles,Ag NPs) as an example, although different shapes and sizes of Ag NPs, have been obtained through the existing experimental methods, it has not been possible to accurately adjust the position of its resonance peaks. In order to solve the above problems, by improving the traditional photochemical synthesis process of Ag NPs, a precise and adjustable Ag NPs synthesis scheme with resonant absorption peak is proposed in this paper. The scheme is divided into two steps: firstly, Ag NPs seed solution is obtained by ultraviolet irradiation of precursor solution (prepared with sodium citrate, silver nitrate, photoinitiator I, 2959 and deionized water in a certain proportion). Secondly, LED with specific wavelength was used as the induced light source, and Ag NPs. with different shapes was prepared by photochemical reaction. Our innovation is to introduce temperature control into photochemical reaction, and to adjust the position of resonance peak precisely by controlling illumination time at certain temperature. The main contents of the thesis are summarized as follows: firstly, based on the traditional photochemical synthesis process, we obtained spherical, decahedral, hexagonal and triangular Ag NPs, with different shapes and referred to as TEM), by means of transmission electron microscope (Transmission Electron Microscope,). The size, morphology and growth mechanism of the synthesized Ag NPs were studied by UV-vis absorption spectroscopy (Ultraviolet-visible spectroscopy, UV-Vis) and so on. The experimental results show that the morphology of Ag NPs obtained by us is better than that reported in the literature. Secondly, taking decahedron Ag NPs as an example, the technical idea of precisely adjusting the resonance peak of Ag NPs at a specific temperature is verified by controlling the light time of photochemical synthesis. In the experiments, we synthesized decahedral Ag NPs, at different reaction temperatures (for example, 30 掳C, 40 掳C, 50 掳C, 60 掳C and 70 掳C) and found that the position 位 max of the synthesized nanoparticles shifted linearly red with the increase of reaction time t at a specific temperature control. Therefore, the precise adjustment of 位 max can be realized by controlling t. In addition, we also confirmed that the increase of reaction temperature will accelerate the nucleation and growth process of Ag NPs, so the rate of Ag NPs formation is faster at higher temperature. Finally, finite element method (FEM) is used to simulate the physical origin of the exact tunable phenomenon of resonance peaks in the experiment. The results show that the red shift of the resonance peak is caused by the particle size and chamfer r. The related theoretical work is helpful to better understand the microcosmic process of photochemical synthesis of Ag NPs.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.122

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