Ag@SiO_2纳米颗粒的制备和光谱性能研究

Study on Preparation of Ag@SiO_2 Nanoparticles and Its Optical Properties

利用还原法制备纳米银溶胶,采用改进的Stber法分别于乙醇和正丁醇溶剂中制备Ag@SiO2。透射电镜(TEM)表明在乙醇溶剂中实现了包覆,X射线衍射(XRD)表明纳米银具有规则的面心立方结构,X射线光电子能谱(XPS)则进一步表明银颗粒表面构筑了SiO2壳层。壳层厚度对银溶胶的光谱性质有显著影响,紫外可见吸收光谱表明最大吸收峰发生红移;荧光光谱表明SiO2壳层的包覆使纳米银的激发和发射光谱强度降低。

Silver nanoparticles are prepared by reducing method. Ag@SiO2 composite nanoparticles with a coreshell structure are prepared by a modified St6ber method in ethanol and t-butanol solvents, respectively. TEM images show that regular SiO2-eovered silver nanopartieles （briefly-marked as Ag@SiO2 ） can be obtained in ethanol, but not in t-butanol. The XRD measurement indicates that the silver nanoparticles are face-centered cubic （fcc） structure with high crystallinity. XPS measurement shows that the complex bonding is established between Ag core and SiO2 shell. The shell thickness of silver nanoparticles play a notable role in spectral properties. UV-visible spectroscopy records that the plasmon resonance peak of silver nanoparticles is red-shifted after the coverage of SiO2. As capping effect, the fluorescence intensity related to SPR of Ag core is reduced by SiO2 shell.