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Abstract
In this article, Ag-SiO2 composite nanoparticles with a core-shell structure were prepared by a very simple and rapid wet chemical method in different solvents such as methanol, ethanol and isopropanol, respectively, transmittance electron microscopy (TEM) images show that regular SiO2-covered silver nanoparticles (briefly-marked as Ag@SiO2) can be obtained in ethanol and isopropanol, but not in methanol. The x-ray diffraction (XRD) measurement indicates that the silver nanoparticles are face-centered cubic (fcc) structure with high crystallinity. X-ray photoelectron spectroscopy (XPS) measurement shows that the binding energy of O1 s in Si-O-Ag is lower than that in Si-O-Si, which means that the complex bonding is established between Ag core and SiO2 shell. Ultraviolet-visible (UV-vis) spectroscopy records that the plasmon resonance peak of silver nanoparticles is shifted after the coverage of SiO2. As capping effect, the fluorescence intensity related to surface plasmon resonance (SPR) of Ag core is reduced by SiO2 shell.
Acknowledgements
This research was financially supported by National Program on Key Basic Research pre-Projects (pre973) through contract grant number 2004CCA04800, and the Natural Foundation of Shandong Province (2009–2011).
