Microwave synthesis of Ag@SiO2 core–shell using oleylamine

Ag nanoparticles were synthesized using microwave irradiation. Oleylamine was used as a stabilizer and capping agent, dimethylformamide as a reducing agent, and deionized water as a solvent. Synthetic parameters of Ag nanoparticles were optimized systematically. The Ag nanoparticles were used subsequently without any treatment in the preparation of Ag@SiO2 core–shell nanoparticles. UV–Vis spectroscopy shows a characteristic plasmon peak at 407 and 430 nm for Ag nanoparticles and Ag@SiO2 core–shells, respectively. Transmission electron microscope images show that Ag nanoparticles have the average size of 15 nm. It is also depicted that the core–shell structure was formed uniformly with the average size of 100 and 25 nm for Ag core and SiO2 shell, respectively. The application of Na-Cit in the preparation of core–shells yields single Ag core structure.