Fabrication of Cu@Ag core–shell nanoparticles for nonlinear optical applications

We report the preparation of the core–shell structured Cu@Ag nanoparticles by a simple wet chemical route at room temperature. The surface plasmon resonance band at 405 nm is indicative of the formation of Cu@Ag nanoparticles. The powder X-ray diffraction and energy dispersive X-ray analyses were carried out to elucidate the structure and chemical composition respectively. The morphological investigations made by electron microscopes revealed that the particles are spherical in shape with core–shell structures having size of about 50 nm. The X-ray photoelectron spectroscopy was performed to elucidate surface state composition of the core–shell structured nanoparticles based on the binding energies and confirmed the formation of Cu@Ag core–shell nanoparticles. The enhanced non-linear optical response of the Cu@Ag core–shell nanoparticles was demonstrated by z-scan experiment using He–Ne laser. This report provides a simple, economical and practical technology to fabricate Cu@Ag core–shell nanoparticles with enhanced nonlinear optical properties.