Synthesis and characterization of Co@Ag core–shell nanoparticles

A micellar method has been used to prepare silver-coated cobalt (Co@Ag) nanoparticles. The synthesized particles have been deeply characterized by several methods, i.e., XRD, UV–Vis, TEM, XPS, and electrochemical techniques. There is every indication that the obtained particles show a truly core–shell structure. All the nanoparticles obtained under different conditions are in the size range 3–5 nm. High-resolution TEM (HRTEM), Fast Fourier Transformation (FFT), and Selected Area Electron Diffraction (SAED) indicated that the presence of hcp-Co and fcc-Ag, in which cobalt is located in the central area; meanwhile silver is at the edges of the nanoparticle. The absorption band of the Co@Ag colloid shifts to a longer wavelength and broadens relative to that of pure silver colloid. Voltammetric characterization allowed to determine the coverage of the cobalt core.