Synthesis and structural characterization of Co immersed in Ag nanoparticles obtained by successive reactions in microemulsions

Co@Ag nanoparticles have been prepared in microemulsions by the successive reaction technique. It was observed that, under the experimental conditions of this study, the size of the Co nuclei is limited by the reactant concentration (approx. 0.7 nm), whereas the Ag covering is templated by the microemulsion droplet size (approx. 7 nm). The as-prepared particles mainly contain clusters in the form of Co3O4, which evolves to Co as the samples are annealed in a reducing atmosphere at high temperatures. At temperatures >300 °C the pasivating surfactant layer decomposes with the subsequent growth of the nanoparticles, converging their properties to Co and Ag bulk.