Juan Carlos Flores defends his thesis on the synthesis of new functionalized nano-particles.

This work presents the results of obtaining different core-shell type structures of silver nanoparticles functionalized with silica. By means of the modified Stöber method, the structures obtained are silica@Ag and Ag@silica. To corroborate the formation of core-shell structures, UV-Vis, SEM, TEM, XRD studies, among others, were carried out, which determined the composition, morphology and crystal structure of submicron and even nanometric size particles. Through the analysis of the results obtained, the reaction mechanisms for the formation of the core-shell structures are proposed. On the other hand, a study of very slowly evaporated and dried samples of functionalized silver nanoparticle core-shell structures on the surface of silica spheres is presented. The characterization studies by EDS, XRD, HRTEM and HAADF STEM reveal the coexistence of silver nanoparticles and silver oxide nanoparticles anchored to the surface of submicron silica spheres. Ag2O nanoparticles resulted from the transformation of Ag to Ag2O within the dehydrated sample at room temperature, preserved in a dark place and exposed to air. The predominant sizes of Ag nanoparticles are around 2-3 nm, and Ag2O nanoparticle sizes are above 10 nm.