Self assembly of the metal nanoparticles: Formation of the highly oriented, core-shell type, bimetallic gold-silver film

A synthetic route is presented for the preparation of a bimetallic gold-silver film under UV-irradiation. Methoxy polyethylene glycol, a water soluble polymer, is used as the reducing agent for the gold and silver ions in the presence of a ultra-violet source that results in the formation of gold and silver bimetallic nanoparticles. During stirring a centrifugal force is generated at the center of the solution, which results in a coalescence of the nanoparticles and forms a self-assembly of small subunits that ultimately produces a film-like network. UV-vis spectra and scanning electron microscopy were used to determine, respectively, the configuration of the gold and the silver in the nanoparticles, a Au_core-Ag_shell structure, and the thickness of the film.