Authors: M. Blosi, S. Albonetti, F. Gatti, M. Dondi, A. Migliori, L. Ortolani, V. Morandi, G. Baldi
Affilation: Istec-CNR, Italy
Pages: 352 - 355
Keywords: Au, Ag, colloidal nanoparticles, green synthesis, microwave, core-shell
The research was focused on the synthesis of Au, Ag and Au-Ag core-shell sols, prepared by a patented microwave-assisted green synthesis. The method provides colloidal mono and bimetallic nanoparticles throughout the reduction of precursor’s salts by glucose in alkaline water. This water synthesis showed several advantages with respect to other methods, in fact it is environment friendly and carried out at low temperature. Moreover, the colloids exhibited fundamental properties for an industrial scale up: very high metal concentration (higher than literature) and long time stability (12 months). Particle size-control and colloidal stability were achieved thanks to the reaction optimization, combined with microwave heating that provides some advantages over the conventional methods. HRTEM showed that nanoparticles are spherical with a diameter ranging from 8 to 15 nm, depending on Ag content, with narrow particle size distribution. The formation of core-shell nanostructures was confirmed by the red-shift of the plasmon resonance band increasing the Au content and by the EDX-STEM line scanning across the nanoparticles. The samples were tested as catalysts, as antibacterial for surface treatments and as ceramic inks for ink-jet printing technology. Catalytic activity of the prepared nanocrystals was evaluated in the reduction of p-nitrophenol in the presence of NaBH4.