Synthesis of Au-core/Pt-shell nanoparticles within thermally evaporated fatty amine films and their low-temperature alloying

The low-temperature alloying of bimetallic Au-Pt nanoparticles entrapped wi thin thermally evaporated fatty amine films by a novel ion-exchange techniq ue is described. Nanoparticles of gold and platinum were grown in thermally evaporated octadecylamine films by immersion of the film sequentially in s olutions containing AuCl4- ions and PtCl62- ions followed by their in situ reduction at each stage. Entrapment of AuCl4- and PtCl62- ions in the octad ecylamine (ODA) film occurs by selective electrostatic binding with the amm onium ions in the fatty amine matrix. This process leads to the formation o f a Au-core/Pt-shell structure of the nanoparticles within the lipid matrix . Thermal treatment of the ODA-(Au-core/Pt-shell) nanocomposite film at 150 degreesC resulted in the formation of a Au-Pt alloy. The process of AuCl4- and PtCl62- ion incorporation in the ODA matrix and synthesis of the Au-Pt alloy were followed by quartz crystal microgravimetry, Fourier transform i nfrared spectroscopy, UV-vis spectroscopy, and X-ray diffraction measuremen ts.