Abstract
Bimetallic Pd-Ag nanoparticles (NPs) were obtained by polyol method in the presence of poly (vinylpyrrolidone), PVP, as capping agent. The reduction of silver and palladium precursors was performed in argon inert atmosphere by successive reduction, or coreduction approach. In the successive reduction, AgNO3 solution was injected in the ethylene glycol solution of PVP at 140°C, followed by the injection of [Pd(NH3)4]Cl2 solution. The obtained bimetallic Pd-Ag NPs exhibited cluster structure, with the surface reach in silver. The NPs size was in the range of 30 – 58.5 nm with the average dimention of 41.5 nm. The coreduction approach consists in the hot injection of both metal precursors as complex ammine dissolved in ethylene glycol. By this method, smaller Pd-Ag NPs with the average sizes in the range 16 – 30 nm were obtained, depending on the synthesis parameters. The influence of metal cations : PVP molar ratio, metal cations concentration, Ag : Pd atomic ratio and the reduction temperature on the composition and morphology of the bimetallic NPs was studied. For both reduction approaches, based on the experimental data, two different reduction patways were proposed. Keywords: bimetallic nanoparticles, Ag, Pd, PVP, polyol method, coreduction, successive reduction