Microwave synthesis of bimetallic nanoalloys and CO oxidation on ceria-supported nanoalloys

Abstract

A facile and fast microwave irradiation (MWI) method has been developed to prepare a wide variety of pure metallic and bimetallic alloy nanoparticles with controlled size and shape. The important advantage of microwave dielectric heating over convective heating is that the reactants can be added at room temperature (or slightly higher temperatures) without the need for high-temperature injection. The method allows the passivation of the nanocrystals by using a mixture of olyel amine and oleic acid as a solvent, a reducing agent, and a capping material. We investigate the controlled synthesis of nanoalloys among the nanocrystals of Au, Ag, Pt, Pd, Ru, Rh, Cu, and Ni by studying the changes in the structural and optical properties of the resulting nanoalloys with respect to the individual metals. Using the same method, we also report the synthesis of selected nanoalloys supported on ceria nanoparticles as nanocatalysts for CO oxidation. The catalytic activities for CO oxidation are presented and discussed. High activity and thermal stability have been observed for the nanoalloys according to the order CuPd > CuRh > AuPd > AuRh > PtRh > PdRh > AuPt. The method could be applied for the synthesis of multimetallic nanoalloys with novel properties resulting from the different metallic properties coupled together in a single nanoalloy. © 2009 American Chemical Society.