Synthesis and Characterization of Dendrimer Templated\nSupported Bimetallic Pt−Au Nanoparticles

Abstract

Bimetallic dendrimer-stabilized nanoparticles (DSNs) were used to prepare supported Pt−Au\ncatalysts within the bulk miscibility gap for this binary system. Hydroxy-terminated generation 5 PAMAM\ndendrimers were used to prepare Cu⁰ nanoparticles (NPs). The Cu⁰ NPs were subsequently used to reduce\nK₂PtCl₄ and HAuCl₄, preparing stabilized bimetallic Pt−Au NPs with a 1:1 stoichiometry. The stabilized\nNPs were adsorbed onto a high surface area silica support and thermally activated to remove the dendrimers.\nTransmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and infrared spectroscopy\nof adsorbed CO showed that this preparation route resulted in NPs in which the two metals are intimately\nmixed and that the majority of the bimetallic NPs were smaller than 3 nm. Further, the bimetallic NPs were\nhighly active for CO oxidation catalysis near room temperature and showed evidence of CO induced\nrestructuring at ambient temperatures.