Synthesis of Mono- and Bimetallic Au-based Nanoparticle Catalysts Utilizing Solid Phase Dendrimer Templates

Introduction The desire to controllably tune catalyst properties has generated increased interest in the controlled preparation of supported nanoparticle catalysts. Particle size, composition, and morphology may have substantial influences on catalytic activity and, more importantly, selectivity. However, few preparative routes exist to prepare supported catalysts of welldefined morphologies. Starburst polyamidoamine (PAMAM) dendrimers are a specific class of nearly monodisperse, hyperbranched polymers that can be employed in nanoparticle syntheses. PAMAM dendrimers can be used to both template and stabilize a wide variety of monoand bimetallic metal nanoparticles (NPs). In this synthetic scheme, metal precursors are first bound to the interior amine groups of the PAMAM dendrimer; addition of a reducing agent prepares particles that are essentially trapped within the dendrimer interior. The dendrimer mediated synthesis allows for greatly increased control over particle size and composition. For bimetallic particles, well-mixed and core-shell particles on the order of 2 nm in diameter can be selectively prepared. It is also possible to anchor the dendrimer to a resin bead or other solid support to synthesize Au-based MPC catalysts.