Titania-supported PdAu bimetallic catalysts prepared from dendrimerencapsulated nanoparticle precursors

In this communication, we report the synthesis and characteriza-tion of TiO2-supported PdAu bimetallic nanoparticle catalysts prepared using dendrimer-encapsulated nanoparticles (DENs).1 The key result is that the compositional fidelity of the original bimetallic DENs, and to some extent their size, is retained in the supported catalyst after removal of the dendrimer template by calcination at 500 °C. Additionally, the gas-phase catalytic activity for CO oxidation is higher for the bimetallic catalysts than that for the corresponding Pd-only and Au-only monometallics.2,3 It has previously been shown that 1-3-nm diameter alloy and core-shell bimetallic PdPt,4,5 PdAu,6 PdRh,7 and AuAg8 nanopar-ticles can be synthesized within dendrimer templates.1 The resulting materials are characterized by a high degree of uniformity in size, structure, and elemental composition, and in some cases they have enhanced solution-phase catalytic activities compared to the ana-logous monometallic materials.4-7 There are also a few examples of dendrimer/nanoparticle composites of various sorts being use