Synergistic activity of gold-platinum alloy nanoparticle catalysts

The understanding of the composition-activity relationship is essential for the exploitation of the synergistic properties of multimetallic nanoparticles in catalytic reactions. This paper focuses on the discussion of findings from the investigation of bimetallic gold-platinum (AuPt) nanoparticles of different compositions. Infrared spectroscopic data for CO adsorption on silica-supported AuPt nanoparticles reveal that the surface binding sites are dependent on the bimetallic composition. The analysis of this dependence further led to the conclusion that the relative Au-atop and Pt-atop sites for the linear CO adsorption on the nanoparticle surface are not only correlated with the bimetallic composition, but also with the electronic effect as a result of the d-band shift of Pt in the bimetallic nanocrystals, which is the first demonstration of the nanoscale core-surface property correlation for the bimetallic nanoparticles over a wide range of bimetallic composition. A further examination of the electrocatalysis data for methanol oxidation reaction on carbon-supported AuPt nanoparticle catalysts reveal important insights into the participation of CO or OH adsorption on Au sites and the catalytic activity of Pt in the AuPt alloys with relatively high Au concentration. Implications of these findings to synergistic correlation of the bifunctional activity of the bimetallic nanoparticle catalysts with the bimetallic composition are also discussed. (C) 2007 Elsevier B.V. All rights reserved.