Characterization of silica-gel supported Pt-Cu alloy particles prepared via the sol-gel technique

Silica-gel-supported Pt-Cu alloy particles (diameter 4-8 nm) were prepared via sol-gel processing from mixtures of tetraethoxysilane, 3-(2-aminoethyla mine)propyltriethoxysilane as anchors for metal ions, and acetates of Cu2and [Pt(NH3)(4)](2+) as metal sources. The calcined and reduced materials w ere characterized by transmission electron microscopy (carrier morphology a nd metal dispersion), photoelectron spectroscopy (global charge states) and diffuse reflectance infrared spectroscopy of chemisorbed CO to probe the e lectronic structure of the metal particles. The results obtained by the com bined techniques provide evidence for the formation of supported Pt-Cu allo y particles, the detection of geometric and ligand effects, and an unusual redistribution of intensity between the bands corresponding to CO adsorbed on Cu and Pt atoms.