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

Abstract

Silica-gel-supported Pt–Cu alloy particles (diameter 4–8 nm) were prepared ia sol–gel processing from mixtures of tetraethoxysilane, 3-(2-aminoethylamine)propyltriethoxysilane as anchors for metal ions, and acetates of Cu²⁺ and [Pt(NH₃)₄]²⁺ as metal sources. The calcined and reduced materials were characterized by transmission electron microscopy (carrier morphology and metal dispersion), photoelectron spectroscopy (global charge states) and diffuse reflectance infrared spectroscopy of chemisorbed CO to probe the electronic structure of the metal particles. The results obtained by the combined techniques provide evidence for the formation of supported Pt–Cu alloy 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.