Highly Dispersed Metal Colloids: Spectroscopy and Surface Chemistry in Solution

Abstract The adsorption of carbon monoxide on colloidal solutions of nanosize particles of palladium and palladium-copper alloys is reported. Partial coverage spectra of adsorbed CO on a palladium colloid show similarity with those for CO on single crystal and supported palladium with the development of first triply bridged CO, then doubly bridged CO which dominates the spectrum to higher coverages, and linear CO which appears at the highest coverages. Addition of a second metal, copper, to the palladium surface perturbs the spectrum of adsorbed CO in a manner consistent with a simple dilution effect. Liquid phase 13 C NMR shows that the adsorption-desorption exchange reaction of CO in the presence of the palladium-copper alloy is faster than for the pure palladium.