X-ray photoelectron spectroscopy of Au/Fe2O3 catalysts

Gold catalysts supported on iron oxide have been characterized by X-ray pho toelectron spectroscopy (XPS). Depending on the method of preparation and p retreatment, different gold species have been detected on the catalyst surf ace. In the absence of thermal treatment, the XPS spectra of the impregnate d samples show the formation of gold(III) (oxy)chloride species. No metalli c gold is formed. Both metallic and oxidized gold species are instead prese nt on the surface of the samples prepared by coprecipitation. Oxidized gold (III) species are predominant on the uncalcinated catalysts. After treatmen t at high temperature and/or under reaction conditions the amount of metall ic gold increases. The XPS data have been correlated with the activity of t he investigated catalysts in the oxidation of carbon monoxide at low temper ature.