Physicochemical characterization of Au/CeO2 solid. Part 1: the deposition–precipitation preparation method

Abstract

Au/CeO2 (4 wt.% gold) solid was prepared using the deposition–precipitation method. The deposition of gold on ceria did not affect its specific surface area (122 m2 g−1/400 °C). The average diameter of gold particles obtained was estimated to be equal to 3.9 nm. Moreover, 60% of the gold was in the form of nanoparticles with a size ranging between 3 and 4 nm. 80% of the gold in the nanoparticles was in the metallic form Au0 and 20% was present as Au+. These latter cations interact directly with the O2− anions of CeO2. When evacuated at 400 °C for 1 h, the cations were reduced into Au0. All the adsorptions were performed on solids treated under vacuum at 400 °C for 1 h. The adsorption of O2 at room temperature led to the formation of O2− species. The adsorption of 17O-enriched molecular oxygen demonstrated that the two oxygen atoms in O2− are equivalent. When CO was introduced, it reacted with the O2− of the support to give CO2−. When NO2, NO or N2O were added at room temperature, they decomposed to form adsorbed O2− species at the surface of the solid. Highlights ► Au/CeO2 solid prepared by the deposition–precipitation method presents highly dispersed Au nanoparticles. ► The adsorption on Au/CeO2 of NO, NO2, N2O and O2 leads to the formation of O2−. ► The adsorption of CO on Au/CeO2 leads to the formation of CO2−. ► The adsorption of 17O2 on Au/CeO2 shows that the two adsorbed oxygen are equivalent.