Physicochemical characterization of Au/CeO2 solid. Part 1: The deposition-precipitation preparation method

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 m(2) g(-1)/400 degrees 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 Au-0 and 20% was present as Au+. These latter cations interact directly with the O2- anions of CeO2. When evacuated at 400 degrees C for 1 h, the cations were reduced into Au-0. All the adsorptions were performed on solids treated under vacuum at 400 degrees C for 1 h. The adsorption of O-2 at room temperature led to the formation of O-2(-) species. The adsorption of O-17-enriched molecular oxygen demonstrated that the two oxygen atoms in O-2(-) are equivalent. When CO was introduced, it reacted with the O-2(-) of the support to give CO2-. When NO2, NO or N2O were added at room temperature, they decomposed to form adsorbed O-2(-) species at the surface of the solid. (C) 2012 Elsevier B.V. All rights reserved.