Reaction of NO on CeO2 and Rh/CeO2 thin films supported on alpha-Al2O3(0001) and YSZ(100)

The adsorption and reaction of NO on ceria-based model catalysts was studie d using a combination of temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). Specific systems investigated included: C eO2(111), CeO2/alpha -Al2O3(0001), CeO2/YSZ(100), Rh/alpha -Al2O3(0001), Rh /CeO2/alpha -Al2O3(0001), and Rh/CeO2/YSZ(100). The results of this study s how that NO does not adsorb on fully oxidized CeO2 surfaces, while on parti ally reduced CeO2 surfaces NO adsorbs and dissociates. The reaction of NO o n Rh supported on a ceria thin film was found to be similar to that for rea ction on Rh/alpha -Al2O3(0001) and Rh single crystals as long as the surfac e of the ceria film was fully oxidized. For Rh supported on partially reduc ed CeO2, adsorbed oxygen atoms, formed via dissociation of NO, migrated fro m the Rh to the ceria resulting in oxidation of the surface of the oxide fi lm. The results of this study also demonstrate that interactions at the CeO 2-YSZ(100) interface influence the extent of reduction of the ceria film, i ts thermal stability, and oxygen ion transport properties. (C) 2001 Elsevie r Science B.V. All rights reserved.