Roles of oxygen vacancy and O-x(-) in oxidation reactions over CeO2 and Ag/CeO2 nanorod model catalysts

Though the catalytic oxidation of CO, NO and soot over CeO2 could be understood within a similar Mars van Krevelen-type mechanism, these reactions were likely to be driven by different active phases. In this work, several CeO2 and Ag/CeO2 nanorods with different contents of surface oxygen vacancies (Vo-s) and active oxygen species (O-x(-)) were designed as model catalysts. Their catalytic performance indicated that, CO oxidation was determined by pre-existing ceria Vo-s, while Cc participated in NO and soot oxidation directly. Besides, by loading silver onto the high-temperature aged CeO2 nanorods, Ag/CeO2 catalysts with high availability of ceria lattice oxygen were obtained, whose low-temperature oxidation activity was proven comparable to that of the platinum catalysts. In this sense, the model designing in this work not only provided methods to find out proper reactivity descriptors, but also conferred low-cost catalysts with high practical potential. (C) 2018 Elsevier Inc. All rights reserved.