Interface interactions and CO oxidation activity of Ag/CeO2 catalysts: A new approach using model catalytic systems

Abstract In this paper, we studied in details the nature of the Ag-CeO 2 interaction and its influence on the catalytic activity in CO oxidation at low temperature. Ag/CeO 2 catalysts were prepared by pulsed laser ablation in liquids (PLA). This method provided the preparation of highly dispersed particles of both an active component and a support. The initial Ag/CeO 2 composites did not show activity in the CO oxidation at temperatures 2 to ionic Ag + species. The ionic species were stabilized on the surface of CeO 2 without incorporation into the ceria volume. The catalyst activated at 450 °C demonstrated high stability under catalytic conditions due to the effective reversible transition Ag + -CeO 2  ↔ Ag n °/CeO 2 , where Ag n ° – small metal clusters on the CeO 2 surface. It is proposed that such reversible transition is facilitated by the defects on the surface of CeO 2 nanoparticles. With an increase of the calcination temperature of Ag/CeO 2 catalysts above 600 °C, the efficiency of the redox transition decreased due to annealing of CeO 2 defects and formation of better-crystallized particles. As a result, catalysts calcined at T>600 °C did not show low-temperature catalytic activity.