Structure sensitivity of ceria-supported Au catalysts for CO oxidation

Abstract

Single-atom catalysis is at the center of the attention of the heterogeneous catalysis community. It remains a challenge to determine the thermodynamic stability of single atoms on an oxide support and compare their activity to that of small clusters and nanoparticles. We conducted density functional theory calculations to compare the stability of Au(CO) complexes on the CeO2(111) terrace and step-edge of CeO2(111) against CeO2(111)-supported nanoparticles. The different single atom Au and Au cluster models were compared for CO oxidation at low temperature. Trapped as dopants substituting for Ce in the surface or in a ceria O vacancy, Au cannot catalyze CO oxidation. Single Au atoms at step-edges represent candidate active sites for low-temperature CO oxidation. The CO oxidation at the interface between Au nanoparticles and CeO2 can directly take place through a Mars-van Krevelen mechanism and account for a promising reactivity when the dislodgment of Au(CO) complex is hindered. The possibility of CO-induced dislodgement of a single Au atom depends critically on the topology of the Au-CeO2 interface.