First-principle study of CO adsorption and oxidation on Sm-doped CeO2(111) surface

Abstract

The surface properties and CO oxidation on Sm-doped CeO₂(111) (denoted as Sm_0.08Ce_0.92O₂(111)) have been studied systematically by using the DFT+U method to reveal the influence of Sm on the catalytic performance of CeO₂(111). The structures and electronic properties of Sm_0.08Ce_0.92O₂(111) are studied. It is found that the oxygen vacancy formation energies are reduced by more than 50 percent after Sm doping compared to the undoped system. In addition, unlike a stoichiometric CeO₂(111) surface observed with only the presence of physisorbed CO, the Sm dopant promotes the direct oxidation of CO by taking away an oxygen atom from the stoichiometric CeO₂(111) surface, thus leading to the formation of a CO₂ molecule and an oxygen vacancy left on the surface. The physical reasons for understanding the above data are analyzed and discussed.