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

摘要

The surface properties and CO oxidation on Sm-doped CeO2(111) (denoted as Sm0.08Ce0.92O2(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 Sm0.08Ce0.92O2(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.