A DFT plus U study of the structures and reactivities of polar CeO2(100) surfaces

Density functional theory calculations corrected by on-site Coulomb interactions were carried out to study the structures of polar CeO2(100) surfaces as well as activities during catalytic CO oxidation. The stabilities of various CeO2(100) termination structures are discussed, and calculated energetics are presented. The most stable CeO2(100) surface was obtained by removing half the outermost full layer of oxygen and the surface stability was found to decrease as the exposed oxygen concentration was increased. Assessing the reaction pathways leading to different final products during CO oxidation over the most stable CeO2(100) surface, we determined that the formation of carbonate species competed with CO2 desorption. However, during CO oxidation on the less stable CeO2(100) surfaces having more exposed oxygen, the CO is evidently able to react with surface oxygen, leading to CO2 formation and desorption. The calculation results and electronic analyses reported herein also indicate that the characteristic Ce 4f orbitals are directly involved in determining the surface stabilities and reactivities. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.