Role of Dopant in the Formation of Reactive Oxygen Species and Oxidation Catalysis on Ceo2(111)

We theoretically investigate the role of nine 3d-5d Groups 9-11 metals substitutionally doped into CeO2(111) in i) oxygen vacancy (VO) formation; ii) H and CO adsorption; iii) H2, C3H8, and CO oxidation. All dopants significantly lower the VO formation energy vs. un-doped CeO2(111), which becomes negative for Ni, Pd, Pt, Cu, and Ag. Surface lattice O and O2/VO species at the doped sites are significantly more active toward H than on un-doped CeO2(111). CO chemisorption on the doped sites is also strongly enhanced. Yet, the reaction energy of H and CO removal via VO formation is independent of doping because they are iso-reduction steps. Whether substitutional doping promotes an oxidation reaction depends on to whether the adsorption step (e.g., dissociative via H-H or C-H cleavage, or molecular as CO) or the desorption step via vacancy formation is the bottleneck. When the latter is, doping would have little promotional effect.