title: Catalytic activity of Pd ensembles over Au(111) surface for CO oxidation: a first-principles study.
abstract: Employing the first-principles pseudopotential plane-wave methods and nudged-elastic-band simulations, we studied the reaction of CO oxidation on Pd-decorated Au(111) surface. We found that the contiguous Pd ensembles are required for the CO + O(2) reaction. Interestingly, Pd dimer is an active site for the two-step reaction of CO+O(2)→OOCO→CO(2)+O, and a low energy barrier (0.29 eV) is found for the formation of the intermediate metastable state (OOCO) compared to the barrier of 0.69 eV on Pd trimer. Furthermore, the residual atomic O in the CO + O(2) reaction can be removed by another CO on Pd dimer with the barrier of 0.56 eV close to the value of 0.52 eV on Pd monomer via Langmuir-Hinshelwood mechanism. The higher energy barriers (0.96 and 0.64 eV) are also found for the CO + O reaction on Pd trimers. The calculated results indicate Pd dimer is highly reactive for CO oxidation by O(2) via association mechanism on Pd-decorated Au(111) surface.
authors.affiliation: College of Materials Science and Engineering, Hunan University, ChangSha 410082, China. dwyuan@hnu.edu.cn
authors.forename: D W
authors.initials: DW
authors.lastname: Yuan
authors.forename: Z R
authors.initials: ZR
authors.lastname: Liu
authors.forename: J H
authors.initials: JH
authors.lastname: Chen