title: A comparative theoretical study of the catalytic activities of Au2(-) and AuAg(-) dimers for CO oxidation.
abstract: The detailed mechanisms of catalytic CO oxidation over Au(2)(-) and AuAg(-) dimers, which represent the simplest models for monometal Au and bimetallic Au-Ag nanoparticles, have been studied by performing density functional theory calculations. It is found that both Au(2)(-) and AuAg(-) dimers catalyze the reaction according to the similar mono-center Eley-Rideal mechanism. The catalytic reaction is of the multi-channel and multi-step characteristic, which can proceed along four possible pathways via two or three elementary steps. In AuAg(-), the Au site is more active than the Ag site, and the calculated energy barrier values for the rate-determining step of the Au-site catalytic reaction are remarkably smaller than those for both the Ag-site catalytic reaction and the Au(2)(-) catalytic reaction. The better catalytic activity of bimetallic AuAg(-) dimer is attributed to the synergistic effect between Au and Ag atom. The present results provide valuable information for understanding the higher catalytic activity of Au-Ag nanoparticles and nanoalloys for low-temperature CO oxidation than either pure metallic catalyst.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University, Jinan, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.forename: Ke
authors.initials: K
authors.lastname: Song
authors.forename: Dongju
authors.initials: D
authors.lastname: Zhang
authors.forename: Chengbu
authors.initials: C
authors.lastname: Liu
mesh_terms: D000497:Alloys / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D019281:Dimerization; D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D011789:Quantum Theory; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D000497:Alloys; D012834:Silver; D006046:Gold; D002248:Carbon Monoxide