title: Regioselective Atomic Rearrangement of Ag-Pt Octahedral Catalysts by Chemical Vapor-Assisted Treatment.
abstract: Thermal annealing is a common, and often much-needed, process to optimize the surface structure and composition of bimetallic nanoparticles for high catalytic performance. Such thermal treatment is often carried out either in air or under an inert atmosphere by a trial-and-error approach. Herewith, we present a new chemical vapor-assisted treatment, which can preserve the octahedral morphology of Ag-Pt nanoparticles while modifying the surface into preferred composition arrangements with site-selectivity for high catalytic activity. In situ environmental transmission electron microscope (ETEM) study reveals a relatively homogeneous distribution of Ag and Pt is generated on the surface of Ag-Pt nanoparticles upon exposure to carbon monoxide (CO), whereas Pt atoms preferably segregate to the edge regions when the gas atmosphere is switched to argon. Density functional theory (DFT) calculations suggest stabilization of Pt atoms is energetically favored in the form of mixed surface alloys when CO vapor is present. Without CO, Ag and Pt phase separate under the similar mild treatment condition. There exists a close correlation between the tunable surface structures and the catalytic activities of Ag-Pt octahedral nanoparticles.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 114 Roger Adam Laboratory, MC-712, 600 South Methews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Yung-Tin
authors.initials: YT
authors.lastname: Pan
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 114 Roger Adam Laboratory, MC-712, 600 South Methews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Linqing
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , 1006 Materials Research Laboratory, 104 South Goodwin Avenue, Urbana, Illinois 61801, United States.
authors.forename: Yu-Tsun
authors.initials: YT
authors.lastname: Shao
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , 1006 Materials Research Laboratory, 104 South Goodwin Avenue, Urbana, Illinois 61801, United States.
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Zuo
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 114 Roger Adam Laboratory, MC-712, 600 South Methews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
keywords: Ag−Pt; Bimetallic nanoparticle; ETEM; chemical vapor assisted processing; hydrogenation; regioselective