title: Direct atomic imaging and density functional theory study of the Au24Pd1 cluster catalyst.
abstract: In this study we report a direct, atomic-resolution imaging of calcined Au24Pd1 clusters supported on multiwall carbon nanotubes by employing aberration-corrected scanning transmission electron microscopy. Using gold atoms as mass standards, we confirm the cluster size to be 25 ± 2, in agreement with the Au24Pd1(SR)18 precursor used in the synthesis. Concurrently, a Density-Functional/Basin-Hopping computational algorithm is employed to locate the low-energy configurations of free Au24Pd1 cluster. Cage structures surrounding a single core atom are found to be favored, with a slight preference for Pd to occupy the core site. The cluster shows a tendency toward elongated arrangements, consistent with experimental data. The degree of electron transfer from the Pd dopant to Au is quantified through a Löwdin charge analysis, suggesting that Pd may act as an electron promoter to the surrounding Au atoms when they are involved in catalytic reactions.
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. z.li@bham.ac.uk.
authors.forename: A
authors.initials: A
authors.lastname: Bruma
authors.forename: F R
authors.initials: FR
authors.lastname: Negreiros
authors.forename: S
authors.initials: S
authors.lastname: Xie
authors.forename: T
authors.initials: T
authors.lastname: Tsukuda
authors.forename: R L
authors.initials: RL
authors.lastname: Johnston
authors.forename: A
authors.initials: A
authors.lastname: Fortunelli
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li