Direct atomic imaging and density functional theory study of the Au 24Pd1 cluster catalyst

TitleDirect atomic imaging and density functional theory study of the Au 24Pd1 cluster catalyst
Publication TypeJournal Article
Year of Publication2013
AuthorsBruma, A, Negreiros, FR, Xie, S, Tsukuda, T, Johnston, RL, Fortunelli, A, Li, ZY
ISSN20403364 (ISSN)
KeywordsAberration-corrected scanning transmission electro, Atomic-resolution imaging, Atoms, Catalysis, Catalytic reactions, Charge analysis, Computational algorithm, Density functional theory studies, Density functionals, Electron transfer, Image reconstruction, Palladium, Transmission electron microscopy

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. © The Royal Society of Chemistry 2013.