Carbon monoxide-induced adatom sintering in a Pd–Fe3O4 model catalyst

Although the coarsening of catalytically active metal clusters can be accelerated by the presence of gases, the role played by gas molecules is difficult to ascertain. Carbon monoxide-induced coalescence of Pd adatoms supported on a Fe 3 O 4 surface is now investigated at room temperature, and Pd-ca...

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Bibliographic Details
Published in:Nature materials 2013-08, Vol.12 (8), p.724-728
Main Authors: Parkinson, Gareth S., Novotny, Zbynek, Argentero, Giacomo, Schmid, Michael, Pavelec, Jiří, Kosak, Rukan, Blaha, Peter, Diebold, Ulrike
Format: Article
Language:English
Subjects:
639/301/119/544
639/301/299
639/638/298
639/638/542
Biomaterials
Carbon monoxide
Carbonyl compounds
Catalysts
Coalescence
Condensed Matter Physics
Gases
Iron oxides
letter
Mass transport
Materials Science
Metals
Microscopy
Mobility
Nanotechnology
Optical and Electronic Materials
Sintering
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Summary:Although the coarsening of catalytically active metal clusters can be accelerated by the presence of gases, the role played by gas molecules is difficult to ascertain. Carbon monoxide-induced coalescence of Pd adatoms supported on a Fe 3 O 4 surface is now investigated at room temperature, and Pd-carbonyl species are shown to be responsible for their mobility. The coarsening of catalytically active metal clusters is often accelerated by the presence of gases, but the role played by gas molecules is difficult to ascertain and varies from system to system 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . We use scanning tunnelling microscopy to follow the CO-induced coalescence of Pd adatoms supported on the Fe 3 O 4 (001) surface at room temperature, and find Pd-carbonyl species to be responsible for mobility in this system. Once these reach a critical density, clusters nucleate; subsequent coarsening occurs through cluster diffusion and coalescence. Whereas CO induces the mobility in the Pd/Fe 3 O 4 system, surface hydroxyls have the opposite effect. Pd atoms transported to surface OH groups are no longer susceptible to carbonyl formation and remain isolated. Following the evolution from well-dispersed metal adatoms into clusters, atom-by-atom, allows identification of the key processes that underlie gas-induced mass transport.
ISSN:1476-1122
1476-4660
DOI:10.1038/nmat3667