Atomic Resolution Observation of a Size-Dependent Change in the Ripening Modes of Mass-Selected Au Nanoclusters Involved in CO Oxidation.
J Am Chem Soc
; 137(48): 15161-8, 2015 Dec 09.
Article
em En
| MEDLINE
| ID: mdl-26544914
ABSTRACT
Identifying the ripening modes of supported metal nanoparticles used in heterogeneous catalysis can provide important insights into the mechanisms that lead to sintering. We report the observation of a crossover from Smoluchowski to Ostwald ripening, under realistic reaction conditions, for monomodal populations of precisely defined gold particles in the nanometer size range, as a function of decreasing particle size. We study the effects of the CO oxidation reaction on the size distributions and atomic structures of mass-selected Au(561±13), Au(923±20) and Au(2057±45) clusters supported on amorphous carbon films. Under the same conditions, Au(561±13) and Au(923±20) clusters are found to exhibit Ostwald ripening, whereas Au(2057±45) ripens through cluster diffusion and coalescence only (Smoluchowski ripening). The Ostwald ripening is not activated by thermal annealing or heating in O2 alone.
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MEDLINE
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En
Ano de publicação:
2015
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Article