title: Atomic Resolution Observation of a Size-Dependent Change in the Ripening Modes of Mass-Selected Au Nanoclusters Involved in CO Oxidation.
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.
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham , Birmingham, B15 2TT, U.K.
authors.forename: Kuo-Juei
authors.initials: KJ
authors.lastname: Hu
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham , Birmingham, B15 2TT, U.K.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Plant
authors.affiliation: Johnson Matthey Technology Centre , Blounts Court Road, Sonning Common, Reading, RG4 9NH, U.K.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ellis
authors.affiliation: Johnson Matthey Technology Centre , Blounts Court Road, Sonning Common, Reading, RG4 9NH, U.K.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Brown
authors.affiliation: Johnson Matthey Technology Centre , Blounts Court Road, Sonning Common, Reading, RG4 9NH, U.K.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Bishop
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham , Birmingham, B15 2TT, U.K.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Palmer