Pt-Zn Clusters on Stoichiometric MgO(100) and TiO2(110): Dramatically Different Sintering Behavior

Journal Article · Mon Mar 02 04:00:00 EST 2015 · Journal of Physical Chemistry C, 119(11):6047-6055

DOI:https://doi.org/10.1021/jp512277x· OSTI ID:1222063

Dadras, Mostafa J.; Shen, Lu; Alexandrova, Anastassia N.

Zn was suggested to be a promising additive to Pt in the catalysis of dehydrogenation reactions. In this work, mixed Pt-Zn clusters deposited on two simple oxides, MgO(100) and TiO2(110), were investigated. The stability of these systems against cluster sintering, one of the major mechanisms of catalyst deactivation, is simulated using a Metropolis Monte Carlo scheme under the assumption of the Ostwald ripening mechanism. Particle migration, association to and dissociation from clusters, and evaporation and redeposition of monomers were all included in the simulations. Simulations are done at several high temperatures relevant to reactions of catalytic dehydrogenation. The effect of temperature is included via both the Metropolis algorithm and the Boltzmann-weighted populations of the global and thermally accessible local minima on the density functional theory potential energy surfaces of clusters of all sizes and compositions up to tetramers. On both surfaces, clusters are shown to sinter quite rapidly. However, the resultant compositions of the clusters most resistant to sintering are quite different on the two supports. On TiO2(110), Pt and Zn appear to phase separate, preferentially forming clusters rich in just one or the other metal. On MgO(100), Pt and Zn remain well-mixed and form a range of bimetallic clusters of various compositions that appear relatively stable. However, Zn is more easily lost from MgO through evaporation. These phenomena were rationalized by several means of chemical bonding analysis.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1222063
• Journal Information: Journal of Physical Chemistry C, 119(11):6047-6055, Journal Name: Journal of Physical Chemistry C, 119(11):6047-6055
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory