Kinetic model for sintering of supported metal particles with improved size-dependent energetics and applications to Au on
- 31 January 2007
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 75 (3), 035430
- https://doi.org/10.1103/physrevb.75.035430
Abstract
A kinetic model for the sintering of metal particles on oxide or other support surfaces is derived and applied to simulate experimental measurements of the sintering of a model gold catalyst: gold nanoparticles supported on . It follows the pioneering work of Wynblatt and Gjostein (WG), Progress in Solid State Chemistry (1975, p. 21), but removes several important assumptions that create dramatic errors in sintering rates for particles smaller than in diameter, including (1) use of the Gibbs-Thomson relation assuming that the surface free energy of metal particles is independent of size, and (2) neglect of all but the first-order terms in a Taylor series expansion. Recent microcalorimetry measurements have shown these assumptions to be untrue in that metal particles smaller than have much higher surface free energies than large particles. A modified bond-additivity model more accurately estimates particle energy versus size. This estimate was incorporated into the kinetic model of WG and applied to simulate the sintering of Au particles on as measured by temperature-programmed low-energy ion scattering. Our model reproduces well the broad temperature range over which sintering typically occurs in such experiments. This is analogous to accurate modeling of long-term sintering kinetics of metal nanoparticles under the isothermal conditions of real catalysis. These results also highlight problems with classical methods for determining the sintering mechanism based solely upon the shape of the sintered particle-size distribution.
Keywords
This publication has 69 references indexed in Scilit:
- Particle size distributions in heterogeneous catalysts: What do they tell us about the sintering mechanism?Catalysis Today, 2005
- Small Pd Clusters, up to the Tetramer At Least, Are Highly Mobile on the MgO(100) SurfacePhysical Review Letters, 2005
- Thermal Stability of Au Nanoparticles in O2 and Air on Fully Oxidized TiO2(110) Substrates at Elevated Pressures. An AFM/XPS Study of Au/TiO2 Model SystemsThe Journal of Physical Chemistry B, 2004
- Sintering of Ni/Al2O3 catalysts studied by anomalous small angle X-ray scatteringApplied Catalysis A: General, 2004
- In situ scanning tunneling microscopy of oxide-supported metal clusters: Nucleation, growth, and thermal evolution of individual particlesThe Chemical Record, 2002
- The Effect of Size-Dependent Nanoparticle Energetics on Catalyst SinteringScience, 2002
- Structure–reactivity correlations for oxide-supported metal catalysts: new perspectives from STMJournal of Molecular Catalysis A: Chemical, 2000
- On the Compact Structure of Small fcc Metal ClustersJournal of Catalysis, 1994
- Surface area stabilization of Ir/Al2O3 catalysts by CaO, SrO, and BaO under oxygen atmospheres: Implications on the mechanism of catalyst sintering and redispersionJournal of Catalysis, 1978
- Statistical model for coalescence of islands in discontinuous filmsApplied Physics Letters, 1975