Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 16: Heterogeneous Catalysis: Theory
O 16.2: Vortrag
Montag, 12. März 2018, 15:15–15:30, MA 141
Insights into the Relative Importance of Ripening and Particle Migration for Sintering of Pt Nanoparticles — •Elisabeth Dietze1, Frank Abild-Pedersen2, and Philipp N. Plessow1 — 1Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany — 2SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Stanford, USA
A rational approach to improve the stability of heterogeneous transition metal catalysts requires to understand deactivation mechanisms on an atomic scale. For Pt nanoparticles, simulations have shown that ripening through the gas phase via volatile PtO2 is relevant for sintering [1], but surface migration could not be excluded as an alternative mechanism. Recently, the migration of Pt particles was modeled from first principles [2] and diffusion constants were extracted. Using these diffusion constants, the importance of particle migration for sintering can now be estimated. To model the position and migration of particles, we use a kinetic Monte Carlo rather than a mean field model. This also allows us to explicitly study the effect of defects. The developed approach is able to simulate both ripening and particle migration and one can therefore compare the relative importance of these two mechanisms. We furthermore investigate how temperature, partial pressure of oxygen, binding strength of defects and the shape of the PSD influence the sintering kinetics.
References: [1] Plessow, P. N.; Abild-Pedersen, F., ACS Catal. 2016, 6 (10). [2] Li, L., et al. J. Phys. Chem. C 2017, 121(8).