Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 24: Particles and clusters

O 24.5: Talk

Tuesday, March 23, 2010, 11:30–11:45, H34

Molecular Dynamics Studies on the Morphology of PtNi-alloy Particles — •Donato Fantauzzi and Timo Jacob — Ulm University, Albert-Einstein-Allee 47, D-89069 Ulm, Germany

Platinum-based catalysts supported on carbon still serve as the preferred electrocatalyst for the oxygen reduction reaction (ORR), which is one of the most important reactions in basic electrochemistry but also in various applications such as low-temperature polymer electrolyte fuel cells. In order to find a more active catalyst than pure Pt, in the past years various platinum alloys such as PtNi, PtCo, etc. with different atom ratios were synthesized and investigated [1]. Since Pt is limited and rather expensive, these multi-metallic catalysts are not only saving precious metal but also show enhanced reactivity and selectivity.

Motivated by recent experimental work on the morphology of Pt_xNi₁ (x=1,2,3) nanoparticles, we investigated the bulk and surface structure as well as the segregation behavior of differently sized (1.0-3.0 nm) alloy nanoparticles using ReaxFF [2], a reactive molecular dynamics (MD), with a self-optimized forcefield. By applying subsequent simulated annealing cycles to particles of variable size and bulk composition direct comparison to the experimental results was possible [3].

[1] U. A. Paulus et al., J. Phys. Chem. B, 106, 4181 (2002).

[2] A. C. T. van Duin, S. Dasgupta, F. Lorant, W. A. Goddard III.,          J. Phys. Chem. A, 105, 9396 (2001).

[3] E. Favry, D. Wang, D. S. Su, N. Alonso-Vante, D. Fantauzzi,          T. Jacob, to be published.