Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Heterogeneous Catalysis II
O 41.2: Vortrag
Dienstag, 18. März 2025, 14:15–14:30, H8
Size-dependent nanoparticle sintering under catalytic reaction conditions — •Thomas Florian Keller1,2, Christoph Seitz1, Henning Runge1, Vedran Vonk1, and Andreas Stierle1,2 — 1Centre for X-ray and Nano Science CXNS, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — 2University of Hamburg, Department of Physics, Hamburg, Germany
Catalytic metal nanoparticles applied in heterogeneous gas phase catalysis are known to change their shape during the conversion. We elucidate the evolution of the height to diameter aspect ratios of a substantial number of PtRh alloy nanoparticles exposed to mild and harsh catalytic CO oxidation reaction conditions by correlative atomic force- and scanning electron-microscopy. The preferentially (111) oriented Pt rich nanoparticles supported on a (0001) Al2O3 single crystal surface were imaged as grown and after the exposure to the catalytic conditions. We utilized an image-registration based approach combined with one-by-one nanoparticle correlation to overcome single nanoparticle studies and ensemble averages. This approach permitted us to shed light onto the active size dependent sintering mechanism as e.g., particle migration and coalescence, and Ostwald ripening. While for mild catalytic conditions the aspect ratio is rather independent of the lateral nanoparticle size, for harsh conditions particles above an initial threshold diameter of around 45 nm tend to extraordinary grow on the cost of the surrounding smaller particles.
Keywords: correlative microscopy; image registration; scanning force microscopy; scanning electron microscopy