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O: Fachverband Oberflächenphysik

O 44: Poster Oxides and Insulator Surfaces: Structure, Epitaxy and Growth

O 44.1: Poster

Dienstag, 18. März 2025, 18:00–20:00, P2

The dynamic interaction of size-selected Pt clusters with CeO₂/Rh(111) — •Mina Soltanmohammadi, Johanna Reich, Barbara A.J. Lechner, and Friedrich Esch — Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Germany

Recent studies on Pt clusters supported on ceria have revealed interesting cluster formation and redispersion processes that can be induced by cyclic redox treatments [1]. These catalysts’ activity for combustion is linked to the verge of cluster formation. Here, we investigate the dynamic interaction of size-selected Pt clusters with CeO₂(111) thin films at the atomic scale, using a combination of scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). We present a preparation protocol to obtain highly clean, crystalline and stochiometric CeO₂(111) thin films with extended terraces and well-defined monoatomic steps. Distinct oxygen vacancy distributions are obtained by either annealing in vacuum or reducing in a methanol atmosphere. We then systematically explore the interaction of Pt clusters with the support, particularly the mobility and sintering in dependence of the defect state. The influence of support stoichiometry and the parameters controlling the resulting cluster dispersion are presented. Finally, we present first studies of the Pt dispersion under cyclic oxidizing (O₂) and reducing (methanol) conditions at elevated temperatures, focusing on the resulting cluster configurations at the atomic scale.

[1] Farnesi Camellone et al., ACS Catal. 2022, 4859.

Keywords: size-selected Pt clusters; STM; ceria; redox condition; dispersionn