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O: Fachverband Oberflächenphysik
O 52: Oxide and insulator surfaces: Structure, epitaxy and growth I
O 52.1: Hauptvortrag
Dienstag, 10. März 2026, 14:30–15:00, WILL/A317
Dynamics of catalytically active, atomically precise clusters on reducible oxide supports under the (fast) scanning tunneling microscope — •Friedrich Esch — TU Munich, Garching, Germany
Reducible oxides are versatile supports for catalytically active particles. Their reducibility offers the possibility to steer fundamental properties such as cluster stability and shape, charge transfer, lattice oxygen reverse spillover, or encapsulation. In this talk, I present our fundamental studies on the dynamics of atomically precise Pt clusters on two complementary supports, Fe3O4(001), where reduction leads to interstitial diffusion and hole formation, and CeO2(111), where it leads instead to the formation of surface-near vacancies. As a local probe, we employ scanning tunneling microscopy (STM) at elevated temperatures and under reactive gas environments, upgraded with sophisticated tools for fast movie acquisition and cluster tracking. We complement this structural characterization with integral pulsed valve molecular beam "sniffer" activity and x-ray photoemission measurements. While on magnetite stabilization of even very small clusters via encapsulation is observed [1,2], on ceria, a dimensionality crossover from 3D to 2D clusters occurs, triggered by the degree of surface reduction [3].
[1] S. Kaiser et al., ACS Catal. 11 (2021) 9519.
[2] S. Kaiser et al., ACS Catal. 13 (2023) 6203.
[3] J. Reich et al., ACS Catal. 15 (2025) 18369.
Keywords: clusters; ceria; magnetite; encapsulation; fast STM