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O: Fachverband Oberflächenphysik
O 52: Oxide and insulator surfaces: Structure, epitaxy and growth I
O 52.2: Vortrag
Dienstag, 10. März 2026, 15:00–15:15, WILL/A317
Segregation effects in 2D mixed oxide nano-islands: edge structure and composition in V(2-x)FexO3 monolayer islands — Ying Wang1, Piotr Igor Wemhoff1, Ghada Missaoui1, Niklas Nilius1, Jacek Goniakowski2, and •Claudine Noguera2 — 1Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany — 2CNRS-Sorbonne Université, Institut des Nanosciences de Paris, Paris, France
Low-coordinated atoms located at the surface or edges of oxide nanostructures play a crucial role in adsorption and reaction processes in heterogeneous catalysis. Contrary to binary compounds, there is a significant lack of information on their nature and behavior available for ternary materials. In this study, high-resolution scanning tunneling microscopy, DFT calculations and Monte Carlo simulations have been used to decipher the edge structure and composition of mixed V(2-x)FexO3 honeycomb monolayer islands grown on Pt(111).
DFT calculations and MC simulations demonstrate that, in contrast to a clear preference for VO-terminated edges in the pure V2O3 system, Fe segregation to the edges of mixed films tends to produce undercoordinated edge Fe cations, with a ratio of Fe/VO edge species highly sensitive to the oxygen environment. We show that the different oxygen affinity of V and Fe cations, yielding different bonding strengths of terminal vanadyl and ferryl groups are the main cause of the segregation pattern. The sensitivity of edge composition to the oxygen environment thus represents a lever for manipulating the edge configurations and tuning their catalytic response.
Keywords: 2D oxide islands; oxide alloys; segregation; edge structure; cation mixing