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O: Fachverband Oberflächenphysik

O 81: Heterogeneous Catalysis III

O 81.6: Vortrag

Donnerstag, 20. März 2025, 11:45–12:00, H6

Reducibility of Sm-doped ceria islands on Ru(0001) — •Raquel Sanchez-Barquilla, Rudi Tschammer, Lars Buss, Carlos Morales, and Jan Ingo Flege — Applied Physics and Semiconductor Spectroscopy, BTU Cottbus-Senftenberg, Germany

The interaction between metal and oxide is critical when considering the hydrogenation of CO₂ to hydrocarbons. In this context, the inverse oxide/metal catalysis architecture allows for achieving better catalytic performance due to strong oxide-metal interactions. In particular, in cerium-based inverse catalyst systems, the Ce³⁺ cations have been demonstrated to play an active role in methanol synthesis, suggesting that the activity can be enhanced by promoting those through alloying with trivalent, catalytically active rare-earth metals, such as Sm. Here, we present a low-energy and X-ray photoemission electron microscopy (LEEM/XPEEM) investigation that shows how the reducibility of CeO₂(111) islands on Ru(0001) is highly enhanced when doped with Sm. After post-annealing with Sm, intensity-voltage (I-V) LEEM curves show an immediate reduction of the islands at the surface. Exposure to low H₂ pressures efficiently reduces the islands to a (3×3) superstructure formed by ordered oxygen vacancies, as evidenced by characteristic IV-LEEM spectra and low-energy electron diffraction patterns. Furthermore, annealing at high temperatures shows the further reduction of the Sm-ceria islands, with features characteristic of the hexagonal Ce₂O₃(0001) phase. While this reduction takes about one hour for pure ceria, this transition is virtually immediate for the Sm-doped ceria islands at comparable conditions.

Keywords: Ceria; Samaria; LEEM; Structure