SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 74: Poster Session VI: Oxide and insulator surfaces: Structure, epitaxy and growth II

O 74.7: Poster

Mittwoch, 3. März 2021, 13:30–15:30, P

High temperature reduction and reoxidation of cerium oxide on Cu(111) — •Linus Pleines¹, Lars Buss^1,2, Tevfik Onur Menteş³, Francesca Genuzio³, Andrea Locatelli³, Jan Ingo Flege², and Jens Falta^1,4 — ¹Institute of Solid State Physics, University of Bremen, Germany — ²Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, Germany — ³ELLETRA Synchrotron Light Source, Basovizza, Italy — ⁴MAPEX Center for Materials and Processes, Bremen, Germany

Cerium oxide is of great interest due to its technological importance in various electronic, optical and catalytic applications. The inverse model catalyst cerium oxide on Cu(111) shows a high activity for the production of methanol. Oxygen vacancies, e.g. in form of reduced ceria, are necessary for the production of methanol from CO₂ and H₂. The reduction of ceria may be achieved by exposure to H₂ at elevated temperatures. We studied the interaction of H₂ and CO₂ with cerium oxide islands on a Cu(111) substrate with low-energy electron microscopy (LEEM) and x-ray absorption spectroscopy (XAS). From earlier studies, the orientation of the cerium oxide is known to be decisive for the catalytic activity. In our experiments, the impact of both orientations are directly compared via growth of (100) and (111) cerium oxide islands side by side. At temperatures around 550 ^∘C, exposure to H₂ leads to partial reduction and exposure to CO₂ leads to complete reoxidation of the cerium oxide. The (100) and (111) orientations show different reduction and reoxidation behaviors.