Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 69: Surface Reactions and Heterogeneous Catalysis 2

O 69.10: Vortrag

Donnerstag, 8. September 2022, 17:30–17:45, H4

In-situ characterization of cyclic reduction and reoxidation of CeOx(111) and CeOx(100) islands on Cu(111) — •Linus Pleines1, Lars Buß2, Tevfik Onur Menteş3, Francesca Genuzio3, Andrea Locatelli3, Jens Falta1,4, and Jan Ingo Flege21Institute of Solid State Physics, University of Bremen, Germany — 2Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, Germany — 3Elettra-Sincrotrone Trieste S.C.p.A., Basovizza Trieste, Italy — 4MAPEX Center for Materials and Processes, Bremen, Germany

Cerium oxide (CeOx) is of special interest due to its catalytic activity and various other electronic and optical applications. The inverse model catalyst CeOx on Cu(111) has a high activity for methanol synthesis from H2 and CO2. For the activation of CO2, Ce3+ sites have to be present at the surface, which means that the CeOx has to be reduced to some extent. This may be achieved by exposure to H2 at elevated temperatures. We studied the interaction of H2 and CO2 with CeOx islands on Cu(111) with low-energy electron microscopy (LEEM) and X-ray absorption spectroscopy (XAS). From earlier studies, the orientation of the CeOx is known to be decisive for its catalytic activity. In our experiments (100) and (111) CeOx islands are grown side by side on the metal substrate, so that identical reaction conditions prevail during the experiment. At a high temperature of 550 C, exposure to H2 leads to partial reduction, and exposure to CO2 leads to reoxidation of the CeOx. The differences observed for the two island orientations regarding structure and composition will be discussed.

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