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O: Fachverband Oberflächenphysik
O 20: Oxides II: Structures, Interactions and Reducibility
O 20.5: Vortrag
Montag, 16. März 2020, 16:45–17:00, WIL B321
High temperature reduction and reoxidation of cerium oxide on Cu(111) — •Linus Pleines1, Lars Buß1,4, Tevfik Onur Menteş2, Francesca Genuzio2, Andrea Locatelli2, Jan Ingo Flege4, and Jens Falta1,3 — 1Institute of Solid State Physics, University of Bremen, Germany — 2ELLETRA Synchrotron Light Source, Basovizza, Italy — 3MAPEX Center for Materials and Processes, Bremen, Germany — 4Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, 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. For the production of methanol from CO2 and H2 oxygen vacancies, e.g. in form of reduced ceria, are necessary. 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 mircoscopy (LEEM) and x-ray absorption spectroscopy (XAS). From earlier studies the orientation of the CeOx is known to be decisive for the catalytic activity. In our experiments both orientations are directly compared via growth of (100) and (111) CeOx islands side by side on the same metal substrate, so that the same conditions prevail during the experiment. At high temperatures, 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 behaviours.