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O: Fachverband Oberflächenphysik

O 40: Heterogeneous Catalysis: Experiment

O 40.6: Vortrag

Dienstag, 8. März 2016, 15:15–15:30, S053

In situ probing of structural changes in hydrogen activation over ceria/Ru inverse model catalysts — •Jan Ingo Flege¹, Jan Höcker¹, T. Onur Mentes², Alessandro Sala², Andrea Locatelli², Thomas Schmidt¹, Sanjaya D. Senanayake³, and Jens Falta¹ — ¹Institute of Solid State Physics, University of Bremen, Bremen, Germany — ²Sincrotrone Elettra, Trieste, Italy — ³Chemistry Department, Brookhaven National Lab, United States

Ceria is a highly versatile oxide and used in many catalytic applications today; however, its structure-function relation and true active nature in chemical redox reactions are still not well understood. An important example is the interaction of ceria with molecular hydrogen, which is an integral part of the hydrogenation process that produces methanol from CO₂. Here, employing a powerful combination of electron spectromicroscopy with synchrotron radiation, low-energy electron microscopy (LEEM), and micro-illumination diffraction analysis, we follow in situ the complex structural transformations of a well-defined ceria/Ru(0001) model catalyst system when exposed to a reactive H₂ environment [1]. We demonstrate that the transition from CeO₂ to crystalline Ce₂O₃ occurs through a mixture of transient, ordered cerium oxide phases whose average size is on the order of just a few nanometers. Furthermore, these crystalline surface phases are shown to exhibit characteristic intensity-voltage curves in low-energy electron microscopy, which allow their spatial distribution to be imaged in real space directly.

[1] J. Höcker et al., Adv. Mater. Interfaces, in press (2015).