Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 9: Surface Chemical Reactions and Heterogeneous Catalysis I
O 9.1: Vortrag
Montag, 31. März 2014, 10:30–10:45, PHY C 213
In-situ investigation of the growth and oxidation of Mo2C/Mo(100) using high-resolution X-ray photoelectron spectroscopy — •Udo Bauer, Christoph Gleichwald, Christian Papp, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen
Molybdenum carbide has been proposed as a noble metal free catalyst for a variety of reactions. We used our supersonic molecular beam setup to carburize a Mo(100) single crystal. Ethylene adsorption at 900 K and subsequent oxidation of the carburized system at 1200 K were followed in-situ in the C 1s and Mo 3d core levels by fast X-ray photoelectron spectroscopy (XPS) performed at the synchrotron facility BESSSY II. We observed three different species in the C 1s core level during the C2H4 deposition. Starting with the growth of a precursor carbide, surface and bulk carbide species arise and saturate after an exposure of 1200 L. Subsequent annealing to 1300 K removed excess carbon, resulting in the desired Mo2C stoichiometry. Oxidation of the molybdenum carbide revealed a very fast diffusion of bulk carbon to the surface, refilling empty sites occurring due to CO desorption.