Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)
O 35.68: Poster
Dienstag, 12. März 2013, 18:15–21:45, Poster B1
Oxidation of graphene on Rh(111) — •Karin Gotterbarm, Wei Zhao, Oliver Höfert, Christian Papp, and Hans-Peter Steinrück — Lehrstuhl für physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91052 Erlangen
We studied the oxidation of graphene sheets grown on a Rh(111) single crystal surface. The graphene was grown by chemical vapor deposition of propylene at 920 K. The growth process and oxidation were studied in-situ by fast XPS performed at the synchrotron facility BESSY II. The lattice mismatch of graphene on the Rh(111) surface induces corrugation of the graphene sheet leading to two separated signals in the C 1s region1. These two signals become most pronounced for graphene layers with a low defect density. The oxidation of graphene was investigated depending on oxygen pressure, temperature and graphene layer quality. We found sigmoidal reaction kinetics indicating the following reaction mechanism: The oxidation starts at defect sites, inducing an induction period. With more free adsorption sites the reaction rate increases until most of the graphene is oxidised. The remaining carbon decays exponentially according to pseudo first order kinetics. The influence of the quality of the graphene layer on the reaction rate supports the assumption that oxidation starts at the defect sites.
1: A. B. Preobrajenski, May Ling Ng, A. S. Vinogradov, N. Mårtensson, Phys. Rev. B 78, 2008, 073401.