Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 16: Heterogeneous Catalysis: Theory
O 16.3: Vortrag
Montag, 12. März 2018, 15:30–15:45, MA 141
Steps and catalytic reactions: First-principles Kinetic Monte Carlo study on CO oxidation with preadsorbed O on Rh (553) — •Baochang Wang1, Chu Zhang2, Johan Gustafson2, and Anders Hellman1 — 1Department of Physics and the Competence Centre for Catalysis, Chalmers University of Technology, 41296, Sweden — 2Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund, Sweden
Many catalytic reactions display strong structure sensitivity, and particular steps and defects are often identified as active sites for the reactions at hand. A controlled way to address this is to use vicinal surfaces where the step density is known. Here we studied the CO oxidation reaction on oxidized Rh(111) and Rh(553) by first-principles methods coupled with Kinetic Monte Carlo (KMC) to provide insight to the structure sensitivity on Rh. Our recent experiment shows that the reaction between CO and preadsorbed O proceeds at lower temperature on a stepped Rh(553) surface than on a flat Rh(111), indicating that stepped surfaces are more catalytically active. After removing half of the oxygen, however, the reaction slows down significantly and the O coverage seem to remain as 25% of the initial coverage. First-principles calculations were performed to investigate the different possible reaction pathways on the surfaces. A lattice KMC model was built based on the calculated barriers. We do, however, find that this is not thanks to reactions on the steps, but rather on the terraces close to the steps. Our theory results are compared to experimental data, both concerning the CO activity but also core-level spectroscopy.