Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.56: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Methanol synthesis on ZnO(00011): CO reduction at oxygen vacancies. — •Johannes Frenzel, Nora Graf, and Dominik Marx — Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany

In the heterogeneous catalytic synthesis of methanol on the ZnO(0001) surface with oxygen vacancies [1] gives rise to a complex free energy landscape[2] for the reduction of CO on this catalyst at high temperature and pressure conditions as required in the industrial process. Using ab initio metadynamics for computational heterogeneous catalysis the underlying complex reaction network from CO to methanol has been generated in the first place by exploring the global free energy, that allowed a subsequent refinement of individual reaction pathways.[2]

In the present study, the complex reduction process from CO to methanol is studied by exploring the electronic structure of reaction intermediates with density functional theory. After comparing the electronic bands and molecular orbitals involved we find the reduction state of surface and O vacancy bound adsorbates to be controlled by the charge states of the F–center, which is defined by the gas phase conditions.[1] Monitoring the reduction process of reaction paths obtained by metadynamics sampling of the free energy surface at the electronic structure level on snapshots reaction allows further mechanistic insight into the catalytic process.

[1] Kiss, Witt, Meyer and Marx, J. Chem. Phys. 130 (2009) 184706

[2] Kiss, Frenzel, Nair, Meyer and Marx, J. Chem. Phys. 134 (2011) 064710