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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.28: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

First-principles study of the interaction of CO, CO₂ and water with NiO surfaces — •Tobias Schaub, Volker Strauss, and Bernd Meyer — Interdisziplinäres Zentrum für Molekulare Materialien ICMM, Universität Erlangen-Nürnberg

Nickel oxide is an important catalyst for the cracking and partial oxidation of hydrocarbons. Under reaction conditions CO, CO₂ and water are frequently present in the gas phase. The formation of carbonates and the partial hydroxylation of the NiO surfaces, however, often leads to a reduction of the catalytic activity of NiO due to a blocking of available surface sites for the hydrocarbon reactions. To elucidate the nature and stability of the surface carbonates and hydroxyl groups we have used DFT+U calculations to study the adsorption of CO, CO₂ and water on different structural models of ideal and defective NiO surfaces. We find that undercoordinated Ni sites activate CO₂ and stable surface carbonates are formed which are bound in a tridentate configuration, similar as previously observed for ZnO [1]. Water adsorbs molecularly or dissociatively, depending on the surface sites with a similar binding energy as CO₂. Therefore, a strong competition between CO₂ and water for the low coordinated Ni surface sites can be expected. Finally, the influence of O vacancies on the adsorption of CO, CO₂ and water will be discussed.

[1] Y. Wang et al. Angew. Chem. Int. Ed. 46 (2007) 5624