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O: Fachverband Oberflächenphysik

O 67: Poster: Oxide, Insulator and Semiconductor Surfaces

O 67.1: Poster

Mittwoch, 20. März 2024, 18:00–20:00, Poster C

DFT study of the adsorption of small molecules on a vicinal ZnO surface — •Marlene Sell and Bernd Meyer — Interdisciplinary Center for Molecular Materials and Computer Chemistry Center, FAU Erlangen-Nürnberg, Germany

Understanding the adsorption of reactants on the surface of a catalyst is not only of interest for exploring reaction mechanisms, but the adsorption itself can also alter the structure of the catalyst surface.

In this study, the adsorption of carbon dioxide, formaldehyde, and formic acid, three important intermediates in the synthesis of methanol from syngas, on the vicinal ZnO(1014) surface was investigated using density-functional theory (DFT). Four different structures of the surface were considered: two previously proposed truncated bulk terminations, both include 2-fold coordinated surface atoms, and two new structural model, which are found to be lower in energy due to the elimination of the 2-fold coordinated atoms by a shift of atomic rows. For each of the three molecules and four surface models, the energetically most favorable structure was determined and characterized by calculation of the XPS core level shifts.

In addition, the stabilization of the different surface models by a successively increasing number of water molecules was compared. The resulting adsorption energies show that once water molecules adsorb on the undercoordinated Zn surface atoms, the bulk-truncated surface structure becomes energetically more favorable than the structure with shifted atomic rows.

Keywords: zinc oxide surfaces; adsorption of small molecules; XPS core level shifts; DFT calculations