Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 5: Adsorption on semiconductors, oxides and insulators I

O 5.2: Vortrag

Montag, 26. März 2012, 10:45–11:00, MA 042

DFT study of the interaction of hydrogen with stepped ZnO surfaces — •Jakub Goclon and Bernd Meyer — Interdisziplinäres Zentrum für Molekulare Materialien und Computer-Chemie-Centrum, Universität Erlangen-Nürnberg

The nature of the interaction of hydrogen with ZnO surfaces, which is a very important process in heterogeneous catalysis, is still mostly unresolved. While our previous study [1] was devoted to hydrogen adsorption on the ideal ZnO(1010) surface in comparison with experimental observations [2], we will present here results on hydrogen interaction with stepped surfaces. The steps were represented by (1011) and (2021) crystal cuts, considering both Zn and O terminations.

Using DFT calculations in combination with a thermodynamic analysis we have calculated the relative stability of various structural models representing surface steps as function of hydrogen and water chemical potentials. Different surface coverages of hydrogen on O and Zn sites formed by homolytic, heterolytic, and mixed types of adsorption were considered. Based on the phase diagrams from our thermodynamic analysis we find that at low hydrogen chemical potential only OH groups are present, while with increasing hydrogen partial pressure heterolytic adsorption becomes more favorable. For the O-terminated steps the onset of zinc hydroxide formation, which was found to be a stable configuration on the flat ZnO(1010) surface, is observed.

[1] J. Goclon, B. Meyer, in preparation

[2] Y. Wang, B. Meyer, X. Yin, M. Kunat, D. Langenberg, F. Traeger, A. Birkner, Ch. Wöll, Phys. Rev. Lett. 95 (2005) 266104