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<p>Graphitic-like ZnO bilayer films deposited on coinage metals, Cu(111), Ag(111), and
Au(111) have been studied by density functional theory calculations including
dispersion corrections. The scope is to compare on an equal footing the properties of the
three systems and in particular the nature of the metal/oxide interface. To this end we
have considered the adsorption of a CO probe molecule and the vibrational shifts
induced by adsorption on ZnO/Cu(111), ZnO/Ag(111), and ZnO/Au(111) compared to
adsorption on the unsupported ZnO bilayer and on the wurtzite ZnO surface.
We find that while the interaction of ZnO with Ag and Au supports is dominated by
dispersion interactions with little or no charge transfer at the interface, in the case of Cu
a moderate electron transfer occurs towards the ZnO bilayer. As a consequence, while
the stretching frequency of CO on ZnO/Au is blue-shifted, that on ZnO/Cu is red-
shifted compared to free CO. CO on ZnO/Ag is intermediate. In all three cases,
however, the ZnO bilayer is almost flat, with a modest rumpling found in the case of Cu
as a consequence of the stronger chemical interaction. The results fully explain the CO
vibrational shifts of CO on ZnO/Cu(111) [Schott, V. et al. Angew. Chem. Int. Ed. 2013,
52, 1-6] without implying major distortions in the supported film.
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