Abstract
We
report a systematic comparative dispersion-corrected DFT study of
single (K, Au, and Pt) atoms adsorption over a wide range of
metal-supported oxide ultrathin films (MgO on Ag and Mo, ZnO on Cu, Ag,
and Au, SiO2 on Pt and Ru, TiO2 on Ag and Pt, ZrO2 on Pt and ZrPt).
These films include reducible and non-reducible oxides, and have been
prepared and characterized experimentally, showing very unusual and
interesting behaviour towards metal atoms adsorption.
The interaction of
K and Au with the metal/oxide substrates is dominated by
charge-transfer aspects, where K tends to assume positive charge and Au
negative charge.
This fact reflects into a general trend where
metal-supported oxide films displaying large work function (i.e. deep
empty states) tend to bind K cations strongly, while supports with small
work function (i.e. shallow donor
states) strongly stabilize Au in
anionic form.
The correlation between adsorption energy and work
function is not strong enough to neglect several other aspects related
to chemical and morphological properties of the specific oxide/metal
interface. The case of Pt is completely different: here, covalent
contributions to the bonding prevail, and the bond strength depends on
factors such as the surface morphology and local atomic coordination,
rather than the support’s work function.
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