Gold nanostructures on TiOx/Mo(112) thin films

The structure and composition of Au nanostructures deposited on TiOx/Mo(112) films has been investigated based on first principles DFT calculations. The aim of the calculations is to identify plausible candidates for the structures generated under experimental conditions in the growth of Au/TiOx/Mo(112) films. To this end, both static and molecular dynamics (MD) calculations have been performed. Various Au coverages have been considered, low (below monolayer), medium (monolayer), and high (bilayer) coverages. An ab initio thermodynamic analysis shows that, at the experimental temperature and oxygen partial pressure, the An monolayer forms a (1 x 1) Au/TiO3/Mo(112) structure. On the basis of the comparison of the computed and experimental valence bands, phonon spectra, and STM images, we propose a tentative assignment to a structure where Au chains are formed at the interface between the Mo support and the TiO3 film. The additional deposition of An results in the formation of a bilayer (1 x 3) Au/TiO3/Mo (112) structure. Here, we observe the tendency for gold to aggregate and form nanowires with half of the Au atoms in contact with the TiO3/ Mo(112) support and the rest forming a second layer. The top and bottom An layers of the nanowire exhibit a different chemical nature.