A theoretical study of Zn adsorption and desorption on a Pd(111) substrate

The adsorption and structure of Zn on a Pd(111) surface has been investigated using density functional theory (DFT). It could be shown that Zn prefers adsorption sites with a maximum amount of Pd neighbours on the Pd(111) surface. Zn does form a stable PdZn surface alloy on Pd(111) which shows a (2 × 1) structure. The surface energy of this surface alloy decreases with increasing numbers of PdZn layers. Furthermore the adsorption of Zn on the PdZn surface alloy was investigated. The electronic structure of the Zn layers approaches the bulk Zn state only after a thickness of 4 additional Zn layers. A clear charge transfer between Pd and Zn has been found and the electronic structure of the Zn suggests an anisotropic binding of the Zn, with higher binding energy within a Zn layer and lower binding energy between two Zn layers. This is also reflected in the different desorption energies of different Zn layers found in experiments.