On the stability of Ag/Au(111) expanded structures

In this work, we present a series of first-principles calculations on the stability of expanded silver monolayers adsorbed on a gold (111) substrate. The main result obtained is that none of the structures that are more expanded than the (1 x 1) compact monolayer is more stable than the bulk silver phase and hence should not be underpotentially deposited. A possible explanation for the discrepancy between experimental and theoretical results may lie in the strong work function shift generated by the adsorbate. This may produce large electric fields at the interface, modifying the binding energy and promoting anion adsorption through a negative shift in the potential of zero charge.