Does Pb underpotential deposition rearrange surface-near atoms in AgAu films and nanoparticles?

Bimetallic surfaces consisting of Ag and Au in various ratios, as sputtered thin films as well as wet-chemically synthesised nanoparticles were modified by underpotential deposition of Pb (Pb-UPD). On the basis of characteristic voltametric peaks along with supporting DFT calculations we conclude that depositing Pb on the Ag-rich surfaces induces a swap of Ag atoms with underlying Au atoms to form a Au-rich layer in the presence of the Pb monolayer. Our experiments showed that Pb-UPD is a powerful tool not only to probe the surface composition and structure but to change the arrangement of surface atoms in binary alloys.