Underpotential Deposition of Lead on Copper(111): A Study Using a Single-Crystal Rotating Ring Disk Electrode and ex Situ Low-Energy Electron Difrraction and Auger Electron Spectroscopy

The underpotential deposition of Pb was studied on Cu(111) single crystal surfaces prepared both by a novel electropolishing procedure and by sputtering/annealing in ultrahigh vacuum. Identical results were found with both methods. Pb atoms are deposited underpotentially on Cu(lll) into a compact nonrotated hexagonal overlayer. The measured Pb coverage at saturation is 53% with respect to the Cu(lll) substrate and is identical to the packing density of the (111) plane of bulk Pb. The presence of Cl- in the supporting electrolyte has a strong effect on the potential region where deposition/stripping occuss and on the reversibility of the reaction.