Effect of Chloride Anions on Cu Electrodeposition onto Pt(110) and Pd(110) Surfaces*

Cyclic voltammetry for Cu UPD on Pd(110) in H2S04, HC104 and in Cl containing solutions has been studied in comparion with Cu UPD on a Pt(l10) surface. The structural properties of Pd(110) and Pt(110) after Cu UPD in different electrolyte solutions were investigated by LEED. RHEED and Auger electron spectroscopy. Structural models for Pd(110) covered by 1 and 2 ML Cu, derived from the coulometric charge, AES measure-ments and the diffraction data are presented. Specific adsorption of S042-/HS04- anions causes the formation of ordered c(2X4) and c(2x2) structures on Pt(110) and Pd(1l0) respectively. In the presence of chloride ions, specific adsorption of Cl on the Cu/Pd(l10) surface gives rise to a pronounced change in the voltammogram and results in two ordered superstructures, while on Pt(l10) no specific adsorption of Cl takes place