Underpotential deposition of cadmium onto (111) face of silver from chloride containing solution

Abstract

The underpotential deposition (UPD) of cadmium and Ag–Cd alloy formation on the (111) face of silver in chloride containing solutions were investigated by cyclic voltammetry and the potentiostatic pulse technique. It was shown that the UPD of cadmium commences at about −400 mV versus SCE (300 mV vs. Cd 2+/Cd) with the formation of ordered structure of the type ( 3 x 3 ) R30°. Chloride adatoms, which are adsorbed on the silver substrate when UPD of Cd starts, do not desorb. They become replaced by Cd adatoms and remain adsorbed and discharged on top of a Cd layer. At potentials close to the reversible potential of Cd alloying of Ag with Cd takes place, being expressed by two sharp cathodic peaks on the voltammograms.