The underpotential deposition of lead on gold has been studied by cyclic voltammetry and UV-visible differential reflectance spectroscopy. Comparative experiments were carried out with a polycrystalline gold electrode and two single-crystal gold electrodes with the orientations (111) and (210). For the single crystal surfaces, the reflectance results confirm the large effect of the crystallographic orientation on the deposition and redissolution of lead on gold surfaces. The existence of different types of structures for adsorbed lead, depending not only on the atomic distribution of the substrate but above all on the electrode potential, is demonstrated. An attempt is made to explain the behavior of polycrystalline gold on the basis of the results obtained for the two investigated gold single crystal faces.
underpotential deposition; gold single crystals; spectroelectrochemistry; UV-visible differential reflectance spectroscopy
