Copper UPD on selenium-modified polycrystalline Pt electrode

Underpotential deposition of Cu onto an Se-modified smooth polycrystalline Pt electrode in an acidic CuSO4 solution was investigated using a cyclic voltammetry. It was obtained that the specific voltammetric pattern of Cu UPD observed for a clean Pt electrode disappeared and a new current peak at potentials much closer to bulk Cu deposition was formed. This feature of a cyclic voltammogram is similar to that observed earlier for clean Pt electrode in acidic CuSO4 solutions containing selenite and also to that described for S-modified Pt electrode in an additive-free CuSO4 solution. The reasons for the difference in the voltammetric behavior of bare Pt and Se-modified Pt in the potential range characteristic of Cu UPD were considered. A model of Cu deposition taking place onto the free Pt sites at more positive potentials and onto the Se-covered ones at less positive potentials was discussed with closer scrutiny.