Underpotential deposition of copper in acetonitrile

Underpotential deposition (upd) of Cu in acetonitrile solutions on textured Au{111}, polycrystalline Au (poly-Au) and polycrystalline Pt (poly-Pt) electrodes is shown for the first time. Formation of the upd layer on Au proceeds in two stages. The kinetics of formation of the upd layer are faster and better defined on Au{111} compared to poly-Au electrode. Cu upd from acetonitrile solutions containing Cu(II) or Cu(I) ions proceeds through similar stages, but showing differences in kinetics and potential regions. Formation of the Cu upd layer on poly-Pt in acetonitrile indicates restructuring of the electrode. The transition from upd to bulk deposition (opd) occurs on Au{111} electrodes after formation of ∼one upd monolayer, while on poly-Au and poly-Pt electrodes the respective coverages are ∼two monolayers and ∼1.5 monolayers of upd Cu before the upd–opd transition. With all the metal electrodes (Au{111}, poly-Au and poly-Pt) the evolution of the cyclic voltammetry during the upd–opd transition is consistent with the deposition of bulk Cu on top of a upd layer, i.e. a Stranski–Krastanov mechanism.