Kinetics of copper UPD on stepped platinum single crystals in the presence of acetonitrile

The kinetics of copper underpotential deposition on stepped Pt(h k l) electrodes with controlled width of (1 1 1) terraces in acidic solutions of copper sulfate with 0–200 mM of acetonitrile (AcN) has been studied by means of cyclic voltammetry. In the presence of AcN Cu UPD process is hindered both at (1 0 0) steps and (1 1 1) terraces of Pt(17 15 15) and Pt(7 5 5) faces due to blocking of the electrode surface with organic molecules, strongly adsorbed at the steps and nearby ones. The decoration of (1 1 0) steps with copper adatoms is slightly accelerated for Pt(7 7 5) electrode in the solution with 0.04 mM AcN. Increase in AcN concentration leads to inhibition of the UPD process. The difference in behavior of the stepped platinum electrodes is controlled by competitive adsorption of AcN, (bi)sulfate and Cu atoms at the step sites. AcN adsorption at (1 0 0) steps is stronger as compared with (1 1 0) ones.