Formation of copper adatom layers on polycrystalline platinum: The surfaceactivation mechanism

Formation of adatom layers of copper on polycrystalline platinum in 0.5 M H 2SO4 + 0.01 M CuSO4 and 0.5 M HClO4 + 0.01 M Cu(ClO4)(2) is studied by chro noamperometry and cyclic voltammetry. The deposition rate is shown to essen tially depend on the electrode pretreatment. Potentiostatic polarization ac tivates the platinum surface with respect to the copper adlayer formation, with the activation mechanism depending on the polarization potential. Near the equilibrium potential of copper (0.24-0.35 V), two-dimensional phase C u(1 x 1) grows and a three-dimensional microdeposit forms. At 0.7-3.8 V, co pper oxides and hydroxides form; these are active centers of a two-dimensio nal growth of a monolayer of adatoms at more negative potentials.