Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 7: Surface reactions I

O 7.5: Vortrag

Montag, 27. März 2006, 12:15–12:30, WIL C207

Copper Dissolution Reaction (CDR) in the Presence of a Binary 2D-Compound: CuI on Cu(100) — •Minh Hai Nguyen Thi, Peter Broekmann, and Klaus Wandelt — Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerst. 12, D-53115 Bonn

The anodic copper dissolution reaction (CDR), has been studied by means of Cyclic Voltammetry (CV) and in-situ scanning tunnelling microscopy (STM) at the electrochemical solid/liquid interface. Exposing the Cu(100) electrode surface to an acidic and iodide containing electrolyte (5 mM H2SO4, 1 mM KI) leads to the formation of an electrocompressible/decompressible c(p x 2)-I adsorbate layer at potentials close to the onset of the CDR. At these positive potentials mobile CuI species originating mainly from step-edges cause the local exceeding of the CuI solubility product, thereby giving rise to the nucleation and growth of a laterally well ordered 2D-CuI film. As this process occurs at potentials well below the potential regime of the 3D-CuI bulk formation we refer to it as under potential formation (UPF) of a binary compound. The formed 2D-CuI film exhibits symmetry properties and nearest neighbour distances that are similar to the (111) lattice of the crystalline bulk CuI phase (zinc blende type). Surprisingly, the 2D-CuI film on Cu(100) does not act as a passivation layer against the copper dissolution which proceeds via an inverse step flow mechanism.