Tandem Microscopic-Electrochemical Examination of A Charge-Induced Surface Phase Sequence: Ordered Au(110) in Aqueous Iodide Electrolytes as Probed by Potentiodynamic Scanning Tunneling Microscopy.

摘要

Atomic-level structural and dynamical aspects of the electrode potential-induced sequence of surface phases on ordered Au(110) in dilute aqueous alkali iodide electrolytes have been explored by scanning tunneling microscopy (STM) coupled with cyclic voltammetry. This system exhibits a potentially rich series of electro-induced phase transitions triggered primarily by increasing iodide adsorption towards more positive potentials, together with alkali cation coadsorption. Exploration of the real-space phase-transition dynamics, in particular, is facilitated by means of 'potentiodynamic' STM image sequences obtained during potential steps or especially voltammetric sweeps, thereby providing a direct link to conventional (macroscopic) electrochemical phenomena. At the most negative potentials, beyond ca -0.7 V vs SCE, Au(110) forms a largely uniform (1 x 3) phase. The microscopic steps associated with the formation and iodide adsorbate-induced removal of this reconstruction were examined by potentiodynamic STM. In cesium iodide electrolyte, 'one-missing-row' (1 x 3) and (1 x 2) regions are seen to be formed by periodic row displacement en route to the final 'three-missing-row' (1 x 3) phase.