A 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
PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY
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Atomic-level structural and dynamical aspects of the electrode potential-induced sequence of surface phases on ordered Au110 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, Au110 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.
- Inorganic Chemistry
- Physical Chemistry
- Electricity and Magnetism
- Atomic and Molecular Physics and Spectroscopy