Sensitivity of Electrochemical Adlayer Structure to the Metal Crystallographic Orientation: Potential-Dependent Iodide Adsorption on Au(100) in Comparison with Other Low-Index Surfaces

摘要: Abstract : The potential-dependent ordered atomic structures formed for iodide adsorption on Au(100) from dilute aqueous alkali electrolytes as discerned by means of in-situ scanning tunneling microscopy (STM) are reported and compared to the corresponding behavior other two low-index faces, Au(111) (110) . As in related studies, emphasis is placed linking microscopic structural information voltammetric macroscopic electrochemical response, including use 'potentiodynamic' STM tactics where real-space images acquired during appropriate electrode potential steps or sweeps. While relatively low coverages, theta sub I approx. 0.1, sufficient lift hexagonal reconstruction, yielding large (1 x 1) domains ca-0.6 V vs SCE, adlayers only above -0.2 V. A compressible incommensurate (2 sq rt 2 p 2) phase (theta I, 0.46 - 0.49) observed between ca 0 V, which reverts a distinct 2)R45 deg structure 0. 5) featuring uniform binding twofold bridging sites. Interestingly, while latter retained locally at higher potentials, it interspersed with narrow (3-4 atom wide) strips having rotated pattern. becomes increasingly dense, eventually dominant, towards potentials. This microscopically nonuniform (or spatially modulated ) noteworthy well unusual; iodine phases display, common, uniformity given potential.