Some consequences of potential-induced surface reconstruction upon the double-layer structure and electrocatalytic properties of Au(100) in aqueous perchloric acid were explored by means of cyclic voltammetry and differential capacitance measurements, together with in situ scanning tunnelling microscopy. Initially unreconstructed (1 x 1) Au(100) yielded capacitance-potential profiles in dilute (1mM) perchloric acid in the vicinity of the potential of zero charge Epzc which were consistent with the presence of an essentially uniform distribution of electronic charge across the surface. Upon electrochemically inducing hexagonal surface reconstruction by holding the potential below −0.2V for periods of up to ca. 20min, these capacitance-potential minima were substantially broadened. The latter observation implicated the presence of electrostatically distinct surface domains with “local” Epzc values that were significantly (0.1 to 0.2V) lower as well as higher than that for unreconstructed Au(100), having dimensions at least comparable with the Debye length of the diffuse layer (ca. 9.5mn) in 1mM HClO4. This finding was consistent with the real-space surface morphology as obtained by in situ scanning tunnelling microscopy under these conditions, which showed the common presence of corrugated features, such as edges of reconstructed strands, in addition to domains featuring quasi-hexagonal atomic packing. The sharp potential-induced removal of the reconstruction inferred from the appearance of a voltammetric feature at 0.6VSCE in perchloric acid was confirmed by scanning tunnelling microscopy data acquired during potential sweeps, which also show that the 24% excess gold atoms released form arrays of metal clusters. The rates of proton electroreduction were significantly (1.3 to 1.7-fold) accelerated by Au(100) reconstruction. These effects appear to be due to the involvement of gold atomic sites featuring lower coordination numbers which were seen to be formed upon surface reconstruction.

Some Electrochemical Consequences of Potential-Induced Surface Reconstruction on Au(100) - Double-Layer Non-Uniformity and Electrode Kinetics. A.Hamelin, L.Stoicoviciu, G.J.Edens, X.Gao, M.J.Weaver: Journal of Electroanalytical Chemistry, 1994, 365[1-2], 47-57