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The underpotential deposition of Cu onto Au(111) in different electrolytes has been investigated by LEED, RHEED and AES. Ordered layers of (√3 × √3) R30° and (2.2 × 2.2) type were found for Cu at medium coverages in sulfate and perchlorate solutions, respectively. The formation of different superstructures in different electrolytes is caused by the specific adsorption of the anions.

The structural and morphological variations of the surfaces of polycrystalline silver foils upon heating in ultrahigh vacuum (UHV) or in reacting gases related to methanol oxidation have been investigated using scanning electron microscopy (SEM) and reflection high-energy electron diffraction (RHEED). Thermal etching under UHV conditions with and without net evaporation of silver atoms results in two distinct restructural features: the formation of surface hill-and-valley structures including low-index faces, and the preferential development of (012) facets. In the presence of an oxygen atmosphere, as well a s for conditions of methanol oxidation, a strong surface facetting occurs, depending on the composition and temperature. Flat facets, terrace-and-step structures, pits, as well as combinations thereof, may be formed, and the underlying mechanisms are qualitatively discussed on the basis of the related chemical processes and thermodynamic principles.

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