Single-Crystal Electrode Surfaces

The open structure of the Ru(ioio) surface (c.f, Fig. lb) is expected to react with H2O at very low potentials and become covered with OH species. UHV data indicate that oxygen adsorption on this surface produces c(2x4)-2O and (2xl)p2mg-2O overlayers with O atoms occupying the three-fold hep sites formed by two atoms in the first atomic layer and one atom in the second layer. These three-fold sites are the orrly likely candidates for sulfate or 

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Soriaga M P 1992 Ultra-high vacuum techniques in the study of single-crystal electrode surfaces Prog. Surf. Sc/. 39 325... 

Reaction Kinetics and Mechanism on Metal Single Crystal Electrode Surfaces AdiiC, R. 21... 

Reaction Kinetics and Mechanisms on Metal Single Crystal Electrode Surfaces Recent Developments in Faradaic Rectification Studies... 

Rhee CK, Kim D-K. 2001. Electrochemical scanning mnnehng microscope smdy of irreversibly adsorbed Te on a Pt(l 11) single crystal electrode surface. J Electroanal Chem 506 149-154. 

Lin W-F, Christensen PA, Hamnett A, Zei MS, Ertl G. 2000. The electro-oxidation of CO at the Ru(OOOl) single-crystal electrode surface. J Phys Chem B 104 6642. 

In the following section, we focus on imaging single-crystal electrode surfaces that are of relevance to electrocatalysis. We will first deal with flat, defect-free terraces as well as with more real surfaces with monoatomic high steps as the most common active sites. We will then explore various strategies for nano structuring surfaces, for example, by repetitive oxidation-reduction cycles (ORCs). 

The chemisorption of species occurs at specific sites on the electrode, for example on top of certain atoms, or in the bridge position between two atoms. Therefore, most adsorption studies are performed on well-defined surfaces, which means either on the surface of a liquid electrode or on a particular surface plane of a single crystal. Only fairly recently have electrochemists learned to prepare clean single crystal electrode surfaces, and much of the older work was done on mercury or on amalgams. 

Inspired by these Surface Science studies at the gas-solid interface, the field of electrochemical Surface Science ( Surface Electrochemistry ) has developed similar conceptual and experimental approaches to characterize electrochemical surface processes on the molecular level. Single-crystal electrode surfaces inside liquid electrolytes provide electrochemical interfaces of well-controlled structure and composition [2-9]. In addition, novel in situ surface characterization techniques, such as optical spectroscopies, X-ray scattering, and local probe imaging techniques, have become available and helped to understand electrochemical interfaces at the atomic or molecular level [10-18]. Today, Surface electrochemistry represents an important field of research that has recognized the study of chemical bonding at electrochemical interfaces as the basis for an understanding of structure-reactivity relationships and mechanistic reaction pathways. 

Second Harmonic Generation as an In-situ Probe of Single Crystal Electrode Surfaces... 

The review will begin with a brief description of the progress in the field over the past three decades and will provide a perspective of how the electrochemical measurements have developed in this growing field. This will be followed by a theoretical section which provides some general theoretical principles behind the technique. A description of some of the new microscopic approaches to modelling the nonlinear source currents from metal surfaces will also be presented. An experimental technique section will describe the details involved in making a variety of surface SH measurements. A summary of the results of experimental studies conducted in the past few years on single crystal electrode surfaces in solution will follow. The discussion will draw upon related work performed in UHV and studies on polycrystalline surfaces where comparisons are appropriate. For a more comprehensive discussion of these later two topics, the reader is referred to several other recent reviews [7,9]. 

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