Single-crystal electrochemistry

As on previous occasions, the reader is reminded that no very extensive coverage of the literature is possible in a textbook such as this one and that the emphasis is primarily on principles and their illustration. Several monographs are available for more detailed information (see General References). Useful reviews are on future directions and anunonia synthesis [2], surface analysis [3], surface mechanisms [4], dynamics of surface reactions [5], single-crystal versus actual catalysts [6], oscillatory kinetics [7], fractals [8], surface electrochemistry [9], particle size effects [10], and supported metals [11, 12]. 

One of the main uses of these wet cells is to investigate surface electrochemistry [94, 95]. In these experiments, a single-crystal surface is prepared by UFIV teclmiqiies and then transferred into an electrochemical cell. An electrochemical reaction is then run and characterized using cyclic voltaimnetry, with the sample itself being one of the electrodes. In order to be sure that the electrochemical measurements all involved the same crystal face, for some experiments a single-crystal cube was actually oriented and polished on all six sides Following surface modification by electrochemistry, the sample is returned to UFIV for... 

Of these, the most extensive use is to identify adsorbed molecules and molecular intermediates on metal single-crystal surfaces. On these well-defined surfaces, a wealth of information can be gained about adlayers, including the nature of the surface chemical bond, molecular structural determination and geometrical orientation, evidence for surface-site specificity, and lateral (adsorbate-adsorbate) interactions. Adsorption and reaction processes in model studies relevant to heterogeneous catalysis, materials science, electrochemistry, and microelectronics device failure and fabrication have been studied by this technique. 

The surface electrochemistry of Pt single-crystal electrodes has been exhaustively studied using cyclic voltammetry.100 186 188 197 209 412 753-756,771,-773,779-788,794-796 qq g technique has been proved to be highly... 

While contrasting results obtained by different experimental techniques as well as different theoretical methods are not surprising, internal controversies over AX values in electrochemistry are more serious. The controversy referred to here32 is that about the sequence of metal-water interactions for the different faces of fee metals. More recently, a controversy has also arisen about single-crystal faces of Cd. 

Numerous works have been implemented on tellurium electrochemistry and its adsorption at metal surfaces. The morphological structures of electrodeposited Te layers at various stages of deposition (first UPD, second UPD, and bulk deposition) are now well known [88-93]. As discussed in the previous paragraphs, Stickney and co-workers have carried out detailed characterizations of the first Te monolayer on Au single-crystal surfaces in order to establish the method of electrochemical atomic layer epitaxy of CdTe. 

S.2.3.2 Single-Crystal Photoelectrodes - A Closer Look into Interfacial Electrochemistry... 

The electrochemistry of single-crystal and polycrystalline pyrite electrodes in acidic and alkaline aqueous solutions has been investigated extensively. Emphasis has been laid on the complex anodic oxidation process of pyrite and its products, which appears to proceed via an autocatalytic pathway [160]. A number of investigations and reviews have been published on this subject [161]. Electrochemical corrosion has been observed in the dark on single crystals and, more drastically, on polycrystalline pyrite [162]. Overall, the electrochemical path for the corrosion of n-EeS2 pyrite in water under illumination has been described as a 15 h" reaction ... 

Soriaga, M. P., D. A. Harrington, J. L. Stickney, and A. Wiekowski, Ultrahigh-vacuum surface analytical methods in electrochemical studies of single-crystal surfaces, in Modem Aspects of Electrochemistry, J. O M. Bockris et al., Eds., Vol. 28, Kluwer, New York, 1996, p. 1. 

Markovic NM, Grgur BN, Ross PN. 1997. Temperature-dependent hydrogen electrochemistry on platinum low-index single-crystal surfaces in acid solutions. J Phys Chem B 101 5405-5413. 

Bhzanac BB, Arenz M, Ross PN, Markovic NM. 2004b. Surface electrochemistry of CO on reconstructed gold single crystal surfaces studied by infrared reflection absorption spectroscopy and rotating disk electrode. J Am Chem Soc 126 10130-10141. 

Palaikis L, Zurawski D, Hourani M, Wieckowski A. 1988. Surface electrochemistry of carbon monoxide adsorbed from electrolytic solutions at single crystal surfaces of Pt(lll) and Pt(lOO). Surf Sci 199 183-198. 

Climent V, Gomez R, Orts JM, Aldaz A, Eehu JM. 2000. Potential of zero total charge of platinum single crystal electrodes. In Jerkiewicz G, Eehu JM, Popov BN, eds. The Electrochemistry Society Proceedings (Hydrogen at Surface and Interfaces). Pennington, NJ The Electrochemical Society, pp. 12-30. 

Figures 12.1 and 12.2 show that the spectroelectrochemical cell is basically a thin-layer electrochemistry cell (TLE) with a solution gap of 25 pm [Hubbard, 1973]. The metal working electrode may be polycrystalline or a single crystal. Emptying the gap out of the adsorbate molecules due to molecules oxidation, and refilling via molecular...

Mono- or single-crystal materials are undoubtedly the most straightforward to handle conceptually, however, and we start our consideration of electrochemistry by examining some simple substances to show how the surface structure follows immediately from the bulk structure we will need this information in chapter 2, since modern single-crystal studies have shed considerable light on the mechanism of many prototypical electrochemical reactions. The great majority of electrode materials are either elemental metals or metal alloys, most of which have a face-centred or body-centred cubic structure, or one based on a hexagonal close-packed array of atoms. 

This j taper describes equipment, procedures and results for investigation of transition metal surface reactivity. Specifically, the surface reactivity of copper single crystals was examined under conditions relevant to the electrochemistry and corrosion of copper. 

The authors acknowledge very helpful discussions with Dr. R. Adzic of the Institute of Electrochemistry, Belgrade, concerning the underpotential deposition of lead on single crystal silver substrates after chemical polishing. The authors also acknowledge support of the research by the U.S. Office of Naval Research. 

We have recently modified U7) one of the several radiochemical methods (U5) which have been used for surface electrochemistry investigations in order to characterize adsorption on well-defined, single crystal electrodes. Below, we will describe the technique and identify some challenging issues which we will be able to address. The proposed method is sensitive to a few percent of a monolayer at smooth surfaces, is nondestructive and simple to use. The radiochemical measurements can be made with all compounds which can be labelled with reasonably long-lived, preferably g- emitting radioisotopes. We believe this technique will fulfill the quantitative function in in situ surface analysis as Auger spectroscopy currently does in vacuum, ex situ characterization of electrodes. 

A voltammetric characterization of platinum single crystal surfaces produced by these three methods shows that a very similar surface order and cleanliness are obtained in each case. The features embodied by the third method which we use for the radio-electrochemistry work, are as follows ... 

Silicon has been and will most probably continue to be the dominant material in semiconductor technology. Although the defect-free silicon single crystal is one of the best understood systems in materials science, its electrochemistry to many people is still a matter of alchemy. This view is partly a result of the interdisciplinary aspects of the topic Physics meets chemistry at the silicon-electrolyte interface. 

The problem with all three of the above scenarios is that they require an understanding of the surface chemistry of compound semiconductor in aqueous solutions. Much more is known about the surface chemistry and reactivity of Au in aqueous solutions. A prerequisite, then, to the use of a compound semiconductor as a substrate for compound electrodeposition is to gain a better understanding of the substrate s reactivity under electro-chemically relevant conditions. Our initial studies of compound reactivity in electrochemical environments involved CdTe single crystals [391]. The electrochemistry of CdTe is reasonably well understood from electrodeposition studies (Table 1), and single crystals are commercially available. 

Since the number of papers dealing with the electrochemistry of Pt single crystals exceeds several hundreds, only some of them, published in the last few years could be referred to [179,186-205]. 

A chapter on the electrochemistry of gold was published in the 4th volume of Encyclopedia of Electrochemistry of the Elements in 1975. At that time, mostly polycrystalline gold (pc-Au) electrodes were used, although already in the early sixties, the studies involving single-crystal electrodes had also been published. It appears from a review of the recent literature that polycrystalline gold electrodes are still in use however, the following trends are emphasized the most ... 

The chapter on the electrochemistry of silver was published in 1978 as a part of the 8th volume of Encyclopedia of Electrochemistry of the Elements. At that time, most of the electrochemical properties of silver were limited to polycrystalline Ag (pc-Ag) surfaces, although the first studies with single-crystal electrodes were already described. Since the time that this chapter was published, one can indicate three main trends ... 

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