Electrochemical surface reactions

Strehblow HH, Bettini M (1980) Electrochemical surface reactions on PbTe. J Electrochem Soc127 847-855... 

Iron and Stainless Steel. The purpose of XPS investigations on typical corrosion systems like iron or stainless steel, is the determination of the composition of the passive surface layer, if possible, as a function of depth. As a consequence of the technical and economic relevance of corrosion reactions, XPS investigations on corrosion systems are numerous. With respect to the application of XPS, there is no difference between corrosion systems and any other electrochemical surface reaction like oxide formation on noble metals. Therefore, in this paragraph only a few recent typical results of such studies, using XPS, will be mentioned. For a detailed collection of XPS corrosion studies the reader is referred to references [43,104], A review of aqueous corrosion studies, using XPS, was given by McIntyre for the elements O, Cr, Mn, Fe, Co, Ni, Cu and Mo [105], The book edited by M. Froment [111] gives an impression of the research achieved on passivity of metals up to 1983. 

Corrosion—the gradual decay of materials—occurs in many ways, all involving electrochemical surface reactions. The essence of it is the electrochemical dissolution of atoms in the surface into the ion-containing film that is in contact with the corroding metal. However, such dissolution has to be accompanied by a counter-reaction and this is often the electrochemical decomposition of water to form hydrogen on the metal surface. If that occurs, the H in the form of minute protons, H, may enter the metal, diffuse about, and cause a weakening ofmetal-metal bonds and hence stress-corrosion cracking. 

Electrosorption has also been applied in electrotechnology to either catalyse or Inhibit electrochemical surface reactions. Photoreduction of water is an example of the former, corrosion inhibition of the latter. 

Since electrochemical surface reactions involve electron transfer to or from the surface, a quantum mechanical approach becomes necessary to account for electron tunneling in such processes. Quantum mechanical treatments of electron transfer and adsorption have been reviewed recently (67-77). The Gurney treatment (68, 72, 73) assumes the transfer of an electron at the Fermi level of the metal to an H3O at its ground state at the outer Helmholtz plane. The electrode potential changes the minimum vibrational energy of the bond necessary to induce tunneling. Levich (67) has... 

The major advantage of the SECM as a patterning tool lies in its ability to drive a wide range of chemical and electrochemical surface reactions. As compared with other scanning probe techniques, e.g., STM and AFM, in an SECM experiment the mechanism of the surface process is usually known and involves electrochemical and chemical processes. Moreover, the con-... 

The mechanism of oxydesulfurization of coal has been extensively investigated by Vracar et al. (1970), Friedman and Warzinski (1977), Vetter (1967), and Joshi et al. (1982). The dissolution of sulfide minerals can be interpreted as an electrochemical surface reaction similar to the corrosion of metals. Oxygen is reduced at cathodic areas, and sulfides are dissolved liberating electrons to... 

The key feature of electrochemical surface reactions is the transfer of charge across the interface between the electrode and species in the electrolyte phase. This charge may be in the form of electrons as, for example, with the redox couple ... 

The surface chemistry of black carbon has been reviewed comprehensively electrochemical surface reactions of carbon have been surveyed" . ... 

The kinetics of electrooxidation of adsorbed CO on Pt electrodes have been interpreted as an electrochemical surface reaction involving several intermediates such as hydrated linear CO, reduced CO, and (COOH)ad species, resulting from different interactions between either CO and H2O or CO and ions. A CO and H2O adsorbate reactant pair mechanism, participating in a simultaneous charge transfer and depro-... 

The linear shape of the voltammetric curve registered in the same conditions (Fig.6, curve 1) shows that only soluble anodic dissolution products are formed in diluted acids. The same conclusion was drawn from SEM/EDAX analysis of copper(II) sulphide surface after anodic dissolution at +600 mV (SCE) for 3 h in diluted acids (Fig.5). The results are supporting the statement that in diluted acids the concentrations of H" and Cl ions and the redox potential of Cu2+/CuClJ-" pair are too small to disturb the fast and reversible electrochemical surface reaction ... 

Equation (2.22) or Eqn (2.23) is one of the most important equations in dealing with electrochemical surface reactions, which is called the Bulter—Volmer equation. 

The aim of this book is to review recent advances in the understanding of corrosion and protection mechanisms. A detailed view is provided of the chemical and electrochemical surface reactions that govern corrosion, and of the link between microscopic forces and macroscopic behavior, is provided. 

Before discussing the energy diagrams for electrochemical surface reactions, we introduce a very useful concept from electrochemistry, the normal hydrogen electrode (NHE) and the related RHE. The convention is to use the equilibrium between protons and electrons at a given potential with gas-phase to define a reference potential so that at f/=0 V with respect to the NHE, the following reaction is in equiUbrium at standard conditions (p= bar, 7 =298.15 K, pH=0) ... 

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