Electrochemical Classification

From an electrochemical point of view, proteins can be classified as follows  

Prior to electron exchange, strong adsorption of mostly globular molecules takes place which raises the question what happens to secondary and tertiary structures in the vicinity of the electrode On the one hand, there is evidence for unfolding, flattening, and even splitting of globuli and, on the other hand, some enzymes are still active in the adsorbed state. 

Frequently, proteins are classified according to the results of the Koryta equation  

In view of the well-known amphoteric character of proteins,the reactivity for electron transfer is clearly dependent on the environment, particularly on pH and ionic strength. For instance, in the case of horse heart cytochrome c, the transition from the neutral to the alkaline state involves replacement of the sixth ligand of the heme iron, methionine-80, by lysine-79 and therefore the reduction takes place more reversibly.  

The interaction of ions with a protein of N identical binding sites is described by the site-binding mode/ for the ligand L. The probability (r) that a given site is occupied by L, which has an activity aL, is 

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THE BASIC ELECTROCHEMICAL concepts and ideas underlying, the phenomena of metal dissolution are reviewed. The emphasis is on the electrochemistry of metallic corrosion in aqueous solutions. Hie role of oxidation potentials as a measure of the "driving force" is discussed and the energetic factors which determine the relative electrode potential are described. It is shown that a consideration of electrochemical kinetics, in terms of current-voltage characteristics, allows an electrochemical classification of metals and leads to the modern views of the electrochemical mechanism of corrosion and passivity. 

A general electrochemical classification of reaction type is as follows ... 

Any fundamental classification of corrosion control must be based on the electrochemical mechanism of corrosion, and Evans diagrams may be constructed (Fig. 1.27, Section 1.4) illustrating... 

FIGURE 4-27 Classification of composite electrodes used in controlled-potential electrochemical techniques. (Reproduced with permission from reference 87.)... 

A complete classification of electrochemical promotion (EP) studies on the basis of the type of solid electrolyte used is given in Table 4.1 of Chapter 4 together with the corresponding references. These studies are further discussed in detail in Chapters 8 to 10. 

Table 4.1 lists all published electrochemical promotion studies of 58 catalytic reactions on the basis of the type of electrolyte used. Each of these reactions is discussed in Chapters 8 to 10 which follow the same reaction classification scheme. 

Table 4.1. Electrochemical promotion studies classification based on the type of solid electrolyte...

Table 4.2. Classification of electrochemical promotion studies on the basis of catalytic reaction.

Table 4.3. Classification of Electrochemical Promotion studies on the basis of catalytic reaction, showing the observed kinetic order with respect to the electron donor (D) and electron acceptor (A) reactant and the corresponding global rvs

C.G. Vayenas, S. Brosda, and C. Pliangos, Rules and Mathematical Modeling of Electrochemical and Chemical Promotion 1. Reaction Classification and Promotional Rules,/. Catal., in press (2001). 

Table 6.1. Classification of Electrochemical Promotion studies on the basis of global r vs.

Crystalline solids are built up of regular arrangements of atoms in three dimensions these arrangements can be represented by a repeat unit or motif called a unit cell. A unit cell is defined as the smallest repeating unit that shows the fuU symmetry of the crystal structure. A perfect crystal may be defined as one in which all the atoms are at rest on their correct lattice positions in the crystal structure. Such a perfect crystal can be obtained, hypothetically, only at absolute zero. At all real temperatures, crystalline solids generally depart from perfect order and contain several types of defects, which are responsible for many important solid-state phenomena, such as diffusion, electrical conduction, electrochemical reactions, and so on. Various schemes have been proposed for the classification of defects. Here the size and shape of the defect are used as a basis for classification. 

M. T. M. (1999) Mechanistic classification of electrochemical oscillators - operational experimental strategy./. Electroanal. Chem, 478, 50-66. 

Figure 2.1 Classification of electrochemical electron transfer reaction on metal electrodes. (See color insert.)...

The classification of electrodes is based upon the chemical nature of the substances participating in the electrochemical process [75]. Electrodes of the first type are systems in which the reduced forms are metals of electrodes and oxidized forms are ions of the same metal. Electrodes of second type are systems in which the metal is covered by a layer of low soluble salts (or oxide), and the solution contains anions of these salts (for oxide-OH ions). The Nernst equation for electrodes of the second type can be written as ... 

Thevenot D.R., Toth K., Durst R.A., Wilson G.S., Electrochemical biosensors Recommended definitions and classification, Pure Appl. Chem. 1999 71 2333-2348. 

Electrochemical Adsorption at Catalytic Electrodes. A classification of adsorption processes at catalytic electrodes, such as platinum or rhodium, first proposed by Horanyi (24) and further developed by Wieckowski (21,25,26), categorizes adsorption processes into three fundamental groups ... 

The discussion and classification of reagents is masterful in identifying Ingold s new nomenclature and principles with more widely known oxidation-reduction and acid-base theory. The 1953 lectures at Cornell University, published as Structure and Mechanism in Organic Chemistry, follow this same strategy, showing how old classification schemes overlap with each other and how apparent inconsistencies disappear as old schemes are incorporated into the new one. Nineteenth-century Berzelian electrochemical dualism, revived by Lapworth and Robinson in the cationic/anionic schema, disappears into the electrophilic/nucleophilic language. 

Scheme 3 Classification of electrochemical functional group interconversions (FGI s).

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