Eine Einführung in die Methoden zur Untersuchung der Kinetik von Elektrodenprozessen

Gerischer, H.

doi:10.1002/bbpc.19550590706

Cited by 23 publications

(3 citation statements)

References 48 publications

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“…The signs of all other current quantities and derived functions, such as that of the externally applied current, are fixed by this procedure. k,,c = v,,c e RT e RT [6] for anodic and cathodic charge transfer steps, respectively. Here, A~,a* and A~,,~* are the changes in the chemical potential of the system required for the formation of one mole of activated complex from reactants for anodic and cathodic steps, respectively.…”

Section: Definitions and Fundamental Relationsmentioning

confidence: 99%

“…From Eqs. [1], [3], [5], and [6], the current applied to a polyelectrode system in a steady state is given by: e aT --k.,.~,~Ir (C,P'~) r e RT e RT dS [7] Equation [7] is the fundamental expression of the present model of two-phase polyelectrode systems; it includes all the charge transfer steps occurring at an electrode-solution interphase, whether rate-determining or not. Since A4'-of Eq.…”

Section: Definitions and Fundamental Relationsmentioning

confidence: 99%

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Kinetic Studies on Corrosion Systems

Posey¹

1959

J. Electrochem. Soc.

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Electrochemical kinetics has been applied to the case of corroding polyelectrodes under activation control for the situation where the rates of partial processes vary over the surface of an electrode. Explicit expressions have been derived for rate and potential in the simplest polyelectrode systems. The kinetics of galvanic couples under activation control has been derived with emphasis on the significance of measurable quantities. The use of steady-state polarizability measurements, potentiostatic measurements, and galvanostatic measurements in the study of polyelectrode systems has been outlined.Numerous investigators have contributed to the foundations ~ and experimental applications of electrochemical kinetics and comprehensive reviews of this work have been published (4-6). Much of the existing theory treats the case of a single over-all reaction under activation controF at an electrodesolution interphase [e.g., a metal-metal ion equilibrium, or a redox reaction at an inert electrode (8)], and one of the most general treatments of such a system' has been presented by Parsons (9). Wagner and Traud (10), Kimball (11), and Audubert (12) have been among the few to examine corrosion systems from a systematic kinetic viewpoint. However, in the study of some of the more complex electrochemical situations, such as those occurring in many corrosion systems, there appears to be a need for a more extensive treatment suitable for interpreting the phenomenology. In the present report, an elementary electrochemical kinetic treatment of twophase polyelectrode systems ~ and galvanic couples under activation control has been developed, and the application of the theory to the analysis of corroding polyelectrodcs has been outlined for several types of steady-state measurements. The results of an experimental investigation on a particular polyelectrode system will be presented in a subsequent report.' Operated by Union Carbide Corporation for the U. S. Atomic Energy Commission.-9 The source equations of electrochemical kinetics may be found in the works of Butler (1), Bowden and Rideal (2), and Erdey-Gruz and Volmer (3). ~Use of the term, activation control, here corresponds to the sense of the designation, "Durchtrittstiberspannung," as employed by Vetter (7) to distinguish between cases where the charge transfer step in an electrochemical reaction or partial process is ratedetermining and those where the higher activation energy of a precursor step or a subsequent step in the reaction determines the rate.' The designation, system, is used-here to refer to an electrode plus its liquid environment.~The term, polyelectrode, as used here, refers to the situation where more than one chemicalIy distinct individual or partial process is occurring at the same electrode-solution interphase. The term, two-phase polyelcctrode system, denotes a metallic polyeleetrode in contact with a nonmetallic environment in the liquid state. The case of intervention of a third phase (e.g., an oxide film) between metal and solution is not considered...

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Section: Definitions and Fundamental Relationsmentioning

confidence: 99%

Section: Definitions and Fundamental Relationsmentioning

confidence: 99%

Kinetic Studies on Corrosion Systems

Posey¹

1959

J. Electrochem. Soc.

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“…Galvanostatic measurements.--Details of galvanostatic or constant current pulse measurements can be found elsewhere (13)(14). The glass cell used was similar to one described previously (1) except that measurements were made with the amalgam drop hanging directly from the capillary and the current was conducted through the capillary to the drop.…”

Section: Methodsmentioning

confidence: 99%

The Zn[sup 2+]∕Zn(Hg) Electrode Reaction in Binary Mixtures of Water and n-Propanol

Miles¹,

Gerischer

1971

J. Electrochem. Soc.

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The kinetics of the Z n 2 + / Z n ( H g ) electrode reaction were investigated in binary mixtures of water and n-propanol. The apparent cathodic transfer coefficient increases from 0.25 in water to 0.39 in 0.04 mole fraction n-propanol, then gradually decreases to a value of about 0.3 as further alcohol is added. The apparent exchange current decreases sharply from 18 m A / c m ~ in water to about 1 m A / c m 2 in 0.04 mole fraction n-propanol, then gradually increases as the concentration of n -p r o p a n o l increases. Above 0.9 mole fraction alcohol, the apparent exchange current rapidly increases as the water concentration falls below the concentration of the excess LiC104 electrolyte. These variations are interpreted in terms of specific adsorption of n-propanol on the electrode surface and preferential solvation of the Zn + + ions in solution by water molecules and by a change to a reaction mechanism involving ZnC104 + as water molecules become unavailable for the preferential solvation.Many investigations of the Z n 2 + / Z n ( H g ) electrode reaction in aqueous solutions have been made (1-6). Although the existence of Zn + as an intermediate in the reaction mechanism has been proposed (6-9), it is generally accepted that the charge-transfer reaction kinetics can be best described with a single two-electron step (10-12). Zn 2+ .aq -t-2 e -~ Zn[1]Since solvation and desolvation processes represent the main energy barriers in such electrode reactions, it is of interest to investigate the effect of the solvent on this reaction. The p r i m a r y purpose of this study is to investigate the behavior of the apparent anodic and cathodic transfer coefficients and the apparent exchange current for the Z n 2 + / Z n ( H g ) electrode reaction in b i n a r y mixtures of water and n-propanol. ExperimentalSolutions and chemicals.--Bi-distilled water and chromatography grade n-propanol were used in preparing the b i n a r y solvent. The electrolyte concentrations were always 0.0083M Zn(CIO4)2-6H20, 1.0M LiC104, and 0.02M HC104. The water content of these solutions was determined by Karl Fischer titrations. Bubbling purified nitrogen through the solutions removed dissolved oxygen. The zinc concentration in the amalgam was maintained at about 0.7M (0.01 mole fraction zinc). * E l e c t r o c h e m i c a l S o c i e t y A c t i v e M e m b e r . ** Electrochemical Society A c t i v e M e m b e r through Deutsche Bunsen-Gesellschaft.I P r e s e n t address: Fritz-Haber-Institut dcr M a x -P l a n c k -G e s e l lschaft, West Berlin, G e r m a n y .

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Unsere Vorstellungen über die Kinetik von Elektrodenprozessen

Vetter

1955

Zeitschrift für Elektrochemie, Berichte der Bunsengesellschaft

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In der Elektrodenkinetik entspricht die Stromdichte i der Reaktionsgeschwindigkeit, die bei festem Potential von den Konzentrationen ci mit einer Reaktionsordnung z0,i, zr,i usw. abhängt. Die Änderung des Potentials entspricht bei der Durchtrittsüberspannung einer Änderung der Aktivierungsenergie mit einem Durchtrittsfaktor 0 < α < 1. Die Durchtrittsüberspannung ηD hängt nur von der Austauschstromdichte i0 und dem Durchtrittsfaktor α ab. Unmittelbar maßgebend für die Größe des Potentials oder der Überspannung η = ϵ ‐ ϵ0 sind die Vorgänge in der Durchtrittsreaktion. Andere Vorgänge wirken nur mittelbar durch Veränderungen in der Durchtrittsreaktion ein.Die Potentialeinstellung erfolgt sowohl bei den Redoxelektroden (Elektronendurchtritt durch die Doppelschicht) wie bei den Metallionenelektroden (Metallionendurchtritt) durch zwei entgegengesetzte potentialabhängige anodische und kathodische Teilstromdichten i+ > 0 und i‐ < 0. Einige aufgeklärte Mechanismen werden als Beispiel für verschiedene Elektrodenarten angegeben.Die Gesamtüberspannung wird in Durchtritts‐, Diffusions‐ und Reaktionsüberspannung aufgeteilt und es werden hierfür weitere Beispiele mit Reaktionsgrenzströmen gegeben. Ihre Beziehung zu älteren Überspannungsarten wird diskutiert. Die Kristallisationsüberspannung wird als Reaktionsüberspannungsart gedeutet. Der Volmersche Mechanismus führt zu reiner Durchtrittsüberspannung und der Tafelsche Mechanismus der Wasserstoffüberspannung zu reiner Reaktionsüberspannung.

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Eine Einführung in die Methoden zur Untersuchung der Kinetik von Elektrodenprozessen

Cited by 23 publications

References 48 publications

Kinetic Studies on Corrosion Systems

Kinetic Studies on Corrosion Systems

The Zn[sup 2+]∕Zn(Hg) Electrode Reaction in Binary Mixtures of Water and n-Propanol

Unsere Vorstellungen über die Kinetik von Elektrodenprozessen

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