Kinetics of Electrochemical Reactions

Reactant concentrations Cyj in the bulk solution, as well as the Galvani potential between the electrode and the bulk solution (which is a constituent term in electrode potential E), appear in kinetic equations such as (6.8). However, the reacting particles are not those in the bulk solution but those close to the electrode surface, near the outer Helmholtz plane when there is no specific adsorption, and near the inner Helmholtz plane when there is specific adsorption. Both the particle concentrations and the potential differ between these regions and the bulk solution. It was first pointed out by Afexander N. Frumkin in 1933 that for this reason, the kinetics of electrochemical reactions should strongly depend on EDL structure at the electrode surface. 

When considering how the adsorption of different snbstances on electrodes inflnences the kinetics of electrochemical reactions, we mnst distingnish two cases that where components are adsorbed which are involved in the reaction, and that where incidental snbstances are adsorbed which are not involved in the reaction. 

Zhdanov VP, Kasemo B. 2002. Kinetics of electrochemical reactions from single crystals to nm-sized supported particles. Surf Sci 521 L655-L661. 

Oxide compounds are widely used as cathodic materials in the power sources and electrochemical generators. Some literature data indicates that cathodic materials based on nonstoichiometric oxide compounds make it possible to increase the solid-phase reduction process. The kinetics of electrochemical reactions and consequently the current density are the higher, the greater the degree of deviation from stoichiometry, and the lager the number of the defects in the compounds structure [1,2]. 

Let us note in conclusion that the thermodynamic approach has widely been used to describe the kinetics of electrochemical reactions at an illuminated semiconductor electrode (see, for example, Gerischer, 1977c Dog-onadze and Kuznetsov, 1975). Clearness and simplicity are an unqualified advantage of this approach, but the use of the quasilevel concept is not justified in all the cases. In particular, conditions (48) alone appear to be insufficient to substantiate the applicability of the quasilevel concept to the description of the processes of electron transfer across the interface (for greater details, see Pleskov and Gurevich, 1983 Nozik, 1978). Obviously, if photogeneration of the carriers occurs mainly near the surface, at which a... 

The condition of the platinum electrode surface can play an important role in the kinetics of electrochemical reactions, but for the kinetics of dithionite oxidation it was found that the platinum surface condition did not seriously interfere (see section 6.3). 

Impedance spectroscopy is predestined to separate the contributions of bulk and electrodes to the overall electrical properties of a solid and can thus be employed to investigate the kinetics of electrochemical reactions. However, the relaxation fre-... 

Refs. [i] Erdey-Gruz T, Volmer M (1930) Z Phys Chem A150 203 [ii] Parsons R (1974) Pure Appl Chem 37 503 [in] Inzelt G (2002) Kinetics of electrochemical reactions. In Scholz F (ed) Electroanalytical methods. Springer, Berlin, pp 29-33 [iv] BardAJ Faulkner LR (2001) Electrochemical methods. 2nd edn. Wiley, New York, pp 98-103... 

Refs. [i] Erdey-Gruz T, Volmer M (1930) Z phys Chem A150 203 [ii] Bard AJ, Faulkner LR (2001) Electrochemical methods. 2nd edn. Wiley, New York, pp 87-135 [iii] Inzelt G (2002) Kinetics of electrochemical reactions. In Scholz F (ed) Electroanalytical methods. Springer, Berlin, pp 29-49 [iv] Brett CMA, Oliveira Brett AM (1993) Electrochemistry. Oxford University Press, Orford, pp 70-81, 104-105 [v] Bockris JO M, Razumney GA (1967) Electrocrystallization. Plenum, New York, p 11 [vi] Bockris JO M, Reddy AKN (1970) Modern electrochemistry. Plenum, New York [vii] Bockris JO M, Rand DAJ, Welch BJ (1977) Trends in electrochemistry. Plenum, New York, p 10 [viii] Bockris JO M, Khan SUM (1993) Surface electrochemistry. Plenum, New York, pp 213-215 ... 

Refs. [i] Cohen ER, Cvitas T, Frey JG, et al. (eds) (2007) IUPAC quantities, units and symbols in physical chemistry, 3rd edn. RSCPublish-ing Cambridge, p 73 [ii] Komorsky-Lovric S (2002) Working electrodes. In Scholz F (ed) Electroanalytical methods. Springer, Berlin, pp 287-290 [iii] Inzelt G (2002) Kinetics of electrochemical reactions. In Scholz F (ed) Electroanalytical methods. Springer, Berlin, pp 245-278 [iv] Petrii OA, Tsirlina GA (2002) Electrode potentials. In Bard AJ, Stratman M, Gileadi E, Urbakh M (eds) Thermodynamics and electrified interfaces. Encyclopedia of electrochemistry, vol. 1. Wiley-VCH, Weinheim, pp 1-23 [v] Parsons R (1974) Pure Appl Chem 37 503 [vi] Trasatti S, Parsons R (1986) Pure Appl Chem 58 437... 

Studies in nonaqueous dipolar aprotic solvents allowed the elucidation of the complicated role of the solvent nature in determining the - double layer structure and kinetics of electrochemical reactions. Special attention was paid to the phenomenon of ion - solvation and its effect on -> standard electrode potentials. Experimental studies of the various electrochemical systems in nonaqueous media greatly contributed to the advancement of the theory of elemental electron-transfer reactions across charged interfaces via the so-called energy of solvent reorganization. 

With continuing increase in anode potential, the current-potential relationship deviates from the linear relationship. As the potential continues to increase, the increase in the current slows down until it reaches a maximum and then decreases to a minimum point, and finally increases to the limiting current plateau. This is a transition from kinetics of electrochemical reaction domain to mass transport domain. This region may have a very different shape depending on electrolytes, potential scan rate, and other factors. Details of this region are discussed elsewhere [7,8]. 

L. I. Krishtalik, Kinetics of electrochemical reactions at metal-solution interfaces, in Comprehensive Treatise of Electrochemistry. Vol. 7, B. E. Conway, J. O M. Bockris, E. Yeager, S, U. M. Khan and R. E. White, editors. Plenum Press, New York, 1983, pp. 87-172. 

The examples snmmarized in the chapter were chosen to demonstrate the emergence of in sitn electrochemical snrface science and its parallels with traditional UHV-based snrface science. Even though we emphasize a strong link between metal surface phenomena in vacuum and electrochemical environments, there are substantial differences between these two environments the presence of spectator species from snpporting electrolyte on electrodes, even in the absence of the fuel, sets the electrochemical interface apart from the same interface in UHV environments. This phenomenon drives the kinetics of electrochemical reactions by controlling the number of active sites. Our examples reveal the surface science of electrocatalysis on bimetallic surfaces is still in its infancy, but we can recognize electrocatalytic trends that form the basis for the predictive ability to tailor active sites with desirable reactivity. 

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