DC polarography: effects of electrode sphericity on the catalytic currents with non-Nernstian behavior

Gálvez, Jesús; Molina, Á.; Serna, Carmen; Saura, R.

doi:10.1016/0022-0728(86)87040-1

Cited by 8 publications

(2 citation statements)

References 13 publications

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“…As far as analysis of the derivatives concerned, most of the work have dealt with only the linear diffusion (on a planar electrode) or semi-infinite liner diffusion (on DME, or SMDE), not with spherical diffusion (on a spherical electrode), even though there are many studies on the original currents (not derivatives) with spherical electrodes from earlier days of polarographic/voltammetric works as given in general monographs [30,38,43,44] as well as in articles on particular systems and methods [45][46][47][48][49][50][51][52][53][54][55]. These include studies on EC mechanisms [45,46], CE mechanisms [46,47,54], on various pulse polarographic methods [48,55], on DC polarography [49], on AC polarography [72], on cyclic voltammetry [51], on catalytic EC mechanism with the square-wave voltammetry [52], on a double potential method [53] and on DPV at spherical and microelectrodes [56].…”

Section: Symmetry Parametersmentioning

confidence: 99%

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Advances in Derivative Voltammetry - A Search for Diagnostic Criteria of Several Electrochemical Reaction Mechanisms

Kim¹

2021

Analytical Chemistry - Advancement, Perspectives and Applications

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New methods for analysis of current-potential curves in terms of their derivatives are presented for studying various types of electrode processes – such as simple electron transfer reactions (reversible, quasi-reversible, and irreversible electron transfer) as well as chemically coupled electron transfer reactions along with a diagnostic scheme for differentiating these various types of electrochemical reaction mechanisms. Expressions for first- and higher order derivatives are derived from theoretical analytical solutions for currents for the different types of electrode mechanisms. The derivative curves are analyzed in terms of various parameters which characterize peak shape or peak symmetry with an emphasis on the second derivatives with well-defined anodic and cathodic peaks. Second derivatives can yield, in a simpler manner, the symmetry ratios; i.e., a ratio of anodic to cathodic peak-currents (ipa/ipc), and a ratio of anodic to cathodic peak-widths (Wpa/wpc) and a ratio of anodic to cathodic peak potential differences (ΔEpa/ΔEpc) or a peak separation (Epa-Epc) are evaluated, and these ratio can be related to kinetic parameters associated with a particular types of electrode mechanisms. Peaks are found to be symmetrical for a simple reversible electron transfer process (Er). However, peaks become asymmetrical when the electron transfer become slower (namely, irreversible, Eirr) or e− transfer reaction is coupled with homogeneous chemical reactions such as a prior reaction (CEr) or a follower-up reaction (ECr). From measured values of such symmetry ratios above, one can gain insight to the nature of the electrochemical systems enabling us to determine various kinetic parameters associated with a system. A diagnostic criteria for assigning an electrode mechanism is devised based on the values of asymmetry parameters measured, which are unity for a simple reversible electron transfer process.

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Section: Symmetry Parametersmentioning

confidence: 99%

“…The plots of the original currents and three derivatives were calculated according to the Eq. ( 47), ( 48), (49), and (50). As it can be expected the entire i-E curve moves upward with the diffusion-controlled current as k f increases.…”

Section: Theoretical Expressions For and The Derivativesmentioning

confidence: 99%

Advances in Derivative Voltammetry - A Search for Diagnostic Criteria of Several Electrochemical Reaction Mechanisms

Kim¹

2021

Analytical Chemistry - Advancement, Perspectives and Applications

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Electrocatalysis‐Based Kinetics Determinations

Bănică

Ion

2000

Encyclopedia of Analytical Chemistry

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The term “electrocatalysis” denotes the catalysis of an electrochemical reaction. In accord with the general definition of catalysis1 the effect of an electrocatalyst is to increase the rate of an electrochemical reaction without modifying the overall standard Gibbs energy change in the reaction. Taking the view of Faraday's law, the rate of an electrochemical reaction is expressed by the electrolytic current. Consequently, an increase in the electrolytic current is the main result of electrocatalysis. The benefits of electrocatalysis include making possible the quantitation of the catalyst itself or of some substrate compounds that are not electrochemically active or are not generally amenable to direct electrochemical determination. An appreciable improvement in selectivity may be brought about by electrocatalysis. Additionally, appropriate engineering of catalytic layers on electrode surfaces has led to the preparation of a huge variety of chemical and biochemical sensors. However, close control of the experimental conditions (temperature, electrolyte composition) is often required when dealing with electrocatalytic processes. Usually, such requirements do not give rise to any particular difficulties.

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