Reversible Electrode Processes Research Articles

Chronopotentometric study of Cu(I)/Pt electrode processes in molten Na 2Si 2O 5

In the present paper chronopotentiometry was employed to investigate the transport process and mechanism of the Cu(I) ion reduction in liquid Na 2Si 2O 5 on platinum electrodes over the temperature range from 1283 to 1423 K. The Sand product | − j c | τ 1 2 from the region of its constancy was a linear function of concentration and the diffusion coefficients of the Cu(I) ion in Na 2Si 2O 5 were 7.88 × 10 −6 and 2.53 × 10 −5 cm 2s −1 for 1283 and 1423 K, respectively. The diffusion process of the Cu(I) ion in liquid Na 2Si 2O 5 satisfies the Arrhenius' equation. The reduction process of the Cu(I) ion at temperatures lower than the melting point of copper was defined as a reversible electrode process with insoluble products. The experimental curves for the same process occurring at temperatures exceeding the melting point of copper were described numerically by an equation allowing for diffusion of copper deposited in the reversible electrode reaction into the electrode.

Reversible electrode processes involving multistep mechanisms for cadmium dithiocarbamates and diselenocarbamates at mercury electrodes

Resultats d'etudes par voltammetrie cyclique, polarographie et polarographie a impulsions differentielles, des reactions d'oxydation et de reduction electrochimique

Differential pulse polarography in the alternating pulse mode

A polarographic two-drop pulse technique for trace analysis is described. By using a second pulse, in the opposite direction to the first one, on the second drop, a high current sensitivity is obtained, with a very flat background. The theoretical response for a reversible electrode process is presented together with experimental results for the reduction of Pb 2+ in hydrochloric acid medium. It is shown that without enrichment determination of lead at concentrations as low as 71n M is possible with this technique.

Linear sweep voltammetry at the tubular electrode

The theory of linear sweep voltammetry at the tubular electrode has been developed for reversible electrode processes. The convective diffusion differential equations have been transformed to an integral equation which is solved numerically. The theoretical current—potential curves at different velocities of the solution have been calculated. Comparison with experiments using a tubular electrode shows satisfactory agreement.

Chronopotentiometry at a tubular graphite electrode

The theory of chronopotentiomety at a tubular graphite electrode has been developed for reversible electrode processes. The convective diffusion equations for the potential-time curves have been derived and the effect of velocity of the solution flowing through the electrode on the transition time has been studied. It is observed that with an increase in velocity the transition time increases.

The theory of the ac voltammetry of reversible electrode processes at tubUlar electrodes

A theory describing the alternating current response to an ac potential superimposed on a de potential is described for reversible electrode reactions at both tubular and channel electrodes. At high frequencies the current is phase shifted through π /4 as predicted by the classical Warburg impedance expression. At lower frequencies the effect of convection causes the phase shift, to fall below π /4.

The theory of the ac voltammetry of reversible electrode processes at tubular electrodes

A theory describing the alternating current response to an ac potential superimposed on a de potential is described for reversible electrode reactions at both tubular and channel electrodes. At high frequencies the current is phase shifted through π/4 as predicted by the classical Warburg impedance expression. At lower frequencies the effect of convection causes the phase shift, to fall below π/4.

Solvent effects on redox potentials studies in N-methylformamide

The redox behaviour of LiClO 4 , NaClO 4 , KClO 4 , RbClO 4 , CsClO 4 , TiClO 4 , Ba(ClO 4 ) 2 , Cu(CF 3 SO 3 ) 2 , Cd(CF 3 SO 3 ) 2 , Zn(CF 3 SO) 2 , Zn(ClO 4 ) 2 ·2 H 2 O, (Et 4 N) 3 Fe(CN) 6 , (Bu 4 N) 3 Fe(CN) 6 , (Et 4 N) 3 Mn(CN) 6 , (Bu 4 N) 3 Mn(CN) 6 , ferrocene (biscyclopentadienyl-iron(II), bis(biphenyl)chromium tetraphenylborate and perylene has been studied in N-methylformamide employing polarography and cyclic voltammetry. Standard redox potentials have been estimated from polarographic half wave potentials—measured versus bis(biphenyl)chromium as a reference redox system—of reversible or nearly reversible electrode processes. The data have been compared with the redox potentials versus bis(biphenyl)chromium in formamide and N,N-dimethylformamide. Since the dielectric constants of these three solvents differ considerably, models for the correlation of redox potentials with solvent parameters have been evaluated with regard to their ability to predict differences in redox potentials of a given system in these solvents. Purely electrostatic concepts could not account for the observed changes in redox potentials from one solvent to another. Considering interactions of the solvent molecules as donors with cations as acceptors yielded a good correlation between the donor number of the solvents and the redox potentials for cations that were reduced to the respective metal amalgams. The redox potentials of the hexacyanomanganate and hexacyanoferrate anions were found to be a function of the acceptor properties of the solvents.

Solvent effects on redox potentials: Studies in N-methylformamide

The redox behaviour of LiClO 4, NaClO 4, KClO 4, RbClO 4, CsClO 4, TiClO 4, Ba(ClO 4) 2, Cu(CF 3SO 3) 2, Cd(CF 3SO 3) 2, Zn(CF 3SO) 2, Zn(ClO 4) 2·2 H 2O, (Et 4N) 3 Fe(CN) 6, (Bu 4N) 3Fe(CN) 6, (Et 4N) 3 Mn(CN) 6, (Bu 4N) 3 Mn(CN) 6, ferrocene (biscyclopentadienyl-iron(II), bis(biphenyl)chromium tetraphenylborate and perylene has been studied in N-methylformamide employing polarography and cyclic voltammetry. Standard redox potentials have been estimated from polarographic half wave potentials—measured versus bis(biphenyl)chromium as a reference redox system—of reversible or nearly reversible electrode processes. The data have been compared with the redox potentials versus bis(biphenyl)chromium in formamide and N,N-dimethylformamide. Since the dielectric constants of these three solvents differ considerably, models for the correlation of redox potentials with solvent parameters have been evaluated with regard to their ability to predict differences in redox potentials of a given system in these solvents. Purely electrostatic concepts could not account for the observed changes in redox potentials from one solvent to another. Considering interactions of the solvent molecules as donors with cations as acceptors yielded a good correlation between the donor number of the solvents and the redox potentials for cations that were reduced to the respective metal amalgams. The redox potentials of the hexacyanomanganate and hexacyanoferrate anions were found to be a function of the acceptor properties of the solvents.

Current—potential responses for a tetrahemic protein: a method of determining the individual half-wave potentials of cytochrome c3 from desulfovibrio desulfuricans strain Norway

A tetrahemic protein, cytochrome c 3 from Desulfovibrio desulfuricans strain Norway, is studied by differential pulse polarography and linear sweep voltammetry at hanging mercury electrode. A graphical subtractive method applied to the current-potential curves is described and the four individual redox potentials are determined. Both series of experiments lead to two fit sets of values corresponding to reversible electrode processes. The relationship between these redox potentials and the structural data is discussed.

Diagnosis of reversible, quasi-reversible, and irreversible electrode processes with differential pulse polarography

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiagnosis of reversible, quasi-reversible, and irreversible electrode processes with differential pulse polarographyRonald L. Birke, Myung-Hoon. Kim, and Moses. StrassfeldCite this: Anal. Chem. 1981, 53, 6, 852–856Publication Date (Print):May 1, 1981Publication History Published online1 May 2002Published inissue 1 May 1981https://doi.org/10.1021/ac00229a026RIGHTS & PERMISSIONSArticle Views1425Altmetric-Citations115LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (582 KB) Get e-Alerts Get e-Alerts

Current-potential-time relationships in differential pulse polarography: theory of reversible, quasireversible, and irreversible electrode processes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCurrent-potential-time relationships in differential pulse polarography: theory of reversible, quasireversible, and irreversible electrode processesRonald L. BirkeCite this: Anal. Chem. 1978, 50, 11, 1489–1496Publication Date (Print):September 1, 1978Publication History Published online1 May 2002Published inissue 1 September 1978https://doi.org/10.1021/ac50033a027RIGHTS & PERMISSIONSArticle Views208Altmetric-Citations52LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (854 KB) Get e-Alerts Get e-Alerts

A.C. cyclic voltammetry: a digital simulation study of the slow scan limit condition for a reversible electrode process

Rate laws presented to date for analysis of a.c. cyclic voltammetric data have invoked the so-called “slow scan limit approximation” which requires that Δ E ω ≫ v , where Δ E and ω are the applied a.c. potential amplitude and angular frequency, respectively, and v is the d.c. potential scan rate. To provide a more useful guideline for the experimentalist than this qualitative condition, a pure digital simulation approach has been used to compute the a.c. cyclic time domain waveform for a reversible process under small amplitude conditions. The a.c. content of this waveform is extracted by the digital FFT alogirthm. Results of this study are presented here. Among the conclusions reached are more quantitative limitations for the slow scan limit rate laws describing the fundamental and second harmonic responses (approximately 128 a.c. cycles/d.c. cyclic sweep and 512 a.c. cycles/d.c. cyclic sweep, respectively) and an interesting prediction that the latter limitations can be relaxed further by a current waveform subtraction strategy, to as low as about 16 a.c. cycles/d.c. cyclic sweep for the fundamental and second harmonics. The cycles/sweep values assume one triangular wave potential scan of ±200 mV is encompassed.

A.C. Cyclic voltammetry: A digital simulation study of the slow scan limit condition for a reversible electrode process

Rate laws presented to date for analysis of a.c. cyclic voltammetric data have invoked the so-called “slow scan limit approximation” which requires that Δ Eω ≫ v, where Δ E and ω are the applied a.c. potential amplitude and angular frequency, respectively, and v is the d.c. potential scan rate. To provide a more useful guideline for the experimentalist than this qualitative condition, a pure digital simulation approach has been used to compute the a.c. cyclic time domain waveform for a reversible process under small amplitude conditions. The a.c. content of this waveform is extracted by the digital FFT alogirthm. Results of this study are presented here. Among the conclusions reached are more quantitative limitations for the slow scan limit rate laws describing the fundamental and second harmonic responses (approximately 128 a.c. cycles/d.c. cyclic sweep and 512 a.c. cycles/d.c. cyclic sweep, respectively) and an interesting prediction that the latter limitations can be relaxed further by a current waveform subtraction strategy, to as low as about 16 a.c. cycles/d.c. cyclic sweep for the fundamental and second harmonics. The cycles/sweep values assume one triangular wave potential scan of ±200 mV is encompassed.

Shapes of derivative neopolarograms

A derivative neopolarogram is the peaked curve that is generated by semidifferentiation of the current that flows in response to an imposed ramp signal on a stationary electrode. Theory is presented that describes the shapes of such curves for both reversible and irreversible electrode processes at planar and spherical electrodes. Because the shapes are much more complicated in the spherical case, a procedure is discussed for correcting derivative neopolarograms obtained with spherical electrodes.

Shapes of derivative neopolarograms

A derivative neopolarogram is the peaked curve that is generated by semidifferentiation of the current that flows in response to an imposed ramp signal on a stationary electrode. Theory is presented that describes the shapes of such curves for both reversible and irreversible electrode processes at planar and spherical electrodes. Because the shapes are much more complicated in the spherical case, a procedure is discussed for correcting derivative neopolarograms obtained with spherical electrodes.

Theory of a.c. voltammetry at a rotating disk electrode: Part I. A reversible electrode process

A theory of the alternating current response at a rotating disk electrode to a.c. potential perturbation superimposed on d.c. potential is developed for a reversible redox-electrode process. For three typical a.c. potential waves: sinusoidal, rectangular and triangllar waves, the effect of the coupling of the diffusion layer due to a.c. polarization and the hydrodynamic diffusion boundar6 layer on the laternating current is discussed.

Outer-sphere coordination effects on the redox behaviour of the Fe(CN)63−/Fe(CN)64− couple in non-aqueous solvents

The polarographic behaviour of tetra-n-butylammonium hexacyanoferrate(II) has been studied in N-methylpyrrolidinone, N,N-dimethylformamide, acetonitrile, dimethylsulphoxide, N,N-dimethylthioformamide, 1,2-dichloroethane, propanediolcarbonate, nitromethane, ethanol, methanol and acetic acid using tetrabutylammonium perchlorate as supporting electrolyte. A polarographically reversible electrode process was found in all solvents but acetic acid. The large shift in half-wave potentials (vs. bisbiphenylchromium(I) as a reference ion) is interpreted on the basis of donor-acceptor interactions between the hexacyanoferrate ions and solvent molecules and also between the hexacyanoferrate ions and cations of the supporting electrolyte. The considerable difference in half-wave potentials between tetraethylammonium and tetrabutylammonium perchlorate is discussed within the framework of this concept.

Outer-sphere coordination effects on the redox behaviour of the Fe(CN) 63−/Fe(CN) 64− couple in non-aqueous solvents

The polarographic behaviour of tetra-n-butylammonium hexacyanoferrate(II) has been studied in N-methylpyrrolidinone, N,N-dimethylformamide, acetonitrile, dimethylsulphoxide, N,N-dimethylthioformamide, 1,2-dichloroethane, propanediolcarbonate, nitromethane, ethanol, methanol and acetic acid using tetrabutylammonium perchlorate as supporting electrolyte. A polarographically reversible electrode process was found in all solvents but acetic acid. The large shift in half-wave potentials (vs. bisbiphenylchromium(I) as a reference ion) is interpreted on the basis of donor-acceptor interactions between the hexacyanoferrate ions and solvent molecules and also between the hexacyanoferrate ions and cations of the supporting electrolyte. The considerable difference in half-wave potentials between tetraethylammonium and tetrabutylammonium perchlorate is discussed within the framework of this concept.

Comparison of fundamental and second-harmonic a.c., and normal, derivative and differential pulse linear-sweep and stripping voltammetric methods

Linear-sweep and stripping a.c. and pulse voltammetric methods have been compared for a variety of electrodes and electrode processes. Each of the linear-sweep techniques is readily used systematically because, in contrast to d.c. linear-sweep voltammetry, the theory for reversible electrode processes is basically analogous to that for polarography at a dropping mercury electrode. In stripping analysis, some departures are found at a hanging mercury drop electrode because of spherical diffusion effects. For reversible electrode processes, the limits of detection for a.c. and pulse methods are comparable. However, a.c. methods offer advantages over pulse methods in discriminating against irreversible electrode processes and permit the ready use of faster scan rates. Pulse methods are more sensitive for irreversible electrode process. Normal pulse polarography is particularly favourable in minimizing undesirable phenomena arising from adsorption or deposition of material on electrodes.