Discrimination of Inner- and Outer-Sphere Electrode Reactions by Cyclic Voltammetry Experiments

2013 ◽  
Vol 90 (6) ◽  
pp. 778-781 ◽  
Author(s):  
Sachiko Tanimoto ◽  
Akio Ichimura
Keyword(s):  
Cyclic Voltammetry ◽  
Outer Sphere ◽  
Electrode Reactions

scholarly journals Electro-deposition and re-oxidation of carbon in carbonate-containing molten salts

2014 ◽  
Vol 172 ◽  
pp. 105-116 ◽  
Author(s):  
Happiness V. Ijije ◽  
Richard C. Lawrence ◽  
Nancy J. Siambun ◽  
Sang Mun Jeong ◽  
Daniel A. Jewell ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Molten Salts ◽  
Carbon Deposition ◽  
Solid Carbon ◽  
Partial Reduction ◽  
Constant Voltage ◽  
Electro Deposition ◽  
Electrode Reactions ◽  
Electrode Cell ◽  
Potential Applications

The electrochemical deposition and re-oxidation of solid carbon were studied in CO32− ion-containing molten salts (e.g. CaCl2–CaCO3–LiCl–KCl and Li2CO3–K2CO3) at temperatures between 500 and 800 °C under Ar, CO2 or N2–CO2 atmospheres. The electrode reactions were investigated by thermodynamic analysis, cyclic voltammetry and chronopotentiometry in a three-electrode cell under various conditions. The findings suggest that the electro-reduction of CO32− is dominated by carbon deposition on all three tested working electrodes (Ni, Pt and mild steel), but partial reduction to CO can also occur. Electro-re-oxidation of the deposited carbon in the same molten salts was investigated for potential applications in, for example, direct carbon fuel cells. A brief energy and cost analysis is given based on results from constant voltage electrolysis in a two-electrode cell.

scholarly journals Composition of outer sphere cations and the charge transfer kinetics of the Ti (IV)/Ti (III) redox couple in the KCl—KF melt.

2020 ◽  
Vol 11 (3-2020) ◽  
pp. 33-38
Author(s):  
D.A. Vetrova ◽  
◽  
S.A. Kuznetsov ◽  
Keyword(s):  
Cyclic Voltammetry ◽  
Charge Transfer ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Outer Sphere ◽  
Redox Couple ◽  
Alkaline Earth Metal ◽  
Charge Transfer Process ◽  
Cyclic Voltammetry Method ◽  
Kinetics Of

The charge transfer kinetics for the redox couple Ti(IV)/Ti(III) in the KCl —KF (10 wt. %) —K2TiF6was studied by cyclic voltammetry method. The influence of strongly polarizing Mg2+, Ca2+, Sr2+and Ba2+cations on the kinetics of charge transfer for the Ti(IV)/Ti(III) redox couple upon their introduction into the initial melt, was studied. The activation energies of the charge transfer process for the initial melt and for the melt with the addition of alkaline earth metal cations were calculated.

scholarly journals Estimating the Electrochemically Active Area: Revisiting a Basic Concept in Electrochemistry

2021 ◽  
Author(s):  
Dyovani Coelho ◽  
Giuliana Luiz ◽  
Sergio Machado
Keyword(s):  
Carbon Nanotubes ◽  
Surface Roughness ◽  
Cyclic Voltammetry ◽  
Platinum Electrode ◽  
Outer Sphere ◽  
Active Area ◽  
Redox Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electrochemically Active

The well-known electrochemical probe Fe(CN)63-/Fe(CN)64- is widely used for estimating the electrochemically active area of electrodes modified with carbon nanotubes, conductive polymers, enzymes, etc. In this study, we used the platinum electrode, smooth or platinized with different roughness factors, to demonstrate that such a redox couple fails to respond to a surface roughness variation. We determined the roughness factors of the Pt surfaces by atomic force microscopy (AFM) images, which yielded values between 2.72 and 25.91. Almost the same values were found by using the charge of the hydrogen monolayer desorption obtained from steady-state cyclic voltammetry experiments performed in an acid medium. They were then compared with those provided by peak current in voltammetry or chronoamperometry with Fe(CN)6 3-/Fe(CN)64- which all yielded values nearly to one. Such comparison demonstrates that the electrochemical behavior of the redox probe is an outer sphere reaction with a quite small interaction with the electrode surface, thus not being suitable to be related with active areas.

scholarly journals Theory of staircase cyclic voltammetry of two electrode reactions coupled by a chemical reaction

2019 ◽  
Vol 51 (3) ◽  
pp. 348-357
Author(s):  
Š. Komorsky-Lovrić ◽  
M. Lovrić
Keyword(s):  
Cyclic Voltammetry ◽  
Chemical Reaction ◽  
Forward Rate ◽  
Electrode Reactions ◽  
Reversible Chemical Reaction ◽  
Ece Mechanism ◽  
Forward Rate Constant ◽  
Thermodynamic And Kinetic Parameters ◽  
The Stability ◽  
Kinetics Of

Two reversible electrode reactions that are connected by either reversible or totally irreversible chemical reactions are theoretically analysed by staircase cyclic voltammetry. The dependence of peak potentials on the thermodynamic and kinetic parameters is calculated. If the mechanism is permanently in equilibrium, the stability constant of the reversible chemical reaction can be determined. Furthermore, the critical kinetic parameter is determined and its application to the measurement of the forward rate constant of the chemical reaction is demonstrated. Also, the influence of the kinetics of electrode reactions is discussed. Keywords: ECE mechanism; Cyclic voltammetry; Theory

Electrochemical Reduction of [Ni(Mebpy)3]2+. Elucidation of the Redox Mechanism by Cyclic Voltammetry and Steady-State Voltammetry in Low Ionic Strength Solutions.

2020 ◽  
Author(s):  
Koushik Barman ◽  
Martin A. Edwards ◽  
David P. Hickey ◽  
Christopher Sandford ◽  
Yinghua Qiu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Steady State ◽  
Ionic Strength ◽  
Outer Sphere ◽  
Oxidation States ◽  
Bulk Solution ◽  
Redox Mechanism ◽  
Predominant Species ◽  
Low Ionic Strength

<p>Bipyridine complexes of Ni are used as catalysts in a variety of reductive transformations. Here, the electroreduction of [Ni(Mebpy)<sub>3</sub>]<sup>2+</sup> (Mebpy = 4,4’-dimethyl-2,2’-bipyridine) in dimethylformamide is reported, with the aim of determining the redox mechanism and oxidation states of products formed under well-controlled electrochemical conditions. Results from cyclic voltammetry, steady-state voltammetry (SSV) and chronoamperometry demonstrate that [Ni(Mebpy)<sub>3</sub>]<sup>2+</sup> undergoes two sequential 1<i>e</i> reductions at closely separated potentials (<i>E</i><sup>0’</sup><sub>1 </sub>= -1.06 ± 0.01 V and <i>E</i><sup>0<i>’</i></sup><sub>2 </sub>=<sub> </sub>-1.15 ± 0.01 V vs Ag/AgCl (3.4 M KCl)). Homogeneous comproportionation to generate [Ni(Mebpy)<sub>3</sub>]<sup>+ </sup>is demonstrated in SSV experiments in low ionic strength solutions. The comproportionation rate constant is determined to be > 10<sup>6</sup> M<sup>-1</sup>s<sup>-1</sup>, consistent with rapid outer-sphere electron transfer. Consequentially, on voltammetric time scales, the 2<i>e</i> reduction of [Ni(Mebpy)<sub>3</sub>]<sup>2+</sup> results in formation of [Ni(Mebpy)<sub>3</sub>]<sup>1+</sup> as the predominant species released into bulk solution. We also demonstrate that [Ni(Mebpy)<sub>3</sub>]<sup>0</sup><sub> </sub>slowly loses a Mebpy ligand (~10 s<sup>-1</sup>).</p>

Electrochemical Reduction of [Ni(Mebpy)3]2+. Elucidation of the Redox Mechanism by Cyclic Voltammetry and Steady-State Voltammetry in Low Ionic Strength Solutions.

2020 ◽  
Author(s):  
Koushik Barman ◽  
Martin A. Edwards ◽  
David P. Hickey ◽  
Christopher Sandford ◽  
Yinghua Qiu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Steady State ◽  
Ionic Strength ◽  
Outer Sphere ◽  
Oxidation States ◽  
Bulk Solution ◽  
Redox Mechanism ◽  
Predominant Species ◽  
Low Ionic Strength

<p>Bipyridine complexes of Ni are used as catalysts in a variety of reductive transformations. Here, the electroreduction of [Ni(Mebpy)<sub>3</sub>]<sup>2+</sup> (Mebpy = 4,4’-dimethyl-2,2’-bipyridine) in dimethylformamide is reported, with the aim of determining the redox mechanism and oxidation states of products formed under well-controlled electrochemical conditions. Results from cyclic voltammetry, steady-state voltammetry (SSV) and chronoamperometry demonstrate that [Ni(Mebpy)<sub>3</sub>]<sup>2+</sup> undergoes two sequential 1<i>e</i> reductions at closely separated potentials (<i>E</i><sup>0’</sup><sub>1 </sub>= -1.06 ± 0.01 V and <i>E</i><sup>0<i>’</i></sup><sub>2 </sub>=<sub> </sub>-1.15 ± 0.01 V vs Ag/AgCl (3.4 M KCl)). Homogeneous comproportionation to generate [Ni(Mebpy)<sub>3</sub>]<sup>+ </sup>is demonstrated in SSV experiments in low ionic strength solutions. The comproportionation rate constant is determined to be > 10<sup>6</sup> M<sup>-1</sup>s<sup>-1</sup>, consistent with rapid outer-sphere electron transfer. Consequentially, on voltammetric time scales, the 2<i>e</i> reduction of [Ni(Mebpy)<sub>3</sub>]<sup>2+</sup> results in formation of [Ni(Mebpy)<sub>3</sub>]<sup>1+</sup> as the predominant species released into bulk solution. We also demonstrate that [Ni(Mebpy)<sub>3</sub>]<sup>0</sup><sub> </sub>slowly loses a Mebpy ligand (~10 s<sup>-1</sup>).</p>

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