Electrode Kinetics of the Ti(IV)/Ti(III) System in Water and in WaterDimethylformamide and WaterDimethyl Sulfoxide Mixed Solvents

1994 ◽  
Vol 59 (6) ◽  
pp. 1279-1286 ◽  
Author(s):  
Libuše Kišová ◽  
Šárka Šotková ◽  
Ivana Komendová
Keyword(s):  
Rate Constants ◽  
Transfer Rate ◽  
Catalytic Effect ◽  
Mixed Solvents ◽  
Electrode Reaction ◽  
Electrode Kinetics ◽  
Electron Transfer Rate ◽  
Standard Rate ◽  
Electrode Coverage ◽  
Kinetics Of

The electron transfer rate constants in the reduction of Ti4+ and oxidation of Ti3+ in water and in water DMF and water DMSO mixtures were determined by square-wave polarography and by analysis of the DC and pulse polarographic curves. The two reactions occur at different potentials due to the rapid consecutive transformation of the primary product of the electrode reaction. Thus the rate constants are no standard rate constants, and depend on the method employed. The effect of the organic co-solvent varies for both reactions as a consequence of dependence of the degree of electrode coverage on potential. Generally, the adsorbed organic substance exerts an accelerating catalytic effect.

scholarly journals The effects of the chemical environment of menaquinones in lipid monolayers on mercury electrodes on the thermodynamics and kinetics of their electrochemistry

2021 ◽  
Author(s):  
Karuppasamy Dharmaraj ◽  
Dirk Dattler ◽  
Heike Kahlert ◽  
Uwe Lendeckel ◽  
Felix Nagel ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Transfer Rate ◽  
Chemical Environment ◽  
Lipid Monolayers ◽  
Redox Potentials ◽  
Electron Transfer Rate ◽  
Thermodynamics And Kinetics ◽  
Mercury Electrodes ◽  
Kinetics Of

AbstractThe effects of the chemical environment of menaquinones (all-trans MK-4 and all-trans MK-7) incorporated in lipid monolayers on mercury electrodes have been studied with respect to the thermodynamics and kinetics of their electrochemistry. The chemical environment relates to the composition of lipid films as well as the adjacent aqueous phase. It could be shown that the addition of all-trans MK-4 to TMCL does not change the phase transition temperatures of TMCL. In case of DMPC monolayers, the presence of cholesterol has no effect on the thermodynamics (formal redox potentials) of all-trans MK-7, but the kinetics are affected. Addition of an inert electrolyte (sodium perchlorate; change of ionic strength) to the aqueous phase shifts the redox potentials of all-trans MK-7 only slightly. The formal redox potentials of all-trans MK-4 were determined in TMCL and nCL monolayers and found to be higher in nCL monolayers than in TMCL monolayers. The apparent electron transfer rate constants, transfer coefficients and activation energies of all-trans MK-4 in cardiolipins have been also determined. Most surprisingly, the apparent electron transfer rate constants of all-trans MK-4 exhibit an opposite pH dependence for TMCL and nCL films: the rate constants increase in TMCL films with increasing pH, but in nCL films they increase with decreasing pH. This study is a contribution to understand environmental effects on the redox properties of membrane bond redox systems. Graphical abstract

Electrode kinetics of the system V(III)/V(II) in aqueous dimethylsulphoxide

1991 ◽  
Vol 56 (1) ◽  
pp. 90-95 ◽  
Author(s):  
Libuše Kišová ◽  
Libor Reichstädter ◽  
Jaro Komenda
Keyword(s):  
Organic Solvent ◽  
Double Layer ◽  
Rate Constants ◽  
Electrode Surface ◽  
Reaction Rate ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Electrode Kinetics ◽  
Kinetics Of ◽  
Lower Basicity

The rate constants for the reduction of V(III) and oxidation of V(II) were measured on a mercury electrode in water and water-dimethylsulphoxide mixtures. Their dependance on the concentration of DMSO differs from that in mixtures of water with an organic solvent of lower basicity. This can be attributed to the existence of different solvates of vanadium in solutions and to different values of the rate constant for these solvates on the electrode surface at different coverages with the organic component. The influence of DMSO both in the primary solvation sphere and in the electrode double layer on the electrode reaction rate is discussed.

A Comparison between Interfacial Electron-Transfer Rate Constants at Metallic and Graphite Electrodes

2006 ◽  
Vol 110 (39) ◽  
pp. 19433-19442 ◽  
Author(s):  
William J. Royea ◽  
Thomas W. Hamann ◽  
Bruce S. Brunschwig ◽  
Nathan S. Lewis
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Transfer Rate ◽  
Interfacial Electron Transfer ◽  
Electron Transfer Rate ◽  
Graphite Electrodes

Calculation of Electron Transfer Rate Constants from Spectra in Re(I) Chromophore−Quencher Complexes

1996 ◽  
Vol 118 (40) ◽  
pp. 9782-9783 ◽  
Author(s):  
Juan Pablo Claude ◽  
Darryl S. Williams ◽  
Thomas J. Meyer
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Transfer Rate ◽  
Electron Transfer Rate

Efficient photoinduced electron transfer between C60/C70 and zinc octaethylporphyrin studied by nanosecond laser photolysis method

2000 ◽  
Vol 04 (06) ◽  
pp. 591-598 ◽  
Author(s):  
MOHAMED E. EL-KHOULY ◽  
MAMORU FUJITSUKA ◽  
OSAMU ITO
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Photoinduced Electron Transfer ◽  
Transfer Rate ◽  
Transient Absorption ◽  
Laser Light ◽  
Solvent Polarity ◽  
Nanosecond Laser ◽  
Electron Transfer Rate ◽  
Absorption Bands

Photoinduced electron-transfer processes between C 60 or C 70 and zinc octaethylporphyrin ( ZnOEP ) have been studied in polar solvents with the nanosecond laser flash photolysis method, observing the transient absorption spectra in the visible and near-IR regions. By the predominant excitation of ZnOEP with 532 nm laser light the transient absorption bands of 3 ZnOEP * decayed, accompanied by the appearance of the transient absorption bands of [Formula: see text] and [Formula: see text]. By the predominant excitation of C 60 and C 70 with 610 nm laser light the decays of [Formula: see text] and [Formula: see text] were observed, accompanied by the appearance of [Formula: see text] and [Formula: see text]. The electron transfer rate constants (k et ) and the quantum yields (Φ et ) of [Formula: see text] and [Formula: see text] formation via 3 ZnOEP * and [Formula: see text] or [Formula: see text] have been evaluated. These values increase with the solvent polarity; in polar benzonitrile these values are higher than for other porphyrins such as zinc tetraphenylporphyrin. The back electron transfer rate constants were evaluated from the decays of [Formula: see text] and [Formula: see text], which also show a solvent polarity dependence.

Electrode kinetics of Eu3+/Eu2+ reaction by cyclic voltammetry

1982 ◽  
Vol 47 (7) ◽  
pp. 1773-1779 ◽  
Author(s):  
T. P. Radhakrishnan ◽  
A. K. Sundaram
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Outer Sphere ◽  
Electrode Reaction ◽  
Transfer Reactions ◽  
Cyclic Voltammetric ◽  
Edta Solution ◽  
Kinetics Of ◽  
Activated Complex ◽  
Good Agreement

The paper is a detailed study of the cyclic voltammetric behaviour of Eu3+ at HMDE in molar solutions of KCl, KBr, KI, KSCN and in 0.1M-EDTA solution with an indigenously built equipment. The computed values of the rate constants at various scan rates show good agreement with those reported by other electrochemical methods. In addition, the results indicate participation of a bridged activated complex in the electron-transfer step, the rate constants showing the trend SCN- > I- > Br- > Cl- usually observed for bridging order of these anions in homogeneous electron-transfer reactions. The results for Eu-EDTA system, however, indicate involvement of an outer sphere activated complex in the electrode reaction.

Influence of Aqueous Mixtures of Amides on the Kinetics of Electro Reduction of Ni(II) and Co(II) at d. m. e.

1975 ◽  
Vol 30 (11-12) ◽  
pp. 859-861 ◽  
Author(s):  
S. K. Jha ◽  
S. Jha ◽  
S. N. and
Keyword(s):  
Rate Constants ◽  
Electrode Potential ◽  
Gradual Decrease ◽  
Electrode Kinetics ◽  
Aqueous Mixtures ◽  
Aqueous Mixture ◽  
Kinetics Of ◽  
Remarkable Agreement ◽  
Amide Content

Electroreduction of Ni(II) and Co(II) has been carried out in aqueous mixtures of formamide, acetamide and urea. Electrode kinetics in terms of theories of irreversible waves have been studied. After calculating the rate constants by DELAHAY1 and Kou-TECKY2 treatments separately their variation with electrode potential has been used to calculate the product ‘ana’. The rate constants and ‘ana’ calculated from two different approaches show remarkable agreement. `ana’ records a gradual decrease with increasing amide content of the aqueous mixture.

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