Dependence of rate constants of heterogeneous electron transfer reactions on viscosity

Zhang, X.; Leddy, Johna; Bard, Allen J.

doi:10.1021/ja00298a054

Cited by 132 publications

(102 citation statements)

References 2 publications

(2 reference statements)

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“…Moreover, considering the dependence of k 0 on solution viscosity, a small k 0 might be expected in an RTIL electrolyte. 49 However, this is based on the assumption that the effect of solution viscosity on k 0 in this medium is similar to that observed in traditional solvents and a recent report has suggested this may not be true. 45 We are currently exploring the effect of RTIL viscosity and electrolyte composition on the heterogeneous electron transfer dynamics of this system.…”

Section: Methodsmentioning

confidence: 95%

Heterogeneous Electron Transfer Kinetics at the Ionic Liquid/Metal Interface Studied Using Cyclic Voltammetry and Scanning Electrochemical Microscopy

Taylor

Fulian

et al. 2008

J. Phys. Chem. B

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The electrochemical behavior of a redox-active, ferrocene-modified ionic liquid (1-ferrocenylmethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in acetonitrile and in an ionic liquid electrolyte (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) is reported. Reversible electrochemical behavior was observed in each electrolyte with responses typical of those for unmodified ferrocene observed in each medium. In the ionic liquid electrolyte, the diffusion coefficient of the redox-active ionic liquid increased by a factor of 5 upon increasing the temperature from 27 to 90°C. The kinetics of electron transfer across the ionic liquid/electrode interface were studied using cyclic voltammetry, and the standard heterogeneous electron transfer rate constant, k 0 was determined to be 4.25 × 10 -3 cm s -1 . Scanning electrochemical microscopy was then also used to probe the heterogeneous kinetics at the interface between the ionic liquid and the solid electrode and conventional kinetic SECM theory was used to determine k 0 . The k 0 value obtained using SECM was higher than that determined using cyclic voltammetry. These results indicate that SECM is a very useful technique for studying electron transfer dynamics in ionic liquids.

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Section: Methodsmentioning

confidence: 95%

Heterogeneous Electron Transfer Kinetics at the Ionic Liquid/Metal Interface Studied Using Cyclic Voltammetry and Scanning Electrochemical Microscopy

Taylor

Fulian

et al. 2008

J. Phys. Chem. B

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“…Indeed, even the oxygen evolving complex of photosystem II experiences up to a ten-fold reduction in catalytic activity in vivo as opposed to in vitro. 340,341 In addition, Bard et al 350 have noted that the heterogeneous electrochemical rate constants for reactants bound in a surface layer are generally 2-3 orders of magnitude smaller than those for the same reactants in the solution phase. In light of this, a direct comparison between surface based and solution based catalysts seems unreasonable.…”

Section: Electrocatalytic Performance -Turnover Frequenciesmentioning

confidence: 99%

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Doyle

Godwin

Brandon

et al. 2013

Phys. Chem. Chem. Phys.

521

565

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This paper presents a review of the redox and electrocatalytic properties of transition metal oxide electrodes, paying particular attention to the oxygen evolution reaction. Metal oxide materials may be prepared using a variety of methods, resulting in a diverse range of redox and electrocatalytic properties. Here we describe the most common synthetic routes and the important factors relevant to their preparation. The redox and electrocatalytic properties of the resulting oxide layers are ascribed to the presence of extended networks of hydrated surface bound oxymetal complexes termed surfaquo groups. This interpretation presents a possible unifying concept in water oxidation catalysis -bridging the fields of heterogeneous electrocatalysis and homogeneous molecular catalysis. In contextOver the past 50 years considerable research efforts have been devoted to the realisation of efficient, economical and renewable energy sources. Metal oxide materials have played a large part in this drive with demonstrated applications at both the research and commercial level. Their use in areas such as batteries, fuel cells and water electrolysis has resulted in the development of materials with a diverse range of structural and chemical properties. In all cases, understanding the fundamental electrochemistry of the material can be invaluable for rational design and optimisation. This review focuses on the redox, charge transport and electrocatalytic properties of transition metal oxide electrodes as they pertain to the electrolytic splitting of water. Particular emphasis is placed on the nature of the active surface which is interpreted in terms of hydrated interlinked oxymetal complexes termed surfaquo groups. In this way, the review seeks to bridge the gap between heterogeneous electrocatalysis and homogeneous molecular catalysis for water oxidation, areas of considerable modern interest and activity.

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“…It is unlikely that the specific interaction of glucose molecules with the metal electrode surface or the SAM terminal groups can be the reasons of observed anomalous viscosity effects. Indeed, Bard and coworkers [22,23] confirmed that sugars are inert at the metal surfaces. Also, they can not interact notably with the terminal hydrophobic SAM groups due to their highly polar character.…”

Section: Resultsmentioning

confidence: 99%

“…According to contemporary theoretical models [3][4][5][6][7][8][9] and recent experimental studies (performed in molecular and/or ionic liquids exploiting chemical redox markers or redoxactive proteins) [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], heterogeneous charge transfer mechanism may display two different intrinsic mechanisms: adiabatic (solvent friction) -at short distances, and nonadiabatic (tunneling) -at long distances, as well as intermediate regime. In all cases the unimolecular rate constant (k o et ) of charge transfer processes, according to the resent theoretical update, can be presented by the eq.…”

Section: Introductionmentioning

confidence: 99%

Charge-Transfer Patterns for [Ru(NH3)6]3+/2+ at SAM Modified Gold Electrodes: Impact of the Permeability of a Redox Probe

Dolidze¹,

Rondinini²,

Vertova³

et al. 2008

TOPCJ

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Electrochemical performance of a [Ru(NH 3 ) 6 ]3+/2+ redox couple at gold electrodes modified by alkanethiol self assembled monolayer (SAM) films of the type [-SH -(CH 2 ) n -CH 3 ] with different number of methylene units (n = 2 to 10) in the presence and absence of glucose additives has been studied using fast scan cyclic and steady-state voltammetry. Specific scatter of measured rate constants caused by enhanced sensitivity of this probe to minor defects of SAMs has been observed in a general agreement with the published data for thicker SAMs (n = 9 to 18). In addition, we have disclosed the anomalous viscosity-imposed drop of the heterogeneous rate constant for the case of Au electrodes modified by thinner n-alkanethiol SAMs (n = 2, 4). Taking into the account the fact of [Ru(NH 3 ) 6 ] 3+/2+ couple's capability to penetrate into the SAM interior, we ascribe the obtained results to the manifestation of the solvent-friction mechanism under the condition where the redox species presumably together with a few of solvating water molecules reside in a SAM's peripheral interior marked by much higher local viscosity (slower dielectric relaxation) compared to the electrolyte solution.

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Dependence of rate constants of heterogeneous electron transfer reactions on viscosity

Cited by 132 publications

References 2 publications

Heterogeneous Electron Transfer Kinetics at the Ionic Liquid/Metal Interface Studied Using Cyclic Voltammetry and Scanning Electrochemical Microscopy

Heterogeneous Electron Transfer Kinetics at the Ionic Liquid/Metal Interface Studied Using Cyclic Voltammetry and Scanning Electrochemical Microscopy

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Charge-Transfer Patterns for [Ru(NH3)6]3+/2+ at SAM Modified Gold Electrodes: Impact of the Permeability of a Redox Probe

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