Measurement of charge passed following application of a potential step-application to the study of electrode reactions and adsorption

Christie, Joseph H.; Laurer, G.R.; Osteryoung, R. A.

doi:10.1016/0022-0728(64)80005-x

Cited by 60 publications

(8 citation statements)

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“…As presented in Table , the intercept calculated by the integrated Cottrell equation is negative. From this, it could be assumed that the pyrrole oxidation process is occurring according to principles described by heterogeneous kinetics. , Moreover, eq describes only kinetics of diffusion. Therefore, in the case of heterogeneous kinetics, the Cottrell equation could be modified as it is presented in eq where k o is the charge-transfer rate constant of the heterogeneous oxidation reaction and H was calculated according to eq where k r is the rate of the reduction reaction and D o is the diffusion coefficient of the oxidized form of the pyrrole.…”

Section: Results and Discussionmentioning

confidence: 99%

“…From this, it could be assumed that the pyrrole oxidation process is occurring according to principles described by heterogeneous kinetics. 23,24 Moreover, eq 1 describes only kinetics of diffusion. Therefore, in the case of heterogeneous kinetics, the Cottrell equation could be modified as it is presented in eq 2 25…”

Section: Resultsmentioning

confidence: 99%

“…The mass of deposited Ppy was calculated using the Sauerbray equation, taking into account that the sensitivity constant of the QCM sensor is equal to 5.6 × 10 −2 Hz•ng −1 • cm 2 . The density of the Ppy film (1.25 g•cm −3 ) was an average value calculated from the literature 24 and was used for the calculation of the increase in Ppy layer thickness during electrochemical polymerization (Figure 4, dotted line).…”

Section: Resultsmentioning

confidence: 99%

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Quartz Crystal Microbalance-Based Evaluation of the Electrochemical Formation of an Aggregated Polypyrrole Particle-Based Layer

Plaušinaitis¹,

Ratautaitė²,

Mikoliūnaitė³

et al. 2015

Langmuir

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Electrochemical quartz crystal microbalance (EQCM) was used for the evaluation of conducting polymer polypyrrole (Ppy), which was formed by a sequence of potential pulses on a Au-plated EQCM disc. The Ppy layer was obtained from freshly prepared polymerization solution consisting of pyrrole that was dissolved in phosphate buffer. The main aim of the study was to determine some aspects of the Ppy layer formation process. The polymerization process was estimated by EQCM and chronoamperometry. The Cottrell equation was used for the integration of total charge that was passing through the electrochemical cell during the formation of the Ppy-based layer. It was found that the charge of the electrical double layer, which was estimated while applying an Anson plot, is negative. From this observation, it could be assumed that the pyrrole oxidation process could be well described by principles of heterogeneous kinetics. The negative value of the electrical double layer was the result of a charge-transfer restriction. This restriction of charge transfer could occur due to partial blocking of the electrode surface by an aggregated Ppy particle-based layer. Quartz crystal motional resistance (R) was taken into account during this research. Ppy layer formation is represented schematically on the basis of the obtained experimental results and analytical data.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Quartz Crystal Microbalance-Based Evaluation of the Electrochemical Formation of an Aggregated Polypyrrole Particle-Based Layer

Plaušinaitis¹,

Ratautaitė²,

Mikoliūnaitė³

et al. 2015

Langmuir

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“…14,15,16,18 If this is a diffusion controlled region, then plots of the flux according to equation (10) should be linear when plotted with t -1 / 2 . Plots of weight loss in Table 1 from 24-336 hr were smoothed by fitting to straight lines, and slopes, intercepts, and R 2 values are given in Table 5.…”

Section: Fick's Law Diffusion Controlled Liquid Transportmentioning

confidence: 99%

“…Equation (30) has been applied to electrochemical experimental data to calculate a diffusion coefficient and a rate of electron transfer. 14 Equation (26) is plotted in the dimensionless form k evap M t /C 0 D evap versus k evap (t/D evap ) 1 / 2 in Figure 6. There is an initial slowly rising portion between 0 and about 1.0 units of k evap (t/D evap ) 1 / 2 , corresponding to the constant rate time frame, followed by an apparent linear increase.…”

Section: Casementioning

confidence: 99%

Mass transport mechanism for the formation of latex-modified epoxy coatings by evaporation from aqueous dispersions

Phillips¹,

Davis²,

Phillips³

2004

J Coat. Technol. Res.

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The transport mechanism for the evaporation of dispersing liquid during the solidification of an epoxy dispersion that had been stabilized to prevent crack formation with a latex dispersion was studied. Aqueous dispersions consisting of an experimentally determined ratio of epoxy resin and nitrile latex were evaporated at 35°C. When the dispersion was evaporated under controlled conditions without forced air flow, a flexible and adherent polymer material formed. The mechanism for coalescence was related to the loss in weight of dispersing liquid during an initial zero order kinetics stage. This was followed by a rate-controlled Fick's law diffusion through the developing coating with subsequent evaporation to the atmosphere. Experimental measurements are compared with theoretical predictions. The rate constant for the zero order time frame is 0.086 ± 0.02 hr -1 . In the second time frame, Ficks's law evaporation rate constant is 0.046 ± 0.017 cm·hr -1 with a diffusion coefficient of 0.00092 ± 0.00051 cm 2 ·hr -1 at 35 ± 1°C and RH 35 ± 7%. Applications for evaporation kinetics are discussed.T he objective of this work is to examine the solution to Fick's law diffusion equation for the formation of polymer coatings by evaporation from water or other aqueous dispersions. Deposition of polymers from waterborne dispersions by dispersing liquid evaporation has application to coating substrates. 1-13 The overall deposition process consists of a number of steps including water transport from the dispersion to the atmosphere, 1-10 coalescing of the dispersed polymer, 4,6,8 evaporation of dispersing water 1,2,4 or dispersing liquid, and solid formation by particle movement within the coalescing coating. 4,6,[9][10][11] The mechanism for water transport is initially surface evaporation, followed by diffusion-controlled mass transport 1-6 through the coating. The initial evaporation is manifested by a linear increase in the amount of liquid evaporated over a relatively short time frame. This is followed by a nonlinear increase where the mass of water evaporated decreases for a longer time.Croll 1 studied heat and mass transfer during drying by measuring the weight loss of latex coatings versus time with a digital balance connected to a microcomputer. Evaporation was controlled at 22 ± 1°C and 50 ± 2% RH; air velocity was 1.8 m·sec -1 or ambient condition. The kinetic data were interpreted as a mechanism consisting of two drying stages: water loss due to evaporation from the surface, followed by additional water loss that is limited by transport of water through a coalescing coating. In a subsequent publication, Croll 2 described an initial stage with a short time frame when the flux is 0.85 of the flux of pure water. In the second stage, water evaporation is limited by the concentration in a wet reaction layer. A derived equation reproduced the drying curves. Adesanya, Nanda, and Beard 3 monitored the moisture weight by a computer system during drying of samples of yellow poplar wood with precise dimensions at temperatures ...

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Über eine Methode zur Bestimmung von Oberflächenreaktionen, die einer reversiblen Elektronenübertragung nachgelagert sind

Koopmann

1968

Ber Bunsenges Phys Chem

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Das Produkt einer reversiblen Elektronenanlagerung soll außer durch Diffusion auch durch eine schnelle chemische Oberflächenreaktion abgeschöpft werden könen. Überwiegt die letztere bei normaler stationärer Versuchsführung, dann kann durch geeignete potentiostatische Impulsmessungen die Verteilung auf die beiden Reaktionswege in theoretisch berechenbarer Weise durch Variation der Impulsdauer verändert werden. Chronocoulometrische Messungen ermöglichen die Bestimmung dieser Verteilung. Mit der angegebenen Theorie kann aus diesen Meßgrößen die Geschwindigkeit der Oberflächenreaktion ermittelt werden. Adsorption der Ausgangssubstanz und des Produktes der Elektronenanlagerung werden berücksichtigt. Die Anwendungsgrenzen der Methode werden angegeben.

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Measurement of charge passed following application of a potential step-application to the study of electrode reactions and adsorption

Cited by 60 publications

References 9 publications

Quartz Crystal Microbalance-Based Evaluation of the Electrochemical Formation of an Aggregated Polypyrrole Particle-Based Layer

Quartz Crystal Microbalance-Based Evaluation of the Electrochemical Formation of an Aggregated Polypyrrole Particle-Based Layer

Mass transport mechanism for the formation of latex-modified epoxy coatings by evaporation from aqueous dispersions

Über eine Methode zur Bestimmung von Oberflächenreaktionen, die einer reversiblen Elektronenübertragung nachgelagert sind

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