Name: voltammetry and faradaic current
Uploaded: 2024-12-05T18:31:57.000Z
Duration: 1 min 21 s
Channel: JoVE

Faradaic current is the current produced at working and auxiliary electrodes due to the oxidation or reduction of an analyte.
The cathodic current produced by analyte reduction carries a positive charge, whereas the anodic current produced by analyte oxidation is negatively charged.
The faradaic current flow is governed by the applied potential at the working electrode, and its magnitude depends on the rate of the resulting oxidation or reduction reaction at the electrode surface.
Mass transport processes like diffusion, migration, and convection affect the faradaic current by facilitating the movement of ions or molecules from the electrode surface to the bulk solution and vice versa.
The rate of mass transport also influences the current. If the rate of electron transport kinetics is fast, the redox reaction is at equilibrium, and the system is electrochemically reversible.
In contrast, when the rate of electron transport kinetics is slow, the system is treated as electrochemically irreversible.
Finally, the Nonfaradaic current produced by changes in electrode potential must be accounted for before measuring the faradaic component.

voltammetrie: factoren die metingen beïnvloeden

Voltammetry: Factors Affecting Measurements

Een stroom die wordt geproduceerd door de redoxreacties van de analyt bij de werk- en hulpelektroden wordt een Faraday stroom genoemd. De reactie kan worden onderverdeeld in twee typen. De stroom die wordt gegenereerd door de reductie van de analyt wordt kathodische stroom genoemd en draagt ​​een positieve lading. Daarentegen staat de stroom die wordt geproduceerd door de oxidatie van de analyt bekend als een anodische stroom en heeft deze een negatieve lading. Het toegepaste potentieel bij de werkelektrode bepaalt de Faraday stroom en de grootte van de Faraday stroom is afhankelijk van de snelheid van de resulterende oxidatie- of reductiereactie op het elektrodeoppervlak.


Bovendien beïnvloeden verschillende massatransportreactieprocessen zoals diffusie, migratie en convectie de Faraday stroom door de beweging van ionen of moleculen van het elektrodeoppervlak naar de bulkoplossing en vice versa te vergemakkelijken. Tijdens diffusie worden ionen of moleculen getransporteerd van een gebied met een hoge concentratie naar een gebied met een lage concentratie en het effect van diffusie op de massatransportsnelheid is tijdsafhankelijk. Het staat bekend als convectie als een mechanisch middel wordt gebruikt om reactanten naar de elektrode te transporteren en producten van de elektrode te verwijderen. Het wordt migratie genoemd als de geladen analytdeeltjes worden aangetrokken of afgestoten door elektroden.


De snelheid van massatransport beïnvloedt ook de stroom. Als de snelheid van elektronentransportkinetiek snel is, is de redoxreactie in evenwicht en is het systeem elektrochemisch omkeerbaar. Daarentegen wordt het systeem behandeld als elektrochemisch onomkeerbaar wanneer de snelheid van elektronentransportkinetiek langzaam is. Ten slotte moet de niet-Faradaïsche laadstroom die wordt geproduceerd door de veranderingen in elektrodepotentiaal worden meegerekend voordat de Faradaïsche component wordt gemeten.

Voltammetrie: factoren die metingen beïnvloeden

A current produced due to the redox reactions of the analyte at the working and auxiliary electrodes is called a faradaic current. The reaction can be ...

voltammetry-factors-affecting-measurements

Education

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Analytical Chemistry

Analytische chemie

Unit 1

Electrochemical Analyses and Redox Titration

Elektrochemische analyses en redox-titratie

electrochemical-analyses-and-redox-titration

KEY TERMS AND CONCEPTS

KERNTERMEN EN CONCEPTEN

voltammetry and faradaic current

Voltammetry measures faradaic current, which is the current created by redox reactions of an analyte at the working and auxiliary electrodes. The current from reduction is called cathodic current and carries a positive charge. The current from oxidation is called anodic current and has a negative charge.

The applied potential at the working electrode controls the flow of faradaic current. The size of that current depends on how fast the oxidation or reduction reaction occurs at the electrode surface. Mass transport also changes the current because it moves ions or molecules between the electrode surface and the bulk solution.

Diffusion, migration, and convection are the main mass transport processes. Diffusion moves particles from high concentration to low concentration, and its effect changes with time. Convection uses mechanical motion to carry reactants toward the electrode and move products away, while migration happens when charged analyte particles are attracted or repelled by electrodes.

The rate of mass transport also affects the measured current. When electron transport kinetics are fast, the redox reaction stays at equilibrium and the system is electrochemically reversible. When electron transport kinetics are slow, the system is electrochemically irreversible.

A nonfaradaic charging current must also be considered before the faradaic component is measured. This charging current comes from changes in electrode potential. It does not arise from the analyte redox reaction, so it must be separated from the current of interest.

Voltammetry and Faradaic Current

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Voltammetry measures faradaic current, which is the current created by redox reactions of an analyte at the working and auxiliary electrodes. The current from reduction is called cathodic current and carries a positive charge. The current from oxidation is called anodic current and has a negative charge. The applied potential at the working electrode controls the flow of faradaic current. The size of that current depends on how fast the oxidation or reduction reaction occurs at the electrode...

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key terms and concepts

Learn how faradaic current in voltammetry depends on redox reactions, mass transport, electron-transfer rate, and charging current at the electrodes.

Voltammetry and Faradaic Current | JoVE K12

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Voltammetry and Faradaic Current

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