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.

voltammetry: factors affecting measurements

Voltammetry: Factors Affecting Measurements

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 divided into two types. The current generated due to the reduction of the analyte is called cathodic current, and it carries a positive charge. In contrast, the current produced by analyte oxidation is known as an anodic current, and it has a negative charge. The applied potential at the working electrode determines the faradaic current flow, and the magnitude of faradic current depends on the rate of the resulting oxidation or reduction reaction at the electrode surface.
In addition, various mass transport reaction 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. During diffusion, ions or molecules are transported from a region of high concentration to a region of low concentration, and the effect of diffusion on the mass transport rate is time-dependent. It is known as convection if a mechanical means is used to carry reactants toward the electrode and remove products from the electrode. It is called migration if the charged analyte particles are attracted or repelled by electrodes.
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 charging current produced by the changes in electrode potential must be accounted for before measuring the Faradaic component.&#160;

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

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Analytical Chemistry

Unit 1

Electrochemical Analyses and Redox Titration

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KEY TERMS AND CONCEPTS

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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