Cyclic voltammetry
A voltammetric method using cyclical potential sweeps to study redox processes.
Cyclic voltammetry (CV) is a type of voltammetric measurement in electrochemistry where the potential of the working electrode is ramped linearly versus time in cyclical phases. Unlike in linear sweep voltammetry, after the set potential is reached, the working electrode's potential is ramped in the opposite direction to return to the initial potential, and these cycles are repeated until a cyclic steady state is achieved. The current at the working electrode is plotted versus the voltage to yield the cyclic voltammogram, a technique generally used to study the electrochemical properties of an analyte in solution or adsorbed onto the electrode, and to quantify electrochemical surface area of catalysts.
- field
- Electrochemistry
- known_for
- Cyclic voltammetry (CV) as a voltammetric measurement technique
- type
- Analytical technique
- application
- Studying redox properties of analytes and quantifying catalyst surface area
- key_equation
- Randles–Sevcik equation
Lore & Background
In cyclic voltammetry, the electrode potential is ramped linearly versus time in cyclical phases, with the rate of voltage change known as the scan rate (V/s). In a standard three-electrode cell, potential is measured between the working and reference electrodes, while current is measured between the working and counter electrodes. During the initial forward scan, an increasingly oxidative potential is applied, and anodic current increases due to charging of the electric double layer, with a spike from oxidation of the analyte when the correct potential is reached. The current then decreases as the oxidable analyte is depleted near the electrode surface due to mass transport limitations.
Reader's Guide
Cyclic voltammetry is a foundational technique in electrochemistry, valued for its ability to probe the redox behavior of analytes in solution or adsorbed on electrodes. The resulting cyclic voltammogram often has a characteristic 'duck-like' shape, and comparing the oxidation and reduction portions allows determination of electrochemical parameters such as redox potential and reversibility. For reversible couples, the peak current is proportional to the square root of the scan rate, as described by the Randles–Sevcik equation, indicating diffusion-limited current. The technique is also used to quantify the electrochemical surface area of catalysts. Its utility depends on the analyte being redox active within the potential window, and it can reveal information about electron transfer kinetics and coupled chemical reactions, making it essential for characterizing electrochemical systems.
Did You Know?
- In cyclic voltammetry, the potential is ramped linearly in both forward and reverse directions, unlike linear sweep voltammetry.
- The difference in peak potentials (ΔEp) for an ideal reversible 1e- couple is 57 mV, though experimental values often approach 70 or 80 mV.
- For adsorbed species at slow scan rates, there is ideally no peak separation, and peak current is proportional to scan rate.
- The Randles–Sevcik equation describes the relationship where peak current is proportional to the square root of the scan rate for diffusion-limited processes.
Frequently Asked Questions
Who is Cyclic voltammetry?
Cyclic voltammetry is a voltammetric analytical technique in electrochemistry that drives a working electrode through repeating forward-and-backward linear potential ramps. It is the standard method for probing the redox behavior of dissolved species and for characterizing electrode surfaces.
What are Cyclic voltammetry's powers/role?
Its core ability is to expose the redox properties of an analyte by recording the current response as the electrode potential sweeps back and forth. It is also routinely used to quantify the electrochemically active surface area of catalysts.
How does Cyclic voltammetry's story end?
The technique keeps cycling its potential sweep until a cyclic steady state is reached, at which point the current-versus-voltage trace—the cyclic voltammogram—stabilizes and the measurement is complete.
Why is Cyclic voltammetry important?
It delivers a fast, information-rich fingerprint of electron-transfer kinetics, diffusion coefficients, and interfacial interactions without consuming the analyte. That makes it indispensable in battery research, catalyst development, and mechanistic redox studies.
What is Cyclic voltammetry's signature equation?
The Randles–Sevcik equation links the peak current on a voltammogram to the scan rate, analyte concentration, and diffusion coefficient. It is the go-to relationship for extracting quantitative kinetic and transport parameters from a CV experiment.
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