Cyclic Voltammetry
Also known as: CV, cyclic voltammetry, electrochemistry
Cyclic Voltammetry (CV) is an electrochemical technique that measures redox reactions by varying the voltage applied to an electrode and monitoring the resulting current. Developed by Nicholson and Shain in 1964, CV is one of the most widely used electrochemical methods, providing rapid information about the redox potentials and electron-transfer kinetics of molecules and materials.
Key highlights
- Rapid screening: complete voltammogram acquired in seconds to minutes
- Multi-electron information: multiple redox peaks in one scan reveal all accessible redox couples
- Kinetic information: electron-transfer rate constants can be extracted from peak shapes
- Reversibility assessment: reversible vs. irreversible reactions distinguished by peak separation
Intuition
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How it works
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When to use it
Apply CV to characterize any redox-active species: organic molecules, metal complexes, proteins with redox centers, and electrodes. CV is ideal for quickly screening reaction conditions and assessing electron-transfer kinetics. Assumes the species is stable during the voltage sweep and that the electrode is stable at the applied potentials.
Strengths & limitations
- Rapid screening: complete voltammogram acquired in seconds to minutes
- Multi-electron information: multiple redox peaks in one scan reveal all accessible redox couples
- Kinetic information: electron-transfer rate constants can be extracted from peak shapes
- Reversibility assessment: reversible vs. irreversible reactions distinguished by peak separation
- Current is measured not potential; weak signals from low-concentration samples are noisy
- Electrode fouling: electrochemical reactions can deposit products that coat the electrode, blocking subsequent reactions
- Mass-transport limited: at fast scan rates, diffusion cannot keep pace with voltage sweep, distorting peaks
- Potential window limited: electrodes corrode or water electrolyzes at extreme potentials
Common pitfalls
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Applications
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Frequently asked
What information does the separation between oxidation and reduction peaks provide?
Peak separation (ΔEp) indicates reversibility. For a reversible single-electron transfer, ΔEp = 59 mV. Larger separations indicate kinetic barriers (slow electron transfer or chemical complications following electron transfer). Very large separations suggest irreversible reactions where the oxidized and reduced forms do not directly interconvert.
How does scan rate affect cyclic voltammetry?
Faster scan rates shift peak potentials (typically 59 mV per 10-fold increase in scan rate for reversible reactions) and increase peak currents. Multiple scan rates distinguish reversible from irreversible reactions and reveal diffusion-controlled versus kinetically limited processes.
What is the reference electrode and why is it needed?
The reference electrode maintains a constant, known potential against which the working electrode's potential is measured. Common choices include saturated calomel electrode (SCE, 0.244 V vs. SHE) and silver/silver chloride (Ag/AgCl, 0.197 V vs. SHE). Without a reference, there is no absolute potential scale.
Sources
- 1.Nicholson, R. S., & Shain, I. (1964). Electroanalytical chemistry. Analytical Chemistry, 36(4), 706-723.
- 2.Bard, A. J., & Faulkner, L. R. (2001). Electrochemical Methods: Fundamentals and Applications. John Wiley & Sons, 2nd edition.
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Cite this page
ScholarGate. (2026, June 3). Cyclic Voltammetry. ScholarGate. https://scholargate.app/spectroscopy/cyclic-voltammetry