The voltammetry is an electrochemical method which provides the value of the current through the investigated sample under time-variable polarisation (voltage).

Cyclic Voltammetry (CV) is a particular version of voltametry making use of repetitive symmetrical voltage ramps in order to promote complementary electrochemical processes and to evaluate them (see Fig. 1a).

The acquired experimental parameter - that is, the current – mainly contains two superposed contributions: the current charging the capacitance of the investigated system and the current due to the electrochemical processes occurring at the electrode(s). The capacitive current component is proportional to the voltage sweep (scan) rate having the double layer capacitance as proportionality constant (see the purple curve plotted in Fig. 1b).

Charge transfer reactions or specific chemisorption processes at the electrodes result in faradaic responses leading to the formation of current peaks (as shown by the royal curve in Fig. 1b. [Bard2001, Horter2008]

Fig. 1. a. Typical CV scan voltage. b. The current response: 1st scan only the capacitive component; 2nd scan presents contributions from the electrode reactions.

In gas sensor application the cyclic voltammetry allows to correlate the amount of analyte absorbed in the sensing element with the analyte partial pressure in the gas phase by using, for example, the change of the diffusion current. Also the capacitive current dependency on the scan rate can give useful information on the gaseous analyte sorption, similar to that obtained through electrochemical impedance spectroscopy at low frequency. A relevant example is the electrochemical response of the polyacrylic acid (PAA) films to the surrounding humidity due to water related electro-active species (see Fig. 2), [Horter2008, Hoerter2008a]

Fig. 2. CV response of PAA to humidity and the influence of the background ammonia (left). The dependency of the capacitive current on the scan rate indicates the complex structure of the double layer which can not be described by a single capacitance (right).


[Bard2001] Larry R. Bard, Allen J. Faulkner, Electrochemical methods : fundamentals and applications, Wiley, New York, 2. ed. edition, 2001.

[Horter2008] Melanie Hörter, Influence of ammonia and water sorption on the chemical and electrochemical properties of polyacrylic acid and its derivates. PhD thesis, Eberhard-Karls Universität Tübingen, 2008.

[Hoerter2008a] M. Hörter, A. Oprea, N. Bârsan, and U. Weimar, Kelvin Probe measurements of polymer coated gold substrates: Mechanism studies. SENSORS AND ACTUATORS B-CHEMICAL, 134(1):266–272, AUG 28 2008.