Chronoamperometry

Double-pulsed chronoamperometry waveform showing integrated region for charge determination.

In electrochemistry, chronoamperometry is an analytical technique in which the electric potential of the working electrode is stepped and the resulting current from faradaic processes occurring at the electrode (caused by the potential step) is monitored as a function of time. The functional relationship between current response and time is measured after applying single or double potential step to the working electrode of the electrochemical system. Limited information about the identity of the electrolyzed species can be obtained from the ratio of the peak oxidation current versus the peak reduction current. However, as with all pulsed techniques, chronoamperometry generates high charging currents, which decay exponentially with time as any RC circuit. The Faradaic current - which is due to electron transfer events and is most often the current component of interest - decays as described in the Cottrell equation. In most electrochemical cells, this decay is much slower than the charging decay-cells with no supporting electrolyte are notable exceptions. Most commonly a three-electrode system is used. Since the current is integrated over relatively longer time intervals, chronoamperometry gives a better signal-to-noise ratio in comparison to other amperometric techniques.

Scheme of chronoamperometry instrument

[1][2][3]

There are two types of chronoamperometry that are commonly used: controlled-potential chronoamperometry and controlled-current chronoamperometry. Before running controlled-potential chronoamperometry, cyclic voltammetries are run to determine the reduction potential of the analytes. Generally, chronoamperometry uses fixed-area electrodes, which are suitable for studying electrode processes of coupled chemical reactions, especially the reaction mechanism of organic electrochemistry.[4]

  1. ^ Kissinger, Peter; William R. Heineman (1996-01-23). Laboratory Techniques in Electroanalytical Chemistry, Second Edition, Revised and Expanded (2 ed.). CRC. ISBN 978-0-8247-9445-3.
  2. ^ Bard, Allen J.; Larry R. Faulkner (2000-12-18). Electrochemical Methods: Fundamentals and Applications (2 ed.). Wiley. ISBN 978-0-471-04372-0.
  3. ^ Zoski, Cynthia G. (2007-02-07). Handbook of Electrochemistry. Elsevier Science. ISBN 978-0-444-51958-0.
  4. ^ J.M. Seveant, E. Vianello (1965). "Potential-sweep chronoamperometry: Kinetic currents for first-order chemical reaction parallel to electron-transfer process (catalytic currents)". Electrochimica Acta. 10 (9): 905–920. doi:10.1016/0013-4686(65)80003-2.