Cyclic Voltammetry (CV)
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Cyclic voltammetry (CV) is a type of potentiodynamic electrochemical measurement. This popular method is generally used to study the electrochemical properties of an analyte in solution, electrochemistry of electroactive films on electrode surfaces, the course of polymerization, oxidation potential (e.g., from +0.25 to +0.65 V), electrochemical stability of the electrolytes on the electrodes in Li Batteries, biological samples such as biological fluids and tissue homogenates, and organic extraction.

In this technique, the electrochemical cell typically includes three electrodes: a working electrode (e.g. glassy carbon or mercury film electrodes with 3.3 mm in diameter, an electrode coated with a protein film), a reference electrode (e.g., Ag/AgCl), and an auxiliary (or called counter) electrode (e.g., platinum wire). The working electrode potential is ramped linearly versus time, at a constant scan rate v=ΔE/Δt (e.g., from 0.1 mV/s to a million or more volts per second). The potential ranges that is chosen to encompass the reduction and oxidation potentials of the electroactive species in films are normally in the voltage range between -1.5 and 1.5 V. After the set potential is reached, the working electrode's potential is ramped in the opposite direction to return to the initial potential. The potential in this technique sweeps back and forth between the two predefined potentials - either towards the positive potential to evaluate reducing equivalents or towards the negative potential to evaluate oxidizing species. These cycles of ramps in potential may be repeated as many times as desired. The current at the working electrode is plotted versus the applied voltage to give the cyclic voltammogram trace.

The cyclic voltammogram can present some characteristics such as:
i) A peak in the I versus E output denotes a flow of electrons between the protein in the film and the underlying electrode, leading to a change in the oxidation state of the protein's electroactive site.
ii) Electroactive species depleted by electrode reaction are replenished by diffusion from the solution bulk to the surface of the electrode prior to the electron transfer reaction.