voltammetrie

Voltammetry is an electrochemical method in which information about an analyte is obtained by measuring current as a function of an applied potential. In a voltammetric experiment, a potential is swept, stepped, or pulsed at the working electrode while the current that results from redox reactions at the electrode surface is recorded. The technique is usually performed in a three-electrode cell with a potentiostat: a working electrode, a stable reference electrode, and a counter electrode. The measured current reflects the rate of electron transfer between the electrode and the species in solution and is influenced by diffusion, adsorption, and kinetics.

Voltammetric data are presented as voltammograms, plots of current versus applied potential, where Faradaic currents corresponding to oxidation or reduction peaks are superimposed on a capacitive background. The peak potential provides information about the redox potential of the analyte, while the peak current relates to its concentration for diffusion-controlled processes, often described by simple electrochemical models. Non-Faradaic or background currents can complicate analysis and are mitigated by waveform optimization and data processing.

Several voltammetric techniques are widely used. Cyclic voltammetry involves sweeping the potential between two limits and reversing direction to study redox couples, reaction kinetics, and electrode surfaces. Linear sweep voltammetry applies a unidirectional ramp. Differential pulse voltammetry and square-wave voltammetry employ pulsed or alternating waveforms to enhance sensitivity and suppress background, enabling trace analysis. Modern implementations include miniaturized and in situ sensors using screen-printed or microelectrodes, expanding applications in environmental monitoring and biomedical diagnostics.

Applications of voltammetry span chemical analysis, corrosion studies, and battery or catalysis research, with uses in environmental monitoring, clinical testing, and material science. It offers relatively fast measurements and compatibility with diverse electrolytes, though accurate interpretation requires understanding of electrochemical mechanisms and potential interferents.