Potentiostatic

Potentiostatic refers to a mode of electrochemical control in which the potential of a working electrode is held constant with respect to a reference electrode. In this mode, the current is free to respond to the electrochemical processes at the electrode surface and is recorded as a function of time or applied potential.

Potentiostatic control is implemented with a potentiostat in a three-electrode cell: a working electrode where the reaction occurs, a reference electrode that defines the potential, and a counter (or auxiliary) electrode that supplies current. The instrument measures the set potential and uses a feedback loop to adjust the current at the counter electrode to maintain the chosen potential. In this arrangement, the measured current reflects the kinetics and mechanisms of the electrode reaction under the specified potential.

Applications of potentiostatic control include electrodeposition or electroplating at fixed potential to influence deposit properties, corrosion studies through polarization experiments, and fundamental electrochemical research such as chronoamperometry and chronopotentiometry. Potentiostatic experiments help analyze reaction kinetics, diffusion effects, and polarization behavior by examining how current responds to controlled potentials.

Potentiostatic methods are contrasted with galvanostatic methods, where the current is held constant and the potential is free to vary. Potentials are defined relative to a reference electrode, typically Ag/AgCl, SCE, or calomel. Potentiostatic control is widely used in materials science, electrochemistry, and corrosion engineering to study deposition, corrosion rates in real-time, and the behavior of battery and supercapacitor electrodes.