potentiostat

A potentiostat is an electronic instrument used in electrochemistry to control the voltage difference between a working electrode and a reference electrode while measuring the current that flows through the cell. In a typical three-electrode setup, a working electrode where the reaction occurs, a stable reference electrode, and a counter electrode complete the circuit. The potentiostat maintains the desired potential at the working electrode by sourcing or sinking current at the counter electrode, using feedback from the measured potential.

Operation modes: potentiostatic mode keeps the potential constant, galvanostatic mode maintains constant current, and both can be combined for various experiments. Common techniques performed with a potentiostat include cyclic voltammetry, chronoamperometry, chronopotentiometry, and impedance spectroscopy, often controlled by software. The current measured relates to the kinetics and mechanisms of the electrochemical reactions at the working electrode.

Applications: used in corrosion testing, battery and supercapacitor research, electroplating, electrochemical sensing, and fundamental electrochemical studies. Variants include benchtop and portable handheld units, and some integrate with frequency response analyzers for impedance measurements. Important considerations include uncompensated resistance, iR drop, electrode surface area, scan rate, and noise; many instruments offer automatic iR compensation and shielding.