What are the benefits of using a potentiostat in electrochemical experiments?

Most electrochemical experiments are performed using a potentiostat. What makes these devices so popular?

Devices that only allow very passively to observe a system, like a voltmeter, amperemeter, or multimeter, can only register voltage or current caused by chemistry over time. There is no control over the observed change.

• A potentiostat is nowadays usually a combination of a galvanostat, potentiostat, and impedance analyzers.
• A potentiostat controls the potential and measures the resulting current.
• A galvanostat controls the current and measures the resulting potential.
• An impedance analyzer applies a sine wave-shaped potential profile to the cell and calculates from the sine wave current response the impedance and phase shift of the cell.

This makes potentiostats more versatile and their active control of a parameter more powerful than regular meters.

There are also specialized potentiostats on the market, that are labeled according to their application, e.g. battery cyclers. So, you might have used a potentiostat without knowing.

Potentiostats often operate in a 3-electrode configuration, which allows for a current-free potential fix point, the reference electrode. This way the potential of the working electrode during the whole measurement is reliably known. Thus, an additional benefit is the precise control of the working electrode’s potential without the influence of concentration polarization at the counter electrode. This is the main feature that distinguish a potentiostat from a programmable power supply.