How does a potentiostat / galvanostat work?

A basic potentiostat uses a three electrode system (2 or 4 electrode connections are also possible). It measures and controls the voltage difference between a working electrode and a reference electrode which has a constant potential. It measures the current flow between the working electrode and counter electrode (that completes the cell circuit). As a galvanostat, the instrument controls the cell current rather than the cell voltage.

The working electrode could be a metal on which a reaction takes place or – in corrosion measurements – a sample of the corroded material. For testing batteries, the potentiostat is connected directly to the battery electrodes.

Electrochemical Impedance Spectroscopy (EIS) experiments allow the user to determine charge transfer resistance, double layer capacitance and ohmic resistance.

Why use a potentiostat / galvanostat / EIS?

A potentiostat is vital for the study of reaction mechanisms in electrochemistry, e.g. redox chemistry. Another use is the testing of batteries. Potentiostats can also be used to test for electrochemically active compounds (e.g. drugs, toxins) and microbes in solution.

Electrochemical Impedance Spectroscopy (EIS) has many applications. It can be used to study corrosion, e.g. in reinforced concrete, but also in electrode kinetics, double-layer studies, batteries, solid-state electrochemistry, and photovoltaic systems.

Our potentiostat / galvanostat / EIS systems

Crucial to the function of a potentiostat / galvanostat and applications like electrochemical impedance spectroscopy is the software. All our BioLogic instruments are controlled by the very versatile EC-Lab® software, to provide a range of measurement modes, with different modular techniques with wait and loop options to create complex experimental chain. This software is also able to control several potentiostats from a single interface view.

A wide range of quality indicators will help users to validate their EIS experiments, with regard to linearity, non-stationarity or noise.

Finally, in contrast to many other systems, it is possible to ‘Modify on the fly’, i.e. change parameter settings during an experiment when results are not as expected.

Examples of applications of potentiostats / galvanostats / EIS

Metallic surfaces can corrode while in contact with a corrosive solution (mostly acidic media). By using electrochemical methods you can study the behavior of the metal while submersed in a corrosive solution. Potentiostats / galvanostats are used to characterize the behavior of these metals. Techniques like, e.g., Electrochemical Impedance Spectroscopy (EIS), Linear Polarization Resistance and Tafel Plot experiments are used to characterize the behavior of the metals.

Photovoltaic cells are everywhere these days. Solar energy is important in local, regional and national energy production. To improve the efficiency of such an energy supply, a lot of research is done. Photovoltaic solar cells characterization can be performed by polarization and Electrochemical Impedance Spectroscopy techniques, which allow the user to determine cell performance and model. The contribution of the electrochemistry in energy fields is currently a hot topic.

Understanding the kinetics and the thermodynamics of a reaction occurring on an electrode is the general purpose of fundamental electrochemistry. Potentiostats / galvanostats and EIS are essential tools in this field. In this application, DC steady-state methods have been used such as: cyclic voltammetry, chronoamperometry, chronocoulometry, chronopotentiometry, pulse voltammetry, square wave voltammetry and other current-potential techniques.