Potentiostat
From Wikipedia, the free encyclopedia
A potentiostat is a control and measuring device that, in an electrolytic cell, keeps the potential of the working electrode at a constant level with respect to the reference electrode. It consists of an electric circuit which controls the potential across the cell by sensing changes in its resistance, varying accordingly the current supplied to the system: a higher resistance will result in a decreased current, while a lower resistance will result in an increased current, in order to keep the voltage constant. It is a simple application of Ohm's law
As a result, the variable system resistance and the controlled current are inversely proportional
- Io is the output electrical current of the potentiostat
- Ec is the voltage that is kept constant
- Rv is the electrical resistance that varies
In a potentiostatic coulometry experiment, the cathode is usually a platinum electrode with a large surface area or a mercury pool, although other particularly reactive electrodes can be used in rare circumstances such as Lithium counter electrodes in Li-ion battery studies.
In impedance measurements, genarally a second equipment is attached to the potentiostat such as a function generator or frequency response analyzer. Some cases impedance measurement capability is built in to the potentiostat so that no need of a second equipment.
The functionality of a potentiostat can be extended by virtual instrumentation: in virtual instruments the potentiostat is used as an actuator.
[edit] See also
[edit] External links
- Genady Ragoisha (webmaster), "potentiodynamic electrochemical impedance spectroscopy (PDEIS)", Physico-Chemical Research Institute, Belarusian State University. A description of the use of a potentiostat in virtual instrumentation for electrochemical experiments.
- Pierre R. Roberge (Webmaster) "Potentiostat", corrosion-doctors.org Electrochemistry Dictionary.
