What are the different types of potentiostats and their applications?

Electrochemistry is a broad field with many different applications. This is reflected in the electrochemical instruments as well. Potentiostats, Galvanostats, and Impedance Analyzers are rather versatile but often have a focus on certain properties added with an application in mind.

Many researcher instruments are actually a combination of potentiostats, galavanostats, and impedance analyzers. Often people will call these combinations just potentiostats and not potentiostat/galvanostat.

There are many different applications for electrochemical instruments.

1

Energy conversion applications

Batteries, supercapacitors, fuel cells, solar cells, hydrogen evolution, and other energy conversion applications are developed to store more charge, have higher power, etc. As a result, a common request is currents of 1 A or higher and voltages of more than 6 V. However, there are also button cells, bio-fuel cells, and similar low-power energy devices where 100 µA is a sufficient current.

2

Corrosion research

Corrosion research is a very broad field. The demands vary from measuring currents in the nA range up to A. The main influences on the current are the samples’ surface area, the material of the sample, and the presence of coatings. Dental implants would require very low currents while characterizing new alloys can lead to rather high currents. In the field of corrosion research, measurements often take place outside the lab. Pipelines or buildings need to be investigated on-site. This means there are many accessories for corrosion researchers, which allow them to perform electrochemistry on cylindrical, flat objects or sections of very large samples.

Additionally, corrosion research often requires a lot of processing of raw data. For example, following the polarization resistance over time requires for each measurement point a small linear sweep voltammetry (LSV) also known as linear polarization (LP) across around 20 mV, followed by a linear fit, and then 1 divided by the slope is the polarization resistance. Accordingly, software with automated data processing is popular in the field of corrosion research.

 

3

Electroanalysis

Electroanalysis answers the question of what the concentration of a certain substance is, or in simpler cases, if the substance is present or not. Electroanalysis requires often accurate measurements of current in the µA range and below. Many of the applications benefit from on-site measurements as well. For example, measuring the water quality next to a well allows immediate action if the water isn’t safe to drink. Potentiostats made for electroanalysis show a high accuracy at low currents and are portable.

These are just three groups for electrochemical applications, but there are more to explore, such as electrocatalysis, electrodeposition and photoelectrochemistry.

Different types of potentiostats

Due to electrochemistry’s wide range of applications, there are different types of potentiostats.

  • Most of the time people will use single-channel potentiostats. These devices are made to work in a single cell.
  • Bipotentiostats or Bipots in short offer a second working electrode that shares the same reference and counter electrode as the first working electrode. These potentiostats are handy to compare two different electrodes in the same cell, for example a selective probe and a blank. They are also handy For Rotating Ring Disc Electrodes (RRDE), where a ring-shaped and a disc-shaped electrode need to be controlled simultaneously in the same cell.
  • The number of working electrodes can be even more. A device with multiple working electrodes and just one reference and one counter electrode is a polypotentiostat.
  • A more powerful option for multiple electrodes are multi-channel potentiostats. These instruments host multiple potentiostats in one housing. They can be operated at the same time or at independent times. The channels can perform the same or different techniques, because each channel is a potentiostat. There are also multi-channel potentiostats that can be used as polypotentiostats, i.e. multiple working electrodes sharing one counter and one reference electrode. We have a detailed application note about this topic.
  • The demand for on-site measurements lead to the development of portable potentiostats. PalmSens offers potentiostats with battery power and Bluetooth connection in a compact design, which are ideal for Electroanalysis. The broad range of currents combined with our user-friendly software make the potentiostat attractive for corrosion research. While in energy conversions we also offer potentiostats that can provide currents up to 200 mA.