Potentiostat for Cyclic Voltammetry

Potentiostats are electronic control and measurement instruments designed for use with a three electrode cell. They output a controlled potential by using feedback circuitry to counteract the redox events taking place in the electrochemical reaction of a material.

How do Potentiostats Work?

Potentiostats are able to maintain a constant measured potential by using feedback circuitry between the output and measured potential to respond to changes in the resistance of the circuit (or electrochemical cell).

Potentiostatic experiements use a three electrode system consisting of a working electrode, a counter electrode and a reference electrode.

The potential of the reference electrode remains fixed while the potentiostat varies the potential of the working electrode. The counter electrode completes the circuit and allows current to flow, counteracting the redox events taking place at the working electrode and ensuring that no current passes between the reference and working electrodes.

Why use a Three Electrode System?

Unlike in a two electrode system, using separate counter and reference electrodes allows you to control the potential between the working and reference probes while measuring the current between the working and counter probes. This makes electrochemical methods like cyclic voltammetry possible.

How does Cyclic Voltammetry Work?

In cyclic voltammetry, a linearly ramping potential is applied between the working and reference electrodes. This potential is cycled such that the ramp is applied in one direction, then in reverse, forming a triangular wave. Whilst this is occurring, the electrical current is measured between the working and counter electrodes.

Computer software allows the maximum and minimum potentials to be defined as well the number of cycles, the scan rate, and the current range.

The Ossila Potentiostat produces the resulting plot, known as a cyclic voltammogram, in real-time as the experiment is being run. The data can then be saved in a .CSV file for further analysis in any analytical tool.

For more information on, please refer to our extensive cyclic voltammetry guide. This covers the underlying theory of potentiometry and voltammetry and explains the experimental set up in more depth than is covered here.

What Does Cyclic Voltammetry Measure?

Cyclic voltammetry can be used to determine various electrochemical properties. These include the redox potentials, the reversibility of a reaction, electron transfer kinetics and the energy levels of semiconducting materials, i.e. polymers or small molecules.

Specifications

Pricing and Options

The complete three electrode system comes with three electrodes and a high quality cell, included at a reduced price for purchasers of the Ossila Potentiostat. A lower price option is also available if you wish to buy the potentiostat without a cell. Both packages qualify for FREE worldwide shipping and our two-year equipment warranty.

The Ossila Potentiostat comes with control and measurement software for performing cyclic voltammetry. Software updates are also provided at no extra charge and are available to download from our website.

As with all of our software, data is saved to comma-separated value (.csv) files so that you can analyse it with your favourite tool. The settings you define are saved alongside your measurement data so that you always have a record of your experimental parameters.

Profiles allow you to save commonly used settings configurations so that you can quickly repeat measurements without re-configuring the potentiostat, further speeding up your research. 

Software Key Features

Our intuitive potentiostat software enables you to easily perform cyclic voltammetry. Simply set the current range, start potential, potentials at which the scan changes direction, scan rate, and number of cycles and click 'Measure'. Watch the measurement as it happens with live plotting of data.

Software Requirements

Software Installation

To install the cyclic voltammetry PC software, download the latest version from our website or insert the supplied USB memory stick into your computer and run the ‘Ossila-Cyclic-Voltammetry-Installer-vX-X-X-X’ file.

On Windows 10, the necessary drivers are installed automatically when you first connect the Potentiostat to your computer. If you are using an older version of Windows you can find both 32-bit and 64-bit drivers either on the software download page or in the ‘SMU-Driver’ folder on the memory stick.

Please refer to the Potentiostat product manual for more information.

The Ossila Potentiostat has been designed to make it quick and easy to perform cyclic voltammetry. Purchase the complete package to enjoy a significant discount on the cell and electrodes (compared to when bought separately) and get everything you need to set up a three electrode system and start taking measurements.

Experimental Set Up for Cyclic Voltammetry

The experimental set up for cyclic voltammetry comprises a potentiostat connected to a three electrode electrochemical cell. To set up a three electrode system for cyclic voltammetry, fill the cell with an electrolyte solution and place the electrodes within.

This can then be connected to the sockets on the front of the Ossila Potentiostat using the supplied cable and crocodile clips. The red socket connects to the working electrode, the black socket connects to the counter electrode, and the blue socket connects to the reference electrode.

How to Perform Cyclic Voltammetry with the Ossila Potentiostat

Once you have set up your three electrode electrochemical cell and connected it to the potentiostat, performing Cyclic Voltammetry takes only a few clicks.

The potentiostat will be detected automatically on starting the Ossila Cyclic Voltammetry PC software, and from here the current range, potentials, scan rate and number of cycles can all be specified.

When you are ready to start the scan, click “Measure” and watch in real time as the test is performed and a cyclic voltammogram is generated.

The system will sweep the potential between the working electrode and reference electrode while measuring the current between the working electrode and counter electrode. This will be repeated for the specified number of cycles. If ‘Save After Measurement’ is turned on, the measurement data and settings will be saved as CSV file once the sweep has finished.

Cyclic Voltammetry of Ferrocene

Ferrocene (Fc) is used as the standard reference for cyclic voltammetry.

Before you start, ensure that all apparatus, solvents and electrolytes are completely dry. The presence of any water and its redox by-products may reduce the solvent potential window or react with the solvent or analyte. The cell and electrodes should always be thoroughly rinsed immediately after each experiment with the solvent that was used in your electrolyte.

We also recommend switching on the potentiostat 30 minutes prior to use. This will allow it to warm up and reach a stable temperature, which will help to ensure a stable measurement.

How to Prepare an Electrolyte Solution

The first step when preparing an electrolyte solution is to choose which solvent and electrolyte you are going to use given the solvent potential window and the solubility of your analyte. Note that most electrolytes are hygroscopic, so should be stored in a desiccator or inert atmosphere.

For this example we are going to use a 0.1 M solution of tetraethylammonium hexafluorophosphate (TEAPF6) in acetonitrile as our background electrolyte, but other electrolyte salts and solvents could be used instead.

In order to make up 20 ml of 0.1 M solution, weigh out 0.550 g of dry tetraethylammonium hexafluorophosphate (275.2 g/mol) into a dry volumetric flask. Add acetonitrile up to mark of the volumetric flask and stir until the electrolyte has dissolved.

Secure the electrochemical cell with a clamp to ensure it is stable before adding the 20 ml of electrolyte solution. Once dissolved, add approximately 10 mg of Fc to the solution and stir to dissolve it.

Setting up the Electrochemical Cell

With the electrolyte solution prepared, the electrochemical cell is nearly ready. Place the cap on the electrochemical cell and insert the working and counter electrodes into two of the holes.

You can now prepare the reference solution, in this case a 0.01 M solution of silver nitrite in acetonitrile. Prepare the solution in a volumetric flask and add it into the reference electrode tube with a syringe and needle until the tube is approximately 2/3 full.

Insert the reference electrode into the final hole in the cap. To remove dissolved oxygen, gently bubble inert gas through the solution using a thin tube or needle for approximately 10 minutes.

Taking a Measurement

Once the electrochemical is set up, use banana cables to connect it to the correct ports on the front of the Ossila Potentiostat and start the cyclic voltammetry software. The potentiostat will be detected automatically.

Various measurement settings can now be set.

• Choose the appropriate current range for the material being measured. Fc will give a signal in the tens to hundreds of microamps, so the 200 μA range is suitable.
• Fc undergoes a reversible single electron transfer between 0 and 0.2 V (versus Ag/AgNO3) so set the 'Start Potential' and 'Potential Vertex 2' fields to -0.4 V and the 'Potential Vertex 1' field to 0.5 V.
• The scan rate will affect the magnitude of the current peaks in the scan, with faster scan rates resulting in greater measured currents. In this measurement we will use a scan rate of 100 mV/s.
• The number of cycles is how many times the measurement will be performed, and typically is set to 1.

When you are ready to start taking the measurement, withdraw the tubing or needle used to degas the cell until it is no longer in the solution and click the “Measure” button.

The plots below show voltammograms taken for different molar concentrations of ferrocene (10^-2 M, 10^-4 M and 10^-6 M. At the higher concentrations, the anodic and cathodic current peaks are clearly visible, while at 10^-6 M the concentration is too low to allow the peaks to be seen. 

Maintenance

The cell and electrodes should always be thoroughly rinsed immediately after each experiment with the solvent that was used in your electrolyte. Always set the cell to dry, preferably in an oven, before you prepare your electrolyte. This helps reduce contamination of your solution from water.