Lab Technique - Electrochemistry

Here's something really different for all of you out there. My internship focuses mainly on electrochemistry which is the study of chemical reactions involving the transfer of electrons between electrodes and electrolytes.

(Picture taken from http://www.als-japan.com/1031.html)

Electrodes come in different sizes and differ in the inert material in the middle. This picture shows a few glassy carbon electrodes. For a gold electrode, the middle will be gold instead of grey.

Electrodes are electrical conductors that can be used for various purposes such as electrocardiography (ECG) and chemical analysis using electrochemical methods. There are different types of electrodes available in the market but the ones that I have been using are the gold (Au) electrodes.

In order to ensure that the Au electrodes are fit for use, they are polished to remove unwanted chemical residues from previous use. New electrodes of course, do not need to be polished. Polishing is done using alumina powder on a nylon pad. The electrodes are held perpendicular to the nylon pad (with Au in contact with the pad that has alumina powder.) Then for a desired time (eg 10 min each), these electrodes are polished in a figure of 8 or circular motion. The particles in the alumina powder will remove the residues on the gold surface. In addition, nano-strip can be used too. By incubating the electrodes in nano-strip for 15 min, any remaining organic residues are removed.

So how do you know if the electrodes are clean? Electrochemical signals are measured with an electrochemical workstation. A clean Au electrode should give a high electrochemical signal while a Au electrode covered with residues will give a low signal because these residues will slow down the transfer of electrons between the electrode and electrolyte.

(Picture taken from http://www.uni-muenster.de/Physik.PI/DeCola/equipment.html)

This is a picture of an electrochemical workstation. The electrodes are connected to the workstation with the use of wires so that a small amount of voltage can be passed through.

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