Proof of a Decades-Old Theory Hides in the Thinnest of Materials

Published in ACS Nano, a team of researchers based in the Department of Chemistry and the National Graphene Institute, have been able to fabricate a device with a diameter as small as 5 micrometres.

Using hexagonal boron nitride (hBN), sometimes known as white graphene, the study shows that, electrons could pass through the hBN acting as a barrier between a graphite electrode and suitable molecules (“redox couples”) in a liquid solution.

Ultramicroelectrodes are electrodes with characteristic dimensions on the micrometre or sub-micrometre scale. Due to their properties, they have pushed the boundaries of electrochemistry into small length scales.

In this case, the combination of the ultramicroelectrodes and tunnelling through atomically-flat hBN created perfect conditions to reveal peculiar discrepancies in the measured electrochemical properties. These discrepancies turned out to be direct manifestation of the Marcus-Hush theory of electron transfer, in a stunning agreement with unproven theoretical predictions.

Dr Matej Velicky said: “The moment of realisation that our experimental results are in a perfect match with an unverified theoretical prediction was exhilarating, and reminded us of the power and beauty of the scientific method”

Professor Robert Dryfe said:” The key to this experiment lies in the ability of to build up “designer” materials, by layering 2D materials on top of other materials in a highly controlled fashion. Such a unique experiment was only conceived because of the facilities and expertise of the National Graphene Institute.”

In addition, this research provides a novel experimental platform, which could be applied to address a number of scientific problems such as the identification of reaction mechanisms, surface modification, or long-range electron transfer, which are very important processes in chemical catalysis, sensing, and biology.

Link to the paper can be found below:
Electron Tunneling through Boron Nitride Confirms Marcus–Hush Theory Predictions for Ultramicroelectrodes

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