Lancaster chemistry researchers are part of an international team of scientists that have discovered how to create tiny nanocorral structures - empty spots on an otherwise crowded surface - on graphite or sheets of graphene.

The discovery is important for several reasons: the nanocorrals can be used like microscopic petri dishes, enabling large numbers of experiments to be conducted in isolation all on the same piece of graphite or sheet of graphene. Also, chemical modification of graphene has a strong effect on its electronic properties. Controlled nanopatterning may therefore be useful for bandgap engineering and could have a major impact on the use of graphene in electronic devices.

The size of the nanocorrals can be varied from around 45 nanometres wide, which is around 2,000 times smaller than the width of a human hair, to around 130 nanometres. This minute size is beneficial to researchers because such a small confinement may increase the rate of reactions – as molecules will have a much higher chance of meeting each other.

Dr Stijn Mertens, Senior Lecturer in Electrochemical Surface Science and co-author of the research, said: “We have created a simple way to nanostructure a graphite surface, creating a matrix of disc-shaped open areas called nanocorrals. The pattern of the nanocorrals reminded us of so-called fairy circles, circular barren patches in grasslands that are particularly common in the Namibian desert.

“The empty areas of the nanocorrals can be very useful for researchers because they can study surface reaction in individual corrals that are all independent from each other. This means they can give statistically relevant results from reactions in each of them within a single experiment. Only very few other methods to make such nanopatterns are currently available, and they are much more complex. Our method is very straightforward, does not require special equipment, and leads to millions of uniform nanocorrals in a matter of minutes.”

The nanocorrals are created by electrochemically activating mixtures of aryl diazonium compounds, which researchers think creates nanobubbles close to the graphite surface – leading to the structure of the nanocorrals.

The research, which was led by researchers from KU Leuven in Belgium and also involves researchers from Quy Nhon University, in Vietnam, is outlined in the paper ‘Graphite and Graphene Fairy Circles: A Bottom-up Approach for the Formation of Nanocorrals’, which has been published by the journal ACS Nano.