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Materials made of nanometre-scale components have potential uses in a range of technologies, from batteries to aerospace. However, existing materials based on clay or carbon nanotubes have drawbacks. Striving to make use of an abundant and inexpensive starting material, Rod Ruoff of Northwestern University in Evanston, Illinois, and his colleagues found a way to transform graphite, allowing it to be split into individual sheets that can be stacked into a strong 'paper' (see page 457). Nature caught up with Ruoff to learn more about it.

Has graphite-based paper long been a goal?

For me, yes. No one has yet separated pieces of graphite into single layers on a large scale. Graphite is stiff in two of three dimensions, but has low overall strength because the individual crystals are only 'butted' against each other, not knitted together at their edges. Scientists and engineers would like to be able to separate and chemically manipulate individual graphite layers to make stiff, strong composites. Graphite also has other useful properties — for example, it is conductive.

What inspired this approach?

The abalone shell. This contains layers of mineral platelets held together by a protein 'glue'. I thought if we could disassemble graphite's layers and reassemble them similarly to this shell, we might get good stiffness but also high strength.

What was the key step?

The convertion of graphite to graphite oxide. This maintained the layered structure but altered the layers' carbon skeletons to be hydrophilic and so disperse well in water, yielding individual sheets of graphene oxide.

How does your method interlock the sheets?

We aren't sure. This is still discovery-based science. Further experiments are needed to determine the process of layer building, and we hope that they might also lead to better control of the stacking.

What is the biggest challenge for designing nanomaterials?

An exciting challenge is to achieve control from the atomic through to the macro scale so that we know the location of every atom. Then, we could 'dial in' a much wider range of useful properties.

Where might this material be used?

In aerospace and in anything needing strong, lightweight materials. We think there are exciting opportunities in energy storage, such as in batteries and supercapacitors. It might even be used in structural components of windmill turbine blades.