Faculty of Physics

2D Materials

In Prof. Marika Schleberger’s research group, ‘2D materials’ were a high priority. These ultra-thin layers present an attractive field of research because many 2D materials display completely different material properties than the regular ‘thick’ version. This includes optical and electronic, but also mechanical, properties. A key point of the research activities of Schleberger’s research group still involves working on graphene, the best-known 2D material, which is made up of a single layer of carbon atoms. Recently a range of work, including part of the DFG project NUTEGRAM (a cooperation between several international groups) showed that with the help of a special ion ray for the correct selection of parameters, highly targeted nanopores can be created in well-defined sizes in free-standing graphene layers. These types of porous graphene layers have been suggested as the ideal ‘nanofilter’ for the smallest parts, e.g. viruses, because they have the correct hole size (high selectivity), but at the same time, would not lose friction due to the extremely low thickness (high permeability).

To build a nanofilter, you cannot simply refer back to free-standing graphene as it is too weak, despite its many quoted extraordinary properties, which means the filter would easily break under mechanical load. But even this problem has been solved: we have succeeded in manufacturing special graphene plastic films and then showing that the ion ray when passing through these hybrid slides leaves these types of nanopores not only in graphene, but also (in slightly different form) in the underlying plastic films. The great thing about it is that the pores in the plastic can be enlarged as desired after radiation by a chemical etching treatment without the graphene pores being affected! The graphene can also act as a nanofilter after etching, but is currently sustained by a rough, porous, stable plastic carrier film that hardly affects the flow of the mixture to be separated. Whether and how these nanofilters actually meet their requirements is to be part of the next investigation.