Credit: © 2008 Wiley

Several methods have been developed for fabricating graphene structures, including the cleavage of layers from bulk graphite, epitaxial growth by chemical vapour deposition and thermal decomposition of silicon carbide. There is still a need, however, for techniques that can offer greater control over the number of layers and width of the graphene produced. A method has now been reported for turning nanofibres of poly(methyl methacrylate) into graphene nanoribbons, which can be fine-tuned to manipulate these properties.

In a one-step process, Erqing Xie and co-workers1 at Lanzhou University and the Chinese Academy of Sciences irradiated the poly(methyl methacrylate) fibres with an electron beam for two minutes. Over this time, the diameter of the fibre decreased and gradually formed a perfectly graphitized nanoribbon in which the layers were regularly spaced and were aligned with the incident electron beam. The macromolecular chains of the fibres are thought to be scissored by the electron beam, and the oxygen and hydrogen atoms lost as vapour, leaving just carbon atoms.

The number and width of the graphene layers could be fine-tuned by varying the irradiation time. The smallest ribbon formed was four graphene sheets thick but Xie and colleagues claim that a single sheet could be obtained.