Growth of Graphene Nanoribbons and Carbon Onions from Polymer

Graphene nanoribbons and carbon onions are directly prepared by electron beam irradiation of polyacrylonitrile and expanded polystyrene nanofibers, respectively. By controlling the irradiation process in a high resolution transmission electron microscope, the number of layers of the graphene nanoribbons, as well as the dimension of the carbon onions, can be controlled. It is found that the initial diameter of the nanofiber has a strong effect on the final results. A mechanism is proposed to explain the transformation of polymer nanofibers to carbon nanostructures under electron beam irradiation. This supposes that the polymer nanofibers are first carbonized and then graphitized as a result of the high energy electrons. According to the mechanism, it is believed that all polymer nanofibers could be carbonized and then converted to graphene nanoribbons by proper electron beam irradiation.