Facile preparation of large-scale graphene nanoscrolls from graphene oxide sheets by cold quenching in liquid nitrogen

Graphene nanoscrolls (GNSs) are receiving intense interest because they are expected to possess some peculiar properties quite distinct from both graphene and carbon nanotubes. Research on GNS, however, has been hindered by limitations of the available preparation methods. Here we demonstrate a novel strategy for the large-scale preparation of GNSs from graphene oxide (GO) sheets by cold quenching, freeze-drying and subsequent thermal reduction. When a plastic box with a heated GO aqueous suspension is immersed in liquid nitrogen, GO sheets are able to roll up and most GNSs have diameters ranging from 200 to 600 nm. More interestingly, these GNSs connect each other to form a 3D network. The structural conversion is closely correlated with the initial temperature of GO suspension, the size of GO sheets and the immersion way. The liquid nitrogen cold quenching is a simple and controllable method for large-scale preparation of GNSs. The liquid nitrogen cold quenching is a simple and controllable method for large-scale preparation of GNSs.