Science | 2019
Atomically precise, custom-design origami graphene nanostructures
Abstract
Precisely folding nanographene Graphene nanostructures that would result from folding or rolling graphene monolayers or bilayers have been predicted to have a number of interesting electronic properties, but control over such folding processes has been limited. Chen et al. used a scanning tunneling microscope tip to fold and unfold graphene nanoislands etched on graphite surfaces at low temperatures (4 kelvin). The fold angle could be precisely controlled to create different twist angles in bilayer graphene and a tubelike edge in folded graphene. They also folded 5 ring–7 ring defects and explored this heterojunction with scanning tunneling spectroscopy. Science, this issue p. 1036 A scanning tunneling microscope tip can fold and roll graphene nanosheets along predetermined directions. The construction of atomically precise carbon nanostructures holds promise for developing materials for scientific study and nanotechnology applications. Here, we show that graphene origami is an efficient way to convert graphene into atomically precise, complex nanostructures. By scanning tunneling microscope manipulation at low temperature, we repeatedly fold and unfold graphene nanoislands (GNIs) along an arbitrarily chosen direction. A bilayer graphene stack featuring a tunable twist angle and a tubular edge connection between the layers is formed. Folding single-crystal GNIs creates tubular edges with specified chirality and one-dimensional electronic features similar to those of carbon nanotubes, whereas folding bicrystal GNIs creates well-defined intramolecular junctions. Both origami structural models and electronic band structures are computed to complement analysis of the experimental results. The present atomically precise graphene origami provides a platform for constructing carbon nanostructures with engineered quantum properties and, ultimately, quantum machines.