The discovery of fullerenes, carbon nanotubes, and, more recently, the isolation of monolayer graphene sparked a revolution in the fabrication of a variety of carbon allotropes. Graphene can be viewed as the building block of several allotropes, e.g., carbon nanotubes, three-dimensional (3D) graphene-based nanostructures (GNSs) and devices that have been either fabricated or predicted theoretically for potential applications, even machines. Origami, the ancient art of paper folding, has been widely used in diverse areas, from architecture to battery design and DNA nanofabrication. It has also inspired the fabrication or simulation of macroscale origami graphene structures and devices, even machines. However, due to technical difficulties, atomically precise and controllable graphene origami for the creation of custom-design GNSs with quantum features has remained an open challenge. I this talk, I will present a demonstration that origami is an efficient way to convert graphene nano-fragments into complex nanostructures with atomic-scale precision. By scanning-tunneling-microscope manipulation, 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, while folding bicrystal GNIs creates well-defined intramolecular junctions (IMJs). These tubular edges are structurally similar to carbon nanotubes (CNTs) and corresponding IMJs. These results will set the stage for the discovery of new and unusual phenomena, as the folded GNIs are composite structures comprising a CNT-like fold and a twisted bilayer graphene. For example, it is worth exploring the superconductivity of the twisted bilayer graphene part with a magic twist angle attached to either a semiconducting or metallic tube or an IMJ.

* In collaboration with, Hui Chen^1,2_, Yi Pan^1,2_, Jinhai Mao^1,2_, Li Huang^1,2_, Xian-Li Zhang^1,2, Yu-Yang Zhang^2,1, Dongfei Wang^1,2, De-Liang Bao^1,2, Yande Que^1,2, Shixuan Du^1,2, Min Ouyang³, Sokrates T. Pantelides^2,4

¹ Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190, China. ² School of Physical Sciences, U. of Chinese Academy of Sciences, CAS, Beijing 100190, China. ³ Department of Physics, University, University of Maryland, College Park, MD 20742, USA. ⁴ Departments of Physics and Astronomy and Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA.

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