Nanotomy-based production of transferable and dispersible graphene nanostructures of controlled shape and size

TLDR

Graphene nanostructure properties depend on shape and size, yet existing synthesis methods fail to produce large, transferable, shape‑controlled structures across a wide size range, resulting in low yields. The study aims to produce graphene nanostructures of predetermined shapes and controlled dimensions. This is achieved by diamond‑edge nanotomy of graphite into nanoblocks followed by exfoliation, yielding monodisperse shapes. The resulting nanostructures have straight, smooth edges (ID/IG 0.22–0.28, roughness < 1 nm) and GN‑ribbon films exhibit a width‑dependent bandgap that rises from 0 meV at 50 nm to ~35 meV at 15 nm.

Abstract

Because of the edge states and quantum confinement, the shape and size of graphene nanostructures dictate their electrical, optical, magnetic and chemical properties. The current synthesis methods for graphene nanostructures do not produce large quantities of graphene nanostructures that are easily transferable to different substrates/solvents, do not produce graphene nanostructures of different and controlled shapes, or do not allow control of GN dimensions over a wide range (up to 100 nm). Here we report the production of graphene nanostructures with predetermined shapes (square, rectangle, triangle and ribbon) and controlled dimensions. This is achieved by diamond-edge-induced nanotomy (nanoscale-cutting) of graphite into graphite nanoblocks, which are then exfoliated. Our results show that the edges of the produced graphene nanostructures are straight and relatively smooth with an ID/IG of 0.22–0.28 and roughness <1 nm. Further, thin films of GN-ribbons exhibit a bandgap evolution with width reduction (0, 10 and ~35 meV for 50, 25 and 15 nm, respectively). Current top-down and bottom-up syntheses of graphene nanostructures suffer from low yields or do not produce structures with different and controlled shapes. Here, monodisperse graphene shapes are produced by diamond-edge cutting of pyrolytic graphite followed by exfoliation.