Entirely new growth mechanism allows spontaneous folding growth of graphene

(Nanowerk News) A piece of paper folded over several times is able to carry more weight than a flat sheet of paper of the same length. Similarly, folding can also enhance the mechanical properties of graphene. Furthermore, the concepts of graphene origami and kirigami have inspired the design of quasi-three-dimensional graphene structures, which possess intriguing mechanical, electronic, and optical properties.
In Nano Letters ("Spontaneous Folding Growth of Graphene on h-BN"), researchers now report the use of a simple chemical vapor deposition (CVD) method to demonstrate that high-quality edge-folded bilayer graphene can be spontaneously grown on a h-BN substrate.
The researchers grew graphene on h-BN flakes, which were cleaved onto SiO2/Si substrate in advance. Subsequently, acetylene (C2H2) was introduced to our CVD system as the carbon feedstock with silane (SiH4) acting as a gaseous catalyst. The growth temperature was maintained at 1300 °C during the whole growth period.
Characterization of edge-folded bilayer graphene
Characterization of edge-folded bilayer graphene (EFBG). (a) Representative SEM image of the epitaxial monolayer graphene (blue circles) and EFBG (red circle) on the h-BN substrate. Inset shows the AFM friction image of the moiré pattern for a graphene/h-BN heterostructure with a period of ∼14 nm. (b) Representative AFM image of the folded edge and the corresponding height line profile. (c) Schematic of monolayer graphene and EFBG on h-BN. (Reprinted with permission by American Chemical Society) (click on image to enlarge)
Specifically, this method produces hexagram bilayer graphene containing entirely sealed edges in a controllable manner.
The spontaneous folding growth mode demonstrated in this work proposes a potential roadmap to achieve designed quasi-3D graphene microstructures by a simple CVD method. This novel approach allows an easier, more controllable means of folding graphene comparing with other mechanical/chemical methods.
Moreover, the tunable, elaborate hexagram constructions offer ideal platforms for studying the newly emerging physical properties involved in folded edges and topological defect lines.
Importantly, this innovative growth mode broadens our prospective horizon for the design of special 3D structures with 2D materials.
By Michael is author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: The Future is Tiny, and
Nanoengineering: The Skills and Tools Making Technology Invisible
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