AsianScientist (Oct. 1, 2019) – In a study published in the journal Science, researchers in China have found a way to fold single layers of graphene precisely, unlocking novel electronic and magnetic properties of the material.
The potential to fold graphite into precise nanostructures using a scanning tunneling microscope (STM) has teased researchers ever since the mid-1990s. However, ensuing studies by various research groups around the world could not command where or how the folds would occur.
Now, by replacing the graphite with high-quality graphene nanoislands, researchers in China and the US have leveraged the atomic-level control of STM to create an origami nanofabrication tool.
To produce well controlled single-atom thick nanoislands, the researchers bombarded highly oriented pyrolytic graphite with hydrogen ions for ten cycles before annealing them. The whole procedure takes around ten hours in a vacuum. Starting from a single graphene layer, the team created different origami nanostructures by modifying the atomic layer itself. They were able to generate various configurations of the material, such as a bicrystal graphene island.
“Similar to conventional paper origami, our current work has made it possible to create new complex nanostructures by custom-design folding of atomic layer materials,” said Professor Gao Hong-Jun at the Chinese Academy of Sciences (CAS) who led the research in collaboration with colleagues at Vanderbilt University and the University of Maryland in the US.
The team reported that they can now fold single layers of graphene with the direction of the fold specified over a range of 1.1-60°, with a precision of 0.1°. Their STM manipulations also leave tubular structures at the edges with characteristics similar to carbon nanotubes.
“We have demonstrated that through such simple graphene origami we can realize various graphene structures like carbon nanotubes and their intramolecular junctions,” he said.
Going forward, Gao and colleagues hope to extend their demonstration of the technique to other two-dimensional materials such as molybdenum disulfide and hexagonal boron nitride. Such research could result in the development of better superconductors and ferromagnets, as well as facilitate discoveries in quantum field theory.
The article can be found at: Chen et al. (2019) Atomically Precise, Custom-design Origami Graphene Nanostructures.
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Source: Chinese Aademy of Sciences.
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