Achieving edge-closed graphene nanoribbons by squashing carbon nanotubes

Long, constrictive graphene nanoribbons (GNRs) with creaseless edges, sizable bandgap and precocious mobility are highly desirable for physics and optoelectronic applications. However, efficiently preparing specified GNRs is difficult. Recently, Changxin Chen and his colleagues study that sub-10-nm-wide semiconducting graphene nanoribbons with atomically creaseless closed edges tin beryllium produced by squashing c nanotubes utilizing a high-pressure and thermal treatment. The survey was published online September 6 successful Nature Electronics.

One large obstacle to the exertion of graphene successful electronics and optoelectronics has been that two-dimensional graphene is simply a semimetal with the zero bandgap. One solution is to usage one-dimensional graphene nanoribbons (GNRs) with a constrictive width. Previous studies had demonstrated that the GNRs with a width of

On the different hand, it is inactive a ample situation to get the 100% semiconducting single-walled c nanotubes (SWCNTs) based connected contiguous separation oregon maturation exertion of CNTs. "This besides grants constrictive GNRs a cardinal vantage implicit SWCNTs successful producing all-semiconducting devices for the exertion successful aboriginal integrated circuits," said Changxin Chen, the archetypal writer and corresponding writer of this enactment and a prof of physics subject and exertion astatine Shanghai Jiao Tong University. 

Unfortunately, precocious prime GNRs that are ultra-narrow and agelong are hard to synthesize—particularly ones with creaseless edges passim the ribbon length. Thus, a method to efficiently nutrient constrictive and agelong GNRs with atomically creaseless edges is an urgent absorption of the probe community.

In the work, a diamond anvil compartment (DAC) was utilized for the high-pressure attraction of CNTs. The CNT samples were loaded and sealed successful a illustration enclosure successful the centre of a pre-indented tungsten gasket that was past compressed betwixt 2 diamond anvils. Figure 1 illustrates the structural alteration successful CNTs earlier and aft the high-pressure and thermal treatment, wherever the pristine CNTs are squashed into GNRs aft treatment. The exertion of a precocious non-hydrostatic unit and suitable thermal attraction on with the stabilizing effect of innate defects successful CNTs lend to the realization of irreversible radial deformation for CNTs. This makes CNTs beryllium squashed into GNRs. The GNRs obtained from squashed CNTs person atomically smooth, closed edges and fewer defects.

With this approach, GNRs narrower than 5 nm were obtained, and a GNR width down to 1.4 nm was recorded, which is the 1 of the narrowest among GNRs fabricated utilizing top-down approaches reported to date. Edge-opened GNRs could besides beryllium prepared via utilizing an oxidant, HNO3, to selectively etch the edges of the squashed CNTs nether precocious pressure. A precocious output up to 54% could beryllium achieved to squash single-walled and double-walled CNTs into edge-closed GNRs. A emblematic field-effect transistor (FET) constructed by a 2.8-nm-wide edge-closed GNR exhibits a precocious broad show with precocious Ion/Ioff ratio (>10^4), on-state conductivity (7.42 mS) and instrumentality mobility (2,443 cm^2 V^−1 s^−1) achieved concurrently. And a bandgap of ~494 meV is estimated for this GNR. High-yield synthesis of constrictive semiconducting GNRs with high mobility and sizable bandgap is important for its large-scale instrumentality integration.

The method successful this enactment supply a way to nutrient high-quality, narrow, and agelong semiconducting GNRs and to power the GNR's borderline types for exploring their cardinal properties and applicable applications successful electronics and optoelectronics. It is simply a important beforehand successful the accumulation of high-quality GNRs and high-performance GNRFETs. "Comparing with the methods reported earlier, this caller attack is susceptible of producing overmuch narrower GNRs," Changxin Chen said. "Moreover, the atomically creaseless edges passim the full GNR tin beryllium achieved by our method, resulting successful precocious worldly and instrumentality mobility."

"Taking vantage of our method's precocious yield, it is hopeful to standard up the synthesis by further utilizing a multi-anvil apparatus oregon a large-volume press. Importantly, this method tin besides beryllium extended to marque different material-based nanoribbons from squashed nanotubes and to flatten different fullerene materials," said Changxin Chen.

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Provided by Shanghai Jiao Tong University