Synthesis of Graphene Nanoribbons Encapsulated in Single-Walled Carbon Nanotubes

Abstract

A novel material, graphene nanoribbons encapsulated in single-walled carbon nanotubes (GNR@SWNT), was synthesized using confined polymerization and fusion of polycyclic aromatic hydrocarbon (PAH) molecules. Formation of the GNR is possible due to confinement effects provided by the one-dimensional space inside nanotubes, which helps to align coronene or perylene molecules edge to edge to achieve dimerization and oligomerization of the molecules into long nanoribbons. Almost 100% filling of SWNT with GNR is achieved while nanoribbon length is limited only by the length of the encapsulating nanotube. The PAH fusion reaction provides a very simple and easily scalable method to synthesize GNR@SWNT in macroscopic amounts. First-principle simulations indicate that encapsulation of the GNRs is energetically favorable and that the electronic structure of the encapsulated GNRs is the same as for the free-standing ones, pointing to possible applications of the GNR@SWNT structures in photonics and nanoelectronics.

Carbon Nanotubes as Electrically Active Nanoreactors for Multi-Step Inorganic Synthesis: Sequential Transformations of Molecules to Nanoclusters and Nanoclusters to Nanoribbons

“…This demonstrates a remarkable property of carbon nanotubes to act not only as nanoreactors constraining the space around the chemical reaction and templating the formation of nanoclusters or the growth of nanoribbons, but also as electrically active host-structures lending their electrons when they are required for a chemical reaction to occur inside SWNT, and retrieving electrons back when they are no longer required by the guest-species. In summary, carbon nanotubes are becoming an increasingly important class of nanoscale containers and reactors, where the pathways of chemical reactions can change significantly as a result of the restricted space of the reaction [5][6][7][8][9][10][11][12][13][14][15][16][17], or due to the interactions between the reactant molecules or catalyst particles with the host-nanotube [23,24]. Being highly conducting and having a symmetric distribution of filled and empty electronic states, SWNT possess remarkable electric properties and a unique ability to donate or accept electrons, which make nanotubes distinct among other nanocontainers and nanoreactors.…”

Chemical synthesis of graphene nanoribbons

“…On this basis, producing GNRs with tailor-made predefined widths, edge structure geometries and suitable solubility constitutes an important challenge for synthetic chemists. Bottom-up approaches reported to date include organic synthesis in solution via crosscoupling of the appropriate organic building-blocks followed by the dehydrogenation of the resulting oligomers, 37,38,[40][41][42][43][44][45][46][47] the conversion of precursors inside CNTs, 48,49 and surface-assisted polymerization with subsequent dehydrogenation in an ultra-high vacuum environment. 39,50,51 Although these bottom-up methods provide GNRs with a defined edge structure, they so far suffer from the inability to afford GNRs having variable widths at large scales, owing to the low solubility of the synthesized GNRs, and/or the need for highly-specialized instrumentation.…”

“…In 2011, Khlobystov and co-workers 48 reported an alternative method for the preparation of a sulfur-terminated graphene nanoribbon within a single-walled carbon nanotube (SWCNT). The basic idea for this strategy came from fullerenes, close relatives of GNRs, that can undergo chemical transformations inside SWNTs, triggered by heat or electron beam radiation (e-beam).…”

Electronic and Optical Properties of the Narrowest Armchair Graphene Nanoribbons Studied by Density Functional Methods

“…Consequently, several experimental techniques have been developed for synthesizing GNRs [10][11][12][13]. Because of their fascinating electronic, optical, and magnetic properties, GNRs have recently gained increasing interests .…”