Well-defined sub-nanometer graphene ribbons synthesized inside carbon nanotubes

TL;DR

This paper reports the synthesis and detailed characterization of well-defined sub-nanometer graphene nanoribbons inside carbon nanotubes, demonstrating a scalable method for their controlled growth with potential applications in nanoelectronics.

Contribution

The study introduces a novel high-temperature vacuum annealing technique to synthesize sub-nanometer graphene nanoribbons inside carbon nanotubes, with detailed structural and electronic characterization.

Findings

Successfully synthesized 6- and 7-armchair graphene nanoribbons with widths of 0.61 and 0.74 nm.

Determined excitonic gaps of 1.83 and 2.18 eV for the nanoribbons.

Confirmed the nanoribbons' structure via atomic resolution electron microscopy and Raman spectroscopy.

Abstract

Graphene nanoribbons with sub-nanometer widths are extremely interesting for nanoscale electronics and devices as they combine the unusual transport properties of graphene with the opening of a band gap due to quantum confinement in the lateral dimension. Strong research efforts are presently paid to grow such nanoribbons. Here we show the synthesis of 6- and 7-armchair graphene nanoribbons, with widths of 0.61 and 0.74 nm, and excitonic gaps of 1.83 and 2.18 eV, by high-temperature vacuum annealing of ferrocene molecules inside single-walled carbon nanotubes. The encapsulation of the so-obtained graphene nanoribbons is proved by atomic resolution electron microscopy, while their assignment is provided by a combination of an extensive wavelength-dependent Raman scattering characterization and quantum-chemical calculations. These findings enable a facile and scalable approach leading to the controlled growth and detailed analysis of well-defined sub-nanometer graphene nanoribbons.