Helical and Dendritic Unzipping of Carbon Nanotubes: A Route to Nitrogen-Doped Graphene Nanoribbons

Abstract

Bamboo structured nitrogen-doped multiwalled carbon nanotubes (CN x -MWCNTs) have been successfully unzipped by a chemical oxidation route, resulting in nitrogen-doped graphene nanoribbons (CN x -GNRs) with a multifaceted microstructure. The oxidation of CN x -MWCNTs was carried out using potassium permanganate in the presence of trifluoroacetic acid or phosphoric acid. On the basis of the high resolution transmission electron microscopy studies, the bamboo compartments were unzipped via helical or dendritic mechanisms, which are different from the longitudinal unzipping of open channel MWCNTs. The product graphene oxide nanoribbons were simultaneously reduced and doped with nitrogen by thermal annealing in an ammonia atmosphere. The effects of the annealing temperature, time, and atmosphere on the doping level and types of the nitrogen functional groups have been investigated. X-ray photoelectron spectroscopy results indicate that a wide range of doping levels can be achieved (4–9 at %) simply by changing the annealing conditions. Pyridinic and pyrrolic nitrogen functional groups were the dominant species that were attached to the edges of the CN x -GNRs. The GNRs, with a faceted structure and pyridinic and pyrrolic groups on their edges, have abundant nitrogen sites. These active sites could play a vital role in enhancing the electrocatalytic performance of GNRs.

Artificial solid electrolyte interphase for aqueous lithium energy storage systems

“…S1B show a slight blueshifting of the G band (1580 to 1595 cm −1 ) and a significant contribution of the D band ( I D / I G = 0.92) in GO compared to the graphite precursor ( I D / I G = 0.34), mainly due to the incorporation of oxygen functionalities into the graphene network. In agreement with previous reports ( 35 , 36 ), a higher contribution of the D band ( I D / I G = 0.99) was detected in the RGO (fig. S1B) due to an increase in the number of aromatic domains responsible for the D band, but not necessarily their overall size, which is responsible for the G band.…”

“…( 35 ) with slight modifications in the procedure to obtain GO sheets with lower defects and larger flake sizes. In a typical procedure, 3 g of graphite was stirred in 360 ml of concentrated H 2 SO 4 for 1 hour.…”

Direct Creation of Highly Conductive Laser‐Induced Graphene Nanocomposites from Polymer Blends

“…The second stage involves hydrolysis of the carbonate linkage in PC and/or decomposition of imide groups in PEI, both occur at about the same temperature (≈600 °C), but with different mass loss. The PEI‐LIG, however, showed a single decomposition/carbon oxidation stage at ≈630 °C, very similar to the graphene powder that was previously reported . The TGA results, in general, confirm that the formation of higher concentrations of the LIG phase in the PC polymer (PC10‐LIG) can enhance the thermal stability of the final nanocomposites.…”

“…Graphene, a hexagonal sp 2 conformation of carbon atoms, was discovered in 2004, followed by the Nobel Prize in Physics in 2010, and since tremendous attention has been given to it worldwide due to its unique properties. Graphene not only has diverse chemistry and shapes from sheet to nanoribbon to quantum dot, but also is utilized for versatile applications in electronics, biomedicine, membrane‐based technologies, energy storage, and sports equipment. Stankovich et al took the initiative to utilize the superb electrical conductivity properties of graphene in insulating polymers.…”

Graphene-based Materials in Gas Sensor Applications: A Review

“…Methods such as chemical vapor deposition (CVD), mechanical exfoliation/cleavage of natural graphite, electric arc discharge, epitaxial growth, unzipping of CNTs, and solution-based reduction of GO are well known. (36)(37)(38)(39) Many have agreed that graphene is most suitable for electronic purposes as a 2D crystal consisting of not more than 10 graphene layers; (40) more than these, the thin film has a much more complicated 3D electronic band structure. Thus, choosing the suitable graphene synthesis process should be approached with utmost consideration.…”