Preparation of highly oxidized nitrogen-doped carbon nanotubes

We report the synthesis of capsule-embedded reduced graphene oxide (rGO) by photocatalytic reduction in the presence of peanut shaped a-Fe 2 O 3 particles under visible light. This process is able to produce highly stabilized water dispersible rGO without the help of a stabilizer, which is suitable to make thin films on a glass substrate by the drop casting method. In addition, the evolution of the morphology with different visible light exposure times ranging from 5 to 120 minutes reveals that the catalyst leads to transformation of a few rGO sheets into capsules via a core-shell structure. These capsules are stable on the rGO sheet at a vacuum of 10 À9 Torr, but unstable under vacuum annealing at 400 C and 10 À5 Torr that created impressions on the rGO film. The bandgap of the capsule-embedded rGO decreases nonlinearly with the visible light exposure time; from 2.47 eV at 5 min to 1.73 eV at 120 min. The vacuum annealed rGO films on glass substrates show an electrical conductivity of 2000 S m À1 at 300 K and the conduction is dominated by two-dimensional variable range hopping. The formation of capsules is described based on electrostatic interactions in association with the dipole force of the monodispersed peanut shaped a-Fe 2 O 3 particles, whereas, the bandgap opening and high conductivity are attributed to the residual oxygen functional groups such as carbonyl (>C]O) and epoxy (C-O-C) on the rGO, in addition to the modulated surface morphology.

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“…46,47 As reported earlier, plotting 3 1/2 /l versus 1/l and extrapolating the linear region of the curve to the x-axis gives the bandgap. Fig.…”

Section: Resultsmentioning

confidence: 70%

Capsule-embedded reduced graphene oxide: synthesis, mechanism and electrical properties

et al. 2013

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“…A method for the preparation of highly oxidized NCNTs, using potassium permanganate+H 2 SO 4 solution, was described [384]. [394].…”

Section: Preparation Of O-containing Ncntsmentioning

confidence: 99%

One-dimensional nitrogen-containing carbon nanostructures

Ćirić‐Marjanović

Pašti

Mentus

2015

Progress in Materials Science

115

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“…10,23,31,32 Similar to the synthesis of GNRs, chemical unzipping of CN x -MWCNTs 23,31 is more preferred, due to the high yield and straightforward scalability, than using metallic nanoparticles 10 or thermal expansion techniques. 32 Silva et al 23 recently studied the effect of oxidation reaction parameters, such as time, temperature and the ratio of oxidizers, on the unzipping of CN x -MWCNTs.…”

mentioning

confidence: 99%

“…In addition, unraveling of the bamboo compartments in CN x -MWCNTs has been identified as a challenge in the literature with unsuccessful efforts reported to date. 23,31 Bamboo compartments, as the typical structural characteristics of CN x -MWCNTs, can be described as many capped short carbon nanotubes that are sequentially located inside the main MWCNTs.…”

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confidence: 99%

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

Yazdi

Chizari

Jalilov³

et al. 2015

ACS Nano

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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.

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Preparation of highly oxidized nitrogen-doped carbon nanotubes

Cited by 24 publications

References 20 publications

Capsule-embedded reduced graphene oxide: synthesis, mechanism and electrical properties

Capsule-embedded reduced graphene oxide: synthesis, mechanism and electrical properties

One-dimensional nitrogen-containing carbon nanostructures

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

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