Effect of pyrolysis temperature on the microstructure of disordered carbon nanowires

Samuel, B. A.; Rajagopalan, Ramakrishnan; Foley, Henry C.; Haque, M. Shamsul

doi:10.1016/j.tsf.2010.07.066

Cited by 8 publications

(5 citation statements)

References 43 publications

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“…By these later stages of carbonization, when HTTs increase toward 1000 °C, the distorted graphene regions are likely to resemble the topological defects or “quasi-amorphous carbon” observed in reduced graphene oxide and the kinds of fullerene-related, curved/saddle-point structures illustrated by Harris et al A similar concept of conversion from heteroatom-dominated strain at HTTs ≈ 600 °C, to cross-link-dominated strain at HTTs ≈ 900 °C, to pentagonal- and heptagonal-ring-dominated strain at HTTs ≈ 1500 °C has been proposed to explain how the G-band position in the Raman spectrum changes as polyfurfuryl alcohol nanowires were carbonized …”

Section: Updated Modelmentioning

confidence: 90%

“…By these later stages of carbonization, when HTTs increase toward 1000 °C, the distorted graphene regions are likely to resemble the topological defects or "quasi-amorphous carbon" observed in reduced graphene oxide 45 and the kinds of fullerene-related, curved/saddle-point structures illustrated by Harris et al 29 A similar concept of conversion from heteroatom-dominated strain at HTTs ≈ 600 °C, to crosslink-dominated strain at HTTs ≈ 900 °C, to pentagonal-and heptagonal-ring-dominated strain at HTTs ≈ 1500 °C has been proposed to explain how the G-band position in the Raman spectrum changes as polyfurfuryl alcohol nanowires were carbonized. 92 In this postulated model, these distorted graphene regions are important as covalent, conjugated, and thermally stable cross-links/bridges between multiple regular graphene domains that have collided while growing in three dimensions. As the nanostructure develops with aromatic growth, fjord closure, and oxygen functional groups removed as H 2 O, CO 2 , and CO, some of the distorted graphene is converted into regular graphene.…”

Section: Energy and Fuelsmentioning

confidence: 99%

See 1 more Smart Citation

Reviewing, Combining, and Updating the Models for the Nanostructure of Non-Graphitizing Carbons Produced from Oxygen-Containing Precursors

2016

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Following a review of the literature evidence, an updated model is presented to describe the kind of nanometer-scale structures that occur in non-graphitizing carbons (also known as chars, biocarbons, and biochars) produced from the carbonization of oxygen-containing precursors (especially carbohydrates and lignocellulosic biomass). This is not intended to be a new model, because it is still essentially the same general model and concepts put forward by Franklin in 1951 and updated through integrating additional experimental evidence, ideas, and key features published over the last 64 years. The updated model uses evidence and concepts from recent publications on graphene oxide and reduced graphene oxide to assist in explaining a potential role of heteroatoms (especially oxygen) in the cross-linking, which is considered important in the development of the distinct nanostructure of non-graphitizing carbons. A three-dimensional molecular/atomic model is presented to approximate the nanostructure formed as carbonization temperatures approach 1000 °C. The development of this nanostructure over a range of carbonization temperatures is also described.

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Section: Updated Modelmentioning

confidence: 90%

Section: Energy and Fuelsmentioning

confidence: 99%

Reviewing, Combining, and Updating the Models for the Nanostructure of Non-Graphitizing Carbons Produced from Oxygen-Containing Precursors

2016

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“…They employed a template-based fabrication process, where the capillary forces align polyfurfuryl alcohol chains in the form of nanowires with a diameter of 100–200 nm. The observed significant change in atomic rearrangement was explained by the alignment of precursor chains during the templated synthesis . In summary, the key factor for obtaining graphite, that is, with the same lamellar nanostructure in which BSUs are oriented in parallel over a very long range (≫1 μm), can also be obtained by other means: condensation of a carbon vapor on a planar substrate or different processes of templating.…”

Section: Introductionmentioning

confidence: 99%

“…observed significant change in atomic rearrangement was explained by the alignment of precursor chains during the templated synthesis. 7 In summary, the key factor for obtaining graphite, that is, with the same lamellar nanostructure in which BSUs are oriented in parallel over a very long range (.1 μm), can also be obtained by other means: condensation of a carbon vapor on a planar substrate 8 or different processes of templating. All of these carbon precursors are progressively graphitizable under heat treatment at 3000 °C and undergo a "standard" graphitization process similar to that of petroleum cokes or pitch cokes.…”

Section: Introductionmentioning

confidence: 99%

Comparative XRD, Raman, and TEM Study on Graphitization of PBO-Derived Carbon Fibers

et al. 2011

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Carbon fibers, obtained by carbonizing poly(p-phenylene benzobisoxazole) (PBO) fibers at 900 °C, graphitize extensively upon heat treatment at higher temperatures (2700 °C). In this work, XRD, Raman spectroscopy, and HRTEM are used to monitor the structural and nanostructural transformations of the carbon material under heat-treatment at several temperatures in the interval 900–2800 °C. These different techniques provide complementary information, especially regarding the spatial resolution they achieve. They highlight a specific nonconventional mode of graphitization for this unexpectedly graphitizable precursor. The reliability in the determination of L a crystallite sizes from these three techniques is compared and discussed. The existence of four steps in the graphitization of PBO-derived carbon fibers is inferred.

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“…The products obtained by this processes range from selective membranes, 1 carbon microspheres, 2,3 hydrophobic surfaces, 4 activated nanoporous carbon, 5 carbon nanowires 6 to monolithic vitreous carbon 7 products. The Monolithic Vitreous Carbon material (MVC), which was studied in this article, is characterized by low density, good electrical conductivity, gas impermeability, resistance to high temperatures, biocompatibility, and chemical inertness.…”

Section: Introductionmentioning

confidence: 99%

Acid catalyst influence on the polymerization time of polyfurfuryl alcohol and on the porosity of monolithic vitreous carbon

Origo¹,

Arisseto²,

Seixas

et al. 2016

J of Applied Polymer Sci

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This study compares the influence of different acid catalysts on the polymerization rate of polyfurfuryl alcohol (PFA) precursor and especially on the respective porosity of Monolithic Vitreous Carbon (MVC) produced from that. Five acid catalysts commonly used were compared: p-toluenesulfonic (PTLS), hydrochloric, sulfuric, nitric, and phosphoric. A fixed molar concentration of catalyst was diluted in PFA resin under room pressure and temperature. The time dependence of PFA resin polymerization was investigated by optical transmittance of PFA films, and the polymerization degree, characterized by ATR spectroscopy and thermogravimetry. MVC samples prepared with the same PFA resin and each catalyst were carbonized up to 1200 8C, under inert atmosphere. MVC porosity was studied by nitrogen adsorption/desorption, and by SEM and optical microscopy. Higher polymerization degree and higher residual mass were obtained with faster catalysts. No direct relation between the polymerization rate and the acid force was observed. PTLS promoted the fastest PFA polymerization process and the sulfuric acid, the slowest one. MVC samples were obtained by slow carbonization. MVC presented low specific surface S BET from 1.4 to 7.4 m 2 /g. Nitric acid catalyst contributed the most to micropores formation. Micrometric apparent porosity was smaller for the catalysts having longer polymerizations times, such as phosphoric and sulfuric acid. Phosphoric catalyst corresponded to the lowest porosity in MVC. As the polymerization time increased, the average size of the micrometric surface pores tended to augment. The MVC macroscopic porosity increased with the S BET increment. Acid catalysts choice exerted a fundamental role on the porosity of MVC. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43272.

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Effect of pyrolysis temperature on the microstructure of disordered carbon nanowires

Cited by 8 publications

References 43 publications

Reviewing, Combining, and Updating the Models for the Nanostructure of Non-Graphitizing Carbons Produced from Oxygen-Containing Precursors

Reviewing, Combining, and Updating the Models for the Nanostructure of Non-Graphitizing Carbons Produced from Oxygen-Containing Precursors

Comparative XRD, Raman, and TEM Study on Graphitization of PBO-Derived Carbon Fibers

Acid catalyst influence on the polymerization time of polyfurfuryl alcohol and on the porosity of monolithic vitreous carbon

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