Investigation of semicommercial arc plants for fullerene-production

Алексеев, Н. И.; Filippov, B. M.; Basargin, I. V.; Sedov, A.I.

doi:10.1007/s10891-011-0570-0

Cited by 9 publications

(10 citation statements)

References 3 publications

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“…Initially, a single I h -C 60 molecule was placed inside the center of the walls sphere. The initial temperature for the molecular dynamics was 6000 K, and the system was annealed for 50 ps, which is typical of arc jet experiments . This vaporized the C 60 and gave a representative of the state found during the early stages of laser ablation or arc jet fullerene experiments.…”

Section: Methodsmentioning

confidence: 99%

“…Being enclosed carbon cages, fullerenes are curved, and this curvature induces a strain energy that reduces the stability of smaller fullerenes. 24 Paradoxically, in the case of high temperature arc jet 25 or the laser ablation methods 26 used to produce them, small fullerenes, such as C 60 and C 70 , form in significant amounts. 27 There have been several attempts to explain this paradox, including the isolated pentagon rule 27 or the kinetic stability model, 24 but a full mechanistic understanding is still elusive.…”

Section: ■ Introductionmentioning

confidence: 99%

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Role of Graphitic Bowls in Temperature Dependent Fullerene Formation

et al. 2022

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Fullerenes are used extensively in organic electronics as electron acceptors among other uses; however, there are still several key mysteries regarding their formation such as the importance of graphitic intermediates and the thermokinetics of initial cage formation. To this end, we have conducted density functional tight binding molecular dynamics (DFTB-MD) calculations on disintegrated I h -C60 to investigate the formation mechanisms of fullerenes at high temperature conditions. From the results of these DFTB-MD calculations we were able to develop a thermokinetic model to describe the free energies and kinetics of fullerene formation at a range of temperatures. Direct observation of the mechanism revealed fullerenes readily forming in nanosecond times between 2000 and 3000 K but were hindered above this temperature window. Analysis revealed temperature dependent formation mechanisms where at low temperatures (<2750K) flat graphitic bowls play an important part as metastable intermediates while highly curved bowls follow a direct fast transformation. Meanwhile at higher temperatures (>2750 K), flat bowls become the transitory structure between chains and fullerene. Free energy analysis from our thermokinetic model shows this change in graphitic bowls to being transitory hinders fullerene formation at high temperatures compared to lower temperatures, essentially kinetically trapping C60 as chain networks. This investigation gives new key insights into the formation mechanisms of C60 fullerenes and highlights important intermediates while also illuminating the temperature window for fullerene formation, facilitating better optimization of experimental methods.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Role of Graphitic Bowls in Temperature Dependent Fullerene Formation

et al. 2022

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“…Since then, the scientific community has been interested in finding new methods that could be controlled to facilitate the synthesis of larger fullerenes and specific isomers with high yields and low costs. However, nowadays, the methods used for obtaining fullerenes in commercial scale are based on the vaporization of graphite by pyrolysis, radio‐frequency‐plasma, or arc discharge‐plasma techniques . All these methods have the same disadvantages as the one proposed by Krätschmer.…”

Section: Synthesis Of Fullerenes By Vaporization Of a Carbon Sourcementioning

confidence: 99%

Synthesis of fullerenes

Mojica

Alonso

Méndez

2013

J. Phys. Org. Chem.

109

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We present a review of the methods most frequently used for the synthesis of fullerenes and the changes that these methods have experienced since 1985 when Kroto and co-workers discovered C 60 . We also analyze the most important models that explain the mechanism of the formation of fullerenes in carbon soot, as well as the new methodologies that lead to the rational chemical synthesis of fullerenes and of fullerene fragments as precursors.

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“…Current methods for producing fullerene structures include the arc jet method and the laser ablation method, both high-energy methods that involve temperatures in excess of 5000 K. As such, these are multiple proposed fullerene formation mechanisms including the pentagon road, − fullerene road, ring coalescence, hot giant, − top-down/bottom-up mechanisms, closed network growth, and reformation of high-energy graphene flakes . However, with such high-energy/-temperature methods, where kinetics is often the deciding factor, there is no guarantee that ideal I h -C 60 will be the main product initially.…”

Section: Introductionmentioning

confidence: 99%

High Temperature Accelerated Stone–Wales Transformation and the Threshold Temperature of IPR-C₆₀ Formation

et al. 2021

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The Stone–Wales bond rotation isomerization of nonicosahedral C60 (C2v-C60) into isolated-pentagon rule following icosahedral C60 (Ih-C60 or IPR-C60) is a limiting step in the synthesis of Ih-C60. However, extensive previous studies indicate that the potential energy barrier of the Stone–Wales bond rotation is between 6 and 8 eV, extremely high to allow for bond rotation at the temperatures used to produce fullerenes conventionally. This is also despite data indicating a possible fullerene road mechanism that necessitates low-temperature annealing. However, these previous investigations often have limiting factors, such as using the harmonic approximation to determine free energies at high temperatures or considering only the reverse Ih-C60 to C2v-C60 transition as a basis. Indeed, when the difference in energy between Ih-C60 and C2v-C60 is accounted for, this barrier is generally reduced by ∼1.5 eV. Thus, utilizing the recently developed density functional tight binding metadynamics (DFTB-MTD) interface, the effects of temperature on the bond rotation in the conversion of C2v-C60 to Ih-C60 have been investigated. We found that Stone–Wales bond rotations are complex processes with both in-plane and out-of-plane transition states, and which transition path dominates depends on temperature. Our results clearly show that at temperatures of 2000 K, the free energy for a C2v-C60 to Ih-C60 transition is only ∼4.21 eV and further reduces to ∼3.77 eV at 3000 K. This translates to transition times of ∼971 μs at 2000 K and ∼34 ns at 3000 K, indicating that defect healing is a fast process at temperatures typical of arc jet or laser ablation experiments. Conversely, below ∼2000 K, bond rotation becomes prohibitively slow, putting a lower threshold limit on the temperature of fullerene formation and subsequent annealing.

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Investigation of semicommercial arc plants for fullerene-production

Cited by 9 publications

References 3 publications

Role of Graphitic Bowls in Temperature Dependent Fullerene Formation

Role of Graphitic Bowls in Temperature Dependent Fullerene Formation

Synthesis of fullerenes

High Temperature Accelerated Stone–Wales Transformation and the Threshold Temperature of IPR-C₆₀ Formation

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Investigation of semicommercial arc plants for fullerene-production

Cited by 9 publications

References 3 publications

Role of Graphitic Bowls in Temperature Dependent Fullerene Formation

Role of Graphitic Bowls in Temperature Dependent Fullerene Formation

Synthesis of fullerenes

High Temperature Accelerated Stone–Wales Transformation and the Threshold Temperature of IPR-C60 Formation

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Product

Resources

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High Temperature Accelerated Stone–Wales Transformation and the Threshold Temperature of IPR-C₆₀ Formation