Carbyne: electrochemical preparation and nanotube formation

Yasuda, Ayumu; Kawase, Noboru; Matsui, Taisuke; Shimidzu, Takeo; Yamaguchi, Chiharu; Matsui, Hisaji

doi:10.1016/s1381-5148(99)00017-6

Cited by 24 publications

(31 citation statements)

References 29 publications

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“…23,24 Later on, the efforts to study polyynes in a laboratory environment stimulated the discovery of C 60 and, consequently, they have been considered as possible intermediates in the production of fullerenes. [25][26][27] Furthermore, it is conceivable that polyynes play an important role in carbon nanotube formation, 28,29 chemical vapor deposition (CVD) processes of diamond, 30,31 and the formation of diamond-like carbon phases. 32 To fully understand the role of polyynes in the chemistry of combustion, planetary atmospheres, and other gas phase media, studies of reaction mechanisms and the product distributions of those polyyne-forming reactions are critically needed.…”

Section: Introductionmentioning

confidence: 99%

A combined ab initio and photoionization mass spectrometric study of polyynes in fuel-rich flames

Hansen

Klippenstein

Westmoreland

et al. 2008

Phys. Chem. Chem. Phys.

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Polyynic structures in fuel-rich low-pressure flames are observed using VUV photoionization molecular-beam mass spectrometry. High-level ab initio calculations of ionization energies for C2nH2 (n=1-5) and partially hydrogenated CnH4 (n=7-8) polyynes are compared with photoionization efficiency measurements in flames fuelled by allene, propyne, and cyclopentene. C2nH2 (n=1-5) intermediates are unambiguously identified, while HC[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C-CH=C=CH2, HC[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C-CH=CH2 (vinyltriacetylene) and HC[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C-CH[double bond, length as m-dash]CH-C[triple bond, length as m-dash]CH are likely to contribute to the C7H4 and C8H4 signals. Mole fraction profiles as a function of distance from the burner are presented. C7H4 and C8H4 isomers are likely to be formed by reactions of C2H and C4H radicals but other plausible formation pathways are also discussed. Heats of formation and ionization energies of several combustion intermediates have been determined for the first time.

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Section: Introductionmentioning

confidence: 99%

A combined ab initio and photoionization mass spectrometric study of polyynes in fuel-rich flames

Hansen

Klippenstein

Westmoreland

et al. 2008

Phys. Chem. Chem. Phys.

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“…[37][38][39] As for CNTs, the polyyne-route formation has been shown to work experimentally, as well. 40,41 The process employed in this paper is associated with a special "thermally removable protection layer technique," 34 to handle the unstable polyyne-containing carbons, which are damaged by water, oxygen, and light in air. This process features two advantages: in-situ observation of the growth, and formation of CNTs directly on a substrate.…”

Section: Introductionmentioning

confidence: 99%

Graphitization Mechanism during the Carbon-Nanotube Formation Based on the In-Situ HRTEM Observation

et al. 2002

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The mechanism of the carbon nanotube (CNT) formation and its graphitization has not been well understood and is still under controversy. The authors have been studying a new process to form CNTs, where polyynecontaining carbons are heated and irradiated by an electron beam in a transmission electron microscope (TEM). The technique is compatible to an in-situ observation and was applied to a high-resolution TEM (HRTEM) to elucidate the graphitization mechanism. The observation shows that micro-graphenes exist from the beginning of the formation process and develop to form highly ordered graphene layers through fusion and rearrangement of the premature layers, accompanied by evaporation of micro-graphenes. The CNT formation mechanism focusing on its graphitization is presented and discussed.

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“…Further, linear polyynes have recently been synthesized in high yield by arcing graphite electrodes in a number of solvents (distilled water, liquid nitrogen, methanol, etc.) While the exact role that the gaseous products play in CNT formation is not yet clear, linear polyynes have been implicated in the formation of soot (29) and MWCNTs (30) and could also play a role in the mechanism of the products formed in this study. The source of the carbon for these linear polyynes was in all cases supplied by Hydrogen and Helium Mixtures and Carbon Nanotube Synthesis the graphite, while the atoms that capped the polyyne were supplied by the solvent.…”

Section: S H Durbach Et Al 162mentioning

confidence: 93%

The Effect of Hydrogen, Helium and Their Mixtures on the Synthesis of Carbon Nanotubes in a DC Arc‐Discharger

Durbach¹,

Witcomb

Coville

2005

Fullerenes, Nanotubes and Carbon Nanostructures

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Multiwalled carbon nanotubes (MWCNTs) have been produced with a DC arc-discharger in the presence of hydrogen, helium or hydrogen-helium mixtures using high gas pressures (60 kPa-140 kPa) and varying gas pressure ratios (10%-100% hydrogen in helium at 100 kPa). Variation of He pressure hardly affected the cathode deposit formation while increased H 2 pressure resulted in an increase in chamber soot and cathode material formation but a relative decrease in the % MWCNT production. Varying H 2 /He gas ratios at a constant total pressure of 100 kPa revealed that increasing H 2 content gave increased cathode deposit formation because of a faster anode consumption rate as well as more total gaseous product formation. Further, a maximum MWCNT deposit was obtained from a 50/50 gas mixture. GC-MS analysis of the gaseous products trapped from these reactions showed evidence for the presence of linear alkynes (ethyne, butyne, pentyne, hexyne etc.), benzene, naphthalene, anthracene, and their methylated analogues. The relative in-situ temperature of the reaction with the pure gases was monitored and revealed that the highest temperature was recorded for the reaction with 60 kPa H 2 , which also produced the maximum amount of MWCNTs (80%). Impure samples from the cathode deposit were analysed by TEM and showed that in the majority of cases rectangular closed-tipped nanotubes were synthesised, together with varying amounts of onion-like sheets and folded graphene sheets.

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Carbyne: electrochemical preparation and nanotube formation

Cited by 24 publications

References 29 publications

A combined ab initio and photoionization mass spectrometric study of polyynes in fuel-rich flames

A combined ab initio and photoionization mass spectrometric study of polyynes in fuel-rich flames

Graphitization Mechanism during the Carbon-Nanotube Formation Based on the In-Situ HRTEM Observation

The Effect of Hydrogen, Helium and Their Mixtures on the Synthesis of Carbon Nanotubes in a DC Arc‐Discharger

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