Effect of NH3 environmental gas on the growth of aligned carbon nanotube in catalystically pyrolizing C2H2

Jung, Minjae; Eun, Kwang Yong; Baik, Young‐Joon; Lee, Kwang-Ryeol; Shin, Junho; Kim, Sung-Tae

doi:10.1016/s0040-6090(01)01442-0

Cited by 65 publications

(30 citation statements)

References 10 publications

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“…Also from our calculations it is clear that H atoms are formed to a large extent when NH 3 is used as the dilution gas (see figure 9a). In addition, a significant amount of atomic nitrogen is also predicted by our model, and this activated nitrogen can also affect the growth kinetics of CNT/CNF at the catalyst surface [53]. Finally, the NH 4 + ions are found to be the dominant ions, which agree well with the simulation results of Hash et al [26,27].…”

Section: Plasma Chemistry In the Different Gas Mixturessupporting

confidence: 88%

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Mao¹,

Bogaerts²

2010

J. Phys. D: Appl. Phys.

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To cite this version:M Mao, A Bogaerts. Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures. Journal of Physics D: Applied Physics, IOP Publishing, 2010, 43 (20) Abstract. A hybrid model, called the Hybrid Plasma Equipment Model (HPEM) was used to study an inductively coupled plasma in gas mixtures of H 2 or NH 3 with CH 4 or C 2 H 2 used for the synthesis of carbon nanotubes or carbon nanofibers (CNTs/CNFs). The plasma properties are discussed for the different gas mixture at low and moderate pressure, and the growth precursors for CNTs/CNFs are analyzed. It is found that C 2 H 2 , C 2 H 4 , and C 2 H 6 are the predominant molecules in CH 4 containing plasmas beside the feedstock gas, and serve as carbon sources for CNT/CNF formation. On the other hand, long chain hydrocarbons are observed in C 2 H 2 containing plasmas. Furthermore, the background gases CH 4 and C 2 H 2 show a different decomposition rate with H 2 or NH 3 addition at moderate pressures.

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Section: Plasma Chemistry In the Different Gas Mixturessupporting

confidence: 88%

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Mao¹,

Bogaerts²

2010

J. Phys. D: Appl. Phys.

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“…We hypothesize that the endothermic decomposition of ammonia may change the catalyst characteristics for the exothermic acetylene decomposition during CNF synthesis. It has also been proposed by other researchers that there is an effect on synthesis product due to atomic hydrogen [56] and/or atomic nitrogen [63] produced by decomposition of ammonia. These contributing factors may have modified the morphology of carbon deposits due to ammonia addition in the synthesis gas.…”

Section: Mechanism Of Cnf Synthesismentioning

confidence: 97%

“…• C [56,62,63]. Some researchers have proposed that atomic hydrogen [56] and/or atomic nitrogen [63] produced by the catalytic decomposition of ammonia keeps the catalyst active at high temperatures for synthesis of aligned CNF.…”

Section: Effects Of Ammonia In Synthesis Gasmentioning

confidence: 99%

“…Some researchers have proposed that atomic hydrogen [56] and/or atomic nitrogen [63] produced by the catalytic decomposition of ammonia keeps the catalyst active at high temperatures for synthesis of aligned CNF. Also, there are conflicting observations for the need of ammonia during synthesis of aligned CNF with some researchers proposing that ammonia is required only for the initial stage of synthesis [23] while some others proposing that ammonia is required during synthesis [56,61,64].…”

Section: Effects Of Ammonia In Synthesis Gasmentioning

confidence: 99%

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Carbon Nanofiber Synthesis within 3-Dimensional Sintered Nickel Microfibrous Matrices: Optimization of Synthesis Conditions

Karwa

Davis

Tatarchuk

2012

Journal of Nanotechnology

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This study focuses on the process of optimization for carbon nanofiber synthesis at the exterior and the interior of 3-dimensional sintered nickel microfibrous networks. Synthesis of carbon nanofibers (CNF) by catalytic decomposition of acetylene (ethyne) was conducted at atmospheric pressure and short reaction times (10 min). Two factors evaluated during the study were (a) CNF quality (observed by SEM and Raman spectroscopy) and (b) rate of reaction (gravimetrically measured carbon yield). Independent optimization variables included redox faceting pretreatment of nickel, synthesis temperature, and gas composition. Faceting resulted in an 8-fold increase in the carbon yield compared to an untreated substrate. Synthesis with varying levels of hydrogen maximized the carbon yield (9.31 mg C/cm 2 catalyst). The quality of CNF was enhanced via a reduction in amorphous carbon that resulted from the addition of 20% ammonia. Optimized growth conditions that led to high rates of CNF deposition preferentially deposited this carbon at the exterior layer of the nickel microfibrous networks (570 • C, 78% H 2 , 20% NH 3 , 2% C 2 H 2 , faceted Ni.). CNF growth within the 3-dimensional nickel networks was accomplished at the conditions selected to lower the gravimetric reaction rate (470 • C, 10% H 2 , 88% N 2 , 2% C 2 H 2 , nonfaceted Ni).

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“…In the growth of CNTs, the composition plays an important role in determining their morphologies and properties. The reaction gases, in particular, NH 3 , can have a great effect on the diameters, lengths, and population densities of CNTs [8], but the effects have been controversial and are not yet clear.…”

Section: Introductionmentioning

confidence: 99%

Field Emission from Carbon Nanotubes Etched by a dc Plasma

Cho¹,

Lee²,

Jang³

et al. 2007

J. Korean Phys. Soc.

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This study investigates the effect of NH3 gas upon the growth of carbon nanotubes (CNTs) using thermal chemical vapor deposition. It is considered that the CNT synthesis is thought to occur mainly through two steps, clustering of catalyst particles followed by growth of CNTs. We, thus, introduced NH3 during either an annealing or growth step. When NH3 was fed only during annealing, CNTs grew longer and were more highly crystalline with their diameters unchanged. Addition of NH3 during growth, however, resulted in shorter CNTs with lower crystallinity and increased diameters. Vertically aligned, highly populated CNT samples showed poor field emission characteristics, leading us to apply post-treatment onto the CNT surface. The CNTs were etched back by dc plasma of N2 to reduce the population density and the radius of curvatures of CNTs, which resulted in a considerable improvement of the field emission characteristics.

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Effect of NH3 environmental gas on the growth of aligned carbon nanotube in catalystically pyrolizing C2H2

Cited by 65 publications

References 10 publications

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Carbon Nanofiber Synthesis within 3-Dimensional Sintered Nickel Microfibrous Matrices: Optimization of Synthesis Conditions

Field Emission from Carbon Nanotubes Etched by a dc Plasma

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