Growth Kinetics of 0.5 cm Vertically Aligned Single-Walled Carbon Nanotubes

Zhong, Guofang; Iwasaki, Takayuki; Robertson, John; Kawarada, Hiroshi

doi:10.1021/jp067776s

Cited by 163 publications

(162 citation statements)

References 30 publications

(68 reference statements)

Supporting

Mentioning

158

Contrasting

Order By: Relevance

“…Tortuosity τ in our estimation was approximated to 1.5 in all cases, because it is the typical value for aligned MWNTs (ref 26). As discussed in the main text, error here will not significantly affect in the overall conclusions, i.e.…”

mentioning

confidence: 89%

“…However, the influences of these parameters are very limited because to bring diffusion limited processes to the reaction controlled region one usually needs to decrease φ by two orders of magnitude, as expressed in Equation (7). One promising approach is to pattern the continuous CNT film into pillar-like or sheet-like micron structure to allow easy side diffusion, as demonstrated by Zhong et al 26 However, we found this strategy didn't work for our F-MWNT in yielding longer CNT arrays. 30 This means there exists strong diffusion resistance in P-SWNT but not in F-MWNT, which agrees well with the above calculated results on these two situations.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Growth Deceleration of Vertically Aligned Carbon Nanotube Arrays: Catalyst Deactivation or Feedstock Diffusion Controlled?

et al. 2008

View full text Add to dashboard Cite

Feedstock and byproduct diffusion in the root growth of aligned carbon nanotube arrays is discussed. A non-dimensional modulus is proposed to differentiate catalyst-poisoning controlled growth deceleration from one which is diffusion controlled. It is found that, at current stage, aligned multi-walled carbon nanotube arrays are usually free of feedstock diffusion resistance while single-walled carbon nanotube arrays are already suffering from a strong diffusion resistance. The method presented here is also able to predict the critical lengths in different CVD processes from which carbon nanotube arrays begin to meet strong diffusion resistance, as well as the possible solutions to this diffusion caused growth deceleration. * To whom correspondence should be addressed.Fei Wei, weifei@flotu.org, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; tel, 86-10-62788984; fax, 86-10-62772051.Shigeo Maruyama, maruyama@photon.t.u-tokyo.ac.jp, Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Japan; tel, fax, Vertically aligned carbon nanotube (CNT) arrays grown on flat substrates [1][2][3][4][5][6][7] , in which all the nanotubes are of similar orientation and length, offer an ideal platform to study CNT growth mechanisms and kinetics. Since 1996 1 , various chemical vapor deposition (CVD) methods, including floating catalytic CVD 2 , plasma enhanced CVD 3 and thermal CVD 4 have been proposed to synthesize aligned multi-walled carbon nanotube (MWNT) arrays. Lately, alcohol catalytic CVD 5 (ACCVD), water assisted CVD 6 , microwave plasma CVD 7 , etc. are used to produce vertically aligned single-walled carbon nanotube (SWNT) arrays. These processes usually involve different catalysts, carbon sources and operation parameters, resulting in products with different morphologies and qualities. However, none of these CNT growth processes can overcome the gradual deceleration and eventual termination of growth. The ability to understand and thereby to overcome the underlying deactivation mechanisms becomes one of the most critical steps to develop nano-scale tubes into real macroscopic materials. Recently, many groups have affirmed the root growth mode of their vertically aligned CNTs, indicating that the feedstock molecules have to diffuse through the thick CNT array, reach the substrate where catalysts are located, and then contribute to the CNT growth. [8][9][10][11][12][13] In this bottom-up growth process, the diffusion resistance of the feedstock from the top to the root arises as an obstruction, and can act as a unique decelerating growth mechanism. Existence of a feedstock diffusion resistance means that concentration of the carbon source at the CNT root should be lower than the bulk concentration. Previously, Zhu et al.14 fitted experimentally-obtained film thicknesses with the square root of growth time, and stated that the growth deceleration is attributed to the strong diffusion limit of feedstock to the CNT root. However, Hart et al. 15 claimed later tha...

show abstract

mentioning

confidence: 89%

mentioning

confidence: 99%

Growth Deceleration of Vertically Aligned Carbon Nanotube Arrays: Catalyst Deactivation or Feedstock Diffusion Controlled?

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Water also reacts with the wall of nanotubes even though the wall is more impervious to oxidation than carbonaceous impurities. 11 Plasma generally activates carbon source molecules so that not only the nanotube growth but also the deposition of carbonaceous impurities occurs at lower temperature in plasma CVD than in thermal CVD. Therefore, the larger amount of water in our plasma CVD is necessary to enhance and preserve catalyst activity by removing larger amount of carbonaceous impurities on the catalyst surface.…”

Section: Resultsmentioning

confidence: 99%

Low Temperature Growth of Single-walled Carbon Nanotube Forest

Lee¹,

Im²,

Kim³

et al. 2010

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

Forest of single-walled carbon nanotubes (SWNTs) was grown at 450 o C by water-plasma chemical vapor deposition using ultrathin iron on alumina supporting film. The growth rate of the SWNT forest is ~ 0.9 µm/min, and the diameters of nanotubes are mainly in a range of 3.0 ~ 3.5 nm. The low intensity ratio of D-to G-band (ID/IG ~ 0.098) in Raman spectra indicates that our SWNT forest grown at 450 o C is fairly pure and crystalline. This low temperature growth of SWNT forest may enable variable applications requiring the vertically-aligned nanotubes to obtain large surface area.

show abstract

“…9) Over the last few years, there have been many reports on the synthesis of VACNTAs using CVD-based methods. Many of these techniques, however, have stronger requirements on the equipment, 10), 11) limiting CNT production to only the laboratory range. More have focused on preparing ideal catalysts on the surface of substrates because it is generally believed that catalysts play a critical role in the synthesis of CNTs.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of vertically-aligned CNT arrays from diameter-controlled Fe<sub>3</sub>O<sub>4</sub> nanoparticles

Zhao

Seo

Gong

et al. 2014

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

Almost monodisperse Fe 3 O 4 nanoparticles (NPs) with four distinct mean sizes prepared by thermal decomposition were selfassembled onto a silicon substrate in the form of multi-layers using a simple drop-drying method. These multilayered Fe 3 O 4 NPs were used as the catalysts to grow vertically-aligned carbon nanotube arrays (VACNTAs) by chemical vapor deposition (CVD). The correlation between the CNT diameter and the NP size was determined. Catalysts with different sizes play a vital role in influencing the diameters and structures of CVD-grown CNTs. In addition, the size of the catalyst NPs is a critical factor for obtaining dense arrays of VACNTs. This method is a relatively simple and environmental friendly process compared to previous methods, and has the potential for the mass production of VACNTAs.

show abstract

Growth Kinetics of 0.5 cm Vertically Aligned Single-Walled Carbon Nanotubes

Cited by 163 publications

References 30 publications

Growth Deceleration of Vertically Aligned Carbon Nanotube Arrays: Catalyst Deactivation or Feedstock Diffusion Controlled?

Growth Deceleration of Vertically Aligned Carbon Nanotube Arrays: Catalyst Deactivation or Feedstock Diffusion Controlled?

Low Temperature Growth of Single-walled Carbon Nanotube Forest

Synthesis of vertically-aligned CNT arrays from diameter-controlled Fe<sub>3</sub>O<sub>4</sub> nanoparticles

Contact Info

Product

Resources

About