Double wall carbon nanotubes promoted by sulfur in a floating iron catalyst CVD system

Ci, Lijie; Rao, Zhonghao; Zhou, Zhenping; Tang, Dongsheng; Yan, Xiaoqin; Liang, Y. X.; Liu, Dongfang; Yuan, Huajun; Zhou, Weiya; Wang, Gang; Liu, Wei; Xie, Sishen

doi:10.1016/s0009-2614(02)00600-0

Cited by 163 publications

(121 citation statements)

References 18 publications

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“…3,4 Moreover, several research groups obtained large quantities of DWNTs by the catalytic decomposition of methane, while the chemical vapor deposition (CVD) process is used to control the reaction parameters precisely. [5][6][7] However, the two constituent tubes of the DWNTs have not yet been characterized in detail. Basca et al 8 and Bandow et al 3,9 characterized their DWNTs by measuring the Raman spectra, and most of their radial breathing mode (RBM) frequencies RBM were found to be greater than 200 cm −1 , which are in accordance with DWNTs that have small diameter inner constituents.…”

Section: Introductionmentioning

confidence: 99%

Identification of the constituents of double-walled carbon nanotubes using Raman spectra taken with different laser-excitation energies

Chou

Ren

et al. 2003

J. Mater. Res.

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Double-walled carbon nanotubes (DWNTs), synthesized by the catalytic decomposition of methane, were explored by resonance Raman spectroscopy using different energies for laser excitation. Based on the radial breathing mode frequencies, the indices of the two layers of a DWNT were approximately assigned, depending on the interlayer separation of the two coaxial layers of the DWNT, which ranged from 0.34 to 0.40 nm. From the tentatively assigned results, it was found that the two walls of the DWNT are not strongly selected by chirality and diameter. The results, however, suggest that, for the tubes that are resonant with the available laser excitation energies, most of the outer layers of the observed DWNTs in our samples are semiconducting, while the inner layers of the observed DWNTs are either semiconducting or metallic based on the assembled DWNTs. The characteristics of the G, D, and GЈ band of the DWNTs are discussed, and a double peak feature in the D and GЈ band, originating from the inner and outer layers of the DWNTs, is reported.

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Section: Introductionmentioning

confidence: 99%

Identification of the constituents of double-walled carbon nanotubes using Raman spectra taken with different laser-excitation energies

Chou

Ren

et al. 2003

J. Mater. Res.

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“…Although our original intention by adding sulfur was to improve the production rate of SWNTs, most of the nanotubes in the products consist of two concentric graphene layers (DWNTs). We reported here that DWNTs were mass-produced by pyrolizing C 2 H 2 at the temperature range of 900-1100 8C on the floating iron catalyst with sulfur added [25][26][27]. Morphology of as-grown DWNTs is shown in Fig.…”

Section: Morphology Of the As-grown Dwntsmentioning

confidence: 91%

“…Otherwise, Iijima and coworkers reported that SWNTs and DWNTs could be produced synchronously by the decomposition of methane on mesoporous silica, whereas the zeolite support material is reported to yield only SWNTs [22]. In this paper, we have selectively synthesized single-or double-walled carbon nanotubes by the floating catalyst CVD method during the past three years [23][24][25][26][27]. In our studies, we reported that C 2 H 2 could be a very ideal carbon feedstock to produce clean and pure SWNTs by controlling the experimental parameters carefully.…”

Section: Introductionmentioning

confidence: 93%

Controllable preparation and properties of single-/double-walled carbon nanotubes

Xie

Ci³

et al. 2005

Science and Technology of Advanced Materials

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In this paper, we discussed recent studies done in our laboratories with a floating catalyst chemical vapor deposition (CVD) method. We can grow single-or double-walled carbon nanotubes (SWNTs/DWNTs) with different kinds of catalysts. Single-walled carbon nanotubes without amorphous carbon coating were prepared by thermally decomposing acetylene (C 2 H 2 ) at the temperature range of 750-1200 8C with ferrocene as catalyst. While with sulfur promoted ferrocene catalyst, double-walled carbon nanotubes were mass-produced by pyrolizing C 2 H 2 at the temperature range of 900-1100 8C. Furthermore, tunable growth of DWNTs with different diameter was achieved in our experiment. It is found that DWNTs produced at lower carbon partial pressure have much smaller inner tubes, even DWNTs with the smallest inner diameter of 0.4 nm was found in here. As convenient and effective tool, radial breathing mode (RBM) of Raman scattering technique can be used to distinguish SWNTs from DWNTs. In further studies of Raman scattering with DWNTs, the possible match of the inner tubes and the outer tubes according to the RBM bands was assigned, and different chirality types were discussed according to the diameter and chirality dependence of resonant Raman vibration. We also investigated the temperature-dependent frequency shift of resonant Raman spectra of DWNTs in the range of 78-650 K. We found that different RBM peaks, which are relative to different tube diameters, have different temperature coefficient of frequency shift, and the larger diameter carbon nanotubes have more RBM frequency downshift with increasing temperature. It is ascribed to the RBM frequency variation to the temperature dependence of the stretching force constant of C-C bond. Besides, Polarized Raman spectra were preformed on well-aligned SWNTs structure fabricated through post-growth method and found that the angular dependence of Raman intensity is consistent well with the predictions of the resonance Raman theory. q

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“…Recently, the addition of sulfur was found to be effective in promoting the growth and yield of single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) [20][21][22][23]. More recently, vertically aligned SWCNT film was grown by thermal CVD using ethanol decomposition over a mono-dispersed Co-Mo catalyst on quartz substrates [24,25], and water-stimulated enhanced catalytic activity resulted in massive growth of superdense and vertically aligned SWCNT forests with heights up to 2.5 mm [26].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of well-aligned thin multiwalled carbon nanotubes on the silicon substrate and their field emission properties

Yuan¹,

Shin²,

Kim³

et al. 2011

Carbon letters

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Well-aligned multi-walled carbon nanotubes (MWCNTs) were successfully synthesized by catalytic chemical vapor deposition using a hydrogen sulfide (H 2 S) additive onto Al/Fe thin film deposited on Si wafers. Transmission electron microscopy images indicated that the as-grown carbon products were thin MWCNTs with small outer diameters of less than 10 nm. H 2 S plays a key role in synthesizing thin MWCNTs with a large inside hollow core. The well-aligned thin MWCNTs showed a low turn-on voltage of about 1.1 V/μm at a current density of 0.1 μA/cm 2 and a high emission current of about 1.0 mA/cm 2 at a bias field of 2.3 V/μm. We suggest a possible growth mechanism for the well-aligned thin MWCNTs with a large inside hollow core.

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Double wall carbon nanotubes promoted by sulfur in a floating iron catalyst CVD system

Cited by 163 publications

References 18 publications

Identification of the constituents of double-walled carbon nanotubes using Raman spectra taken with different laser-excitation energies

Identification of the constituents of double-walled carbon nanotubes using Raman spectra taken with different laser-excitation energies

Controllable preparation and properties of single-/double-walled carbon nanotubes

Synthesis of well-aligned thin multiwalled carbon nanotubes on the silicon substrate and their field emission properties

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