CCVD Synthesis of Single- And Double-Walled Carbon Nanotubes: Influence of the Addition of Molybdenum to Fe−Al<sub>2</sub>O<sub>3</sub> Self-Supported Foams

Cordier, Anne; Resende, Valdirene Gonzaga de; Grave, E. De; Peigney, Alain; Billon, Laurent

doi:10.1021/jp806708z

Cited by 8 publications

(26 citation statements)

References 32 publications

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“…The conditions required for the formation of DWNTs and SWNTs have been investigated independently. These include catalyst particle size [25][26][27], carbon source flow rate [28], catalytic material composition [29], and tempera- ture [26,30]. However, there are some contradictions between these studies, as the parameters are not always investigated at the same time.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of High-Quality Single- and Double-Walled Carbon Nanotubes on Fe/MgO Catalysts

Kashi

Aghababazadeh

Arabi

et al. 2016

Nanomaterials and Nanotechnology

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In this study, Fe/MgO catalysts with three different iron contents (5, 10, and 15 wt.%) were prepared by three catalyst preparation methods: impregnation, solution combustion synthesis, and co-calcination of metal nitrates. The resulting catalysts were subjected to methane at 900°C in order to grow carbon nanotubes (CNTs). The powders and products were then studied by X-ray diffraction (XRD), differential thermal analysis (DTA), scanning and transmission electron microscopy (SEM and TEM), and Raman spectroscopy. Formation of MgFe 2 O 4 upon heating the catalysts to 900°C was confirmed by XRD. After the growth step, corresponding peaks of MgFe 2 O 4 disappeared and metallic iron peaks appeared, indicating that MgFe 2 O 4 is the responsible phase for production of iron nanoparticles. HRTEM images showed that the product on the 5 wt.% catalysts was mostly SWNTs and DWNTs with no evidence of carbon nanofibres or multi-walled carbon nanotubes on the co-calcination catalyst. Furthermore, I D /I G ratios obtained from Raman spectra were all below 0.1, except for one sample, showing the good quality of the products.

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Section: Resultsmentioning

confidence: 99%

Synthesis of High-Quality Single- and Double-Walled Carbon Nanotubes on Fe/MgO Catalysts

Kashi

Aghababazadeh

Arabi

et al. 2016

Nanomaterials and Nanotechnology

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“…The spectra were fitted with quadrupolesplitting distributions (QSD) assuming a linear correlation between the isomer shift and quadrupole splitting, which will not be discussed here, similar spectra having been extensively discussed elsewhere. 66 A Mössbauer spectroscopy study of similar specimens revealed that there is no interaction between iron-and molybdenum species 34 and comparing with the data obtained for a γ-(Al/Fe) 2 O 3 solid solution 67 could indicate that the present doublet represents Fe 3+ ions distributed among the tetrahedral and octahedral lattice sites of γ-Al 2 O 3 , a defective 9 spinel structure, thus revealing the formation of a γ-(Al/Fe) 2 O 3 solid solution. More specific details about the Fe 3+ -cation distribution in the spinel structure cannot be concluded from the present spectra.…”

Section: Resultsmentioning

confidence: 99%

“…The Fe/Mo molar ratio was fixed to 5 for all samples. The addition of different amounts of molybdenum to the Fe−Al 2 O 3 system was investigated in an earlier study, 34 which showed that the addition of a small amount of molybdenum first favors the formation of DWCNTs over that of SWCNTs and, second, activates smaller nanoparticles, thus producing smaller-diameter CNTs. Each "as-prepared" powder was divided into two batches.…”

Section: ■ Introductionmentioning

confidence: 99%

Large-Diameter Single-Wall Carbon Nanotubes Formed Alongside Small-Diameter Double-Walled Carbon Nanotubes

et al. 2015

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Samples containing a majority of either single-wall carbon nanotubes (SWCNTs) or doublewalled carbon nanotubes (DWCNTs) are prepared in the same catalytic chemical vapor deposition conditions but using slightly different catalytic materials, based on alumina impregnated with iron and molybdenum salts.There is a sharp SWCNTs-to-DWCNTs transition. By contrast to the usual findings, the selectivity is not correlated to the size of the iron-based catalyst nanoparticles, nor does the transition occur upon a decreasing carbon/catalyst ratio. The result is attributed to the increasing MoO 3 concentration inducing modifications of the gas atmosphere, such as the formation of more reactive C 2 species through C 2 H 4 dissociation, which thus favors the nucleation and growth of a DWCNT. In the DWCNT sample, the average diameter of the SWCNTs is higher than the average outer diameter of the DWCNTs, which is uncommon as many authors stress that SWCNTs show a lower diameter than DWCNTs. The study could provide guidelines for the synthesis of very small diameter DWCNTs.

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“…For F (Figure 5a), the proportion of single-walled carbon nanotubes is close to 70%, but for FM (Figure 5b), it is much lower (close to 50%), whereas the proportion of double-walled carbon nanotubes has increased to 40%, in agreement with earlier results. 23 17,28 where this proximity resulted in a higher selectivity toward single-walled carbon nanotubes. It is also noteworthy that, for a given sample, the average inner diameter of the double-walled carbon nanotubes is equal to or lower than the average diameter of the single-walled carbon nanotubes, supporting the yarmulke mechanism, 35,36 a basegrowth mechanism according to which the second nanotubes' cap is formed underneath the first one during the nucleation stage that precedes the simultaneous growth of the two walls.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Chemical Vapor Deposition Synthesis of Double-Walled and Few-Walled Carbon Nanotubes by Using a MoO₃-Supported Conditioning Catalyst to Control the Formation of Iron Catalytic Particles within an α-Al_1.8Fe_0.2O₃ Self-Supported Foam

et al. 2010

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8 Fe 0.2 O 3 -MoO 3 self-supported foams are used as catalytic materials for the synthesis of carbon nanotubes by catalytic chemical vapor deposition. A MoO 3 -supported conditioning catalyst placed upstream in the reactor is more efficient than MoO 3 present within the catalytic material in producing doublewalled and few-walled carbon nanotubes with fewer defects. It is shown that the corresponding modifications of the gas atmosphere (presence of H 2 O formed by the H 2 reduction of MoO 3 and, therefore, lower H 2 and CH 4 concentrations) allow one to limit more efficiently the release of the Fe catalyst from the oxide solidsolution foam, which results in the formation of fewer Fe nanoparticles, which, therefore, are less prone to undesirable growth. Thus, a MoO 3 -induced "solid-state" effect is demonstrated within the catalytic material without molybdenum species being themselves present within this material. This could lead to simplifications in the design of catalytic materials.

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CCVD Synthesis of Single- And Double-Walled Carbon Nanotubes: Influence of the Addition of Molybdenum to Fe−Al₂O₃ Self-Supported Foams

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 8 publications

References 32 publications

Synthesis of High-Quality Single- and Double-Walled Carbon Nanotubes on Fe/MgO Catalysts

Synthesis of High-Quality Single- and Double-Walled Carbon Nanotubes on Fe/MgO Catalysts

Large-Diameter Single-Wall Carbon Nanotubes Formed Alongside Small-Diameter Double-Walled Carbon Nanotubes

Catalytic Chemical Vapor Deposition Synthesis of Double-Walled and Few-Walled Carbon Nanotubes by Using a MoO₃-Supported Conditioning Catalyst to Control the Formation of Iron Catalytic Particles within an α-Al_1.8Fe_0.2O₃ Self-Supported Foam

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CCVD Synthesis of Single- And Double-Walled Carbon Nanotubes: Influence of the Addition of Molybdenum to Fe−Al2O3 Self-Supported Foams

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 8 publications

References 32 publications

Synthesis of High-Quality Single- and Double-Walled Carbon Nanotubes on Fe/MgO Catalysts

Synthesis of High-Quality Single- and Double-Walled Carbon Nanotubes on Fe/MgO Catalysts

Large-Diameter Single-Wall Carbon Nanotubes Formed Alongside Small-Diameter Double-Walled Carbon Nanotubes

Catalytic Chemical Vapor Deposition Synthesis of Double-Walled and Few-Walled Carbon Nanotubes by Using a MoO3-Supported Conditioning Catalyst to Control the Formation of Iron Catalytic Particles within an α-Al1.8Fe0.2O3 Self-Supported Foam

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CCVD Synthesis of Single- And Double-Walled Carbon Nanotubes: Influence of the Addition of Molybdenum to Fe−Al₂O₃ Self-Supported Foams

Catalytic Chemical Vapor Deposition Synthesis of Double-Walled and Few-Walled Carbon Nanotubes by Using a MoO₃-Supported Conditioning Catalyst to Control the Formation of Iron Catalytic Particles within an α-Al_1.8Fe_0.2O₃ Self-Supported Foam