An original growth mode of MWCNTs on alumina supported iron catalysts

Philippe, Régis; Caussat, Brigitte; Falqui, Andrea; Kihn, Y.; Kalck, Philippe; Bordère, Serge; Plee, D.; Gaillard, Patrice; Bernard, Daniel; Serp, Philippe

doi:10.1016/j.jcat.2009.02.027

Cited by 58 publications

(37 citation statements)

References 44 publications

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“…However, challenges remain with fabrication of technical CNT-based catalysts mainly due to the shaping difficulties. Successful growth of CNTs on silica spheres, 50 alumina particles, 51 and inert SiC substrates 52 His research activities focus on the fundamental study of catalysis, including development of new catalysts and novel catalytic processes related to energy. Currently, his attention is focused on "nanocatalysis" with emphasis on the development of science and techniques to assemble and stabilize nanostructured particles using porous materials and carbon nanotubes.…”

Section: Conclusion and Prospectsmentioning

confidence: 99%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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T he unique tubular morphology of carbon nanotubes (CNTs) has triggered wide research interest. These structures can be used as nanoreactors and to create novel composites through the encapsulation of guest materials in their well-defined channels. The rigid nanotubes restrict the size of the encapsulated materials down to the nanometer and even the subnanometer scale. In addition, interactions may develop between the encapsulated molecules and nanomaterials and the CNT surfaces. The curvature of CNT walls causes the π electron density of the graphene layers to shift from the concave inner to the convex outer surface, which results in an electric potential difference. As a result, the molecules and nanomaterials on the exterior walls of CNTs likely display different properties and chemical reactivities from those confined within CNTs. Catalysis that utilizes the interior surface of CNTs was only explored recently. An increasing number of studies have demonstrated that confining metal or metal oxide nanoparticles inside CNTs often leads to a different catalytic activity with respect to the same metals deposited on the CNT exterior surface. Furthermore, this inside and outside activity difference varies based on the metals used and the reactions catalyzed.In this Account, we describe the efforts toward understanding the fundamental effects of confining metal nanoparticles inside the CNT channels. This research may provide a novel approach to modulate their catalytic performance and promote rational design of catalysts. To achieve this, we have developed strategies for homogeneous dispersion of nanoparticles inside nanotubes. Because researchers have previously demonstrated the insertion of nanoparticles within larger nanotubes, we focused specifically on multiwalled carbon nanotubes (MWCNTs) with an inner diameter (i.d.) smaller than 10 nm and double-walled carbon nanotubes (DWCNTs) with 1.0À1.5 nm i.d. The results show that CNTs with well-defined morphology and unique electronic structure of CNTs provide an intriguing confinement environment for catalysis.

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Section: Conclusion and Prospectsmentioning

confidence: 99%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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“…Iron carbide (Fe 3 C) is in fact often observed by TEM and XRD after growth. [114] However, most groups reported that Fe 3 C does not catalyze the growth of CNTs. Yoshida et al managed to grow MWCNTs on fresh Fe 3 C, but only in an ETEM.…”

Section: The Vapor-liquid-solid Mechanism and Its Validitymentioning

confidence: 99%

“…Philippe et al adapted the knowledge gained on aligned CNTs arrays to design a scalable version for which the growth could be carried out in a fluidized bed reactor. [114] Their catalyst consisted of an iron film deposited on boehmite grains by CVD of ferrocene. Although the iron film was relatively thick (1 mm), they obtained relatively narrow (ca.…”

Section: Wwwchemsuschemorgmentioning

confidence: 99%

Recent Progress on the Growth Mechanism of Carbon Nanotubes: A Review

2011

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Tremendous progress has been achieved during the past 20 years on not only improving the yields of carbon nanotubes and move progressively towards their mass production, but also on gaining a profound fundamental understanding of the nucleation and the growth processes. Parameters that influence the yield but also the quality (e.g., microstructure, homogeneity within a batch) are better understood. The influence of the carbon precursor, the reaction conditions, the presence of a catalyst, the chemical and physical status of the latter, and other factors have been extensively studied. The purpose of the present Review is not to list all the experiments reported in the literature, but rather to identify trends and provide a comprehensive summary on the role of selected parameters. The role of the catalyst occupies a central place in this Review as a careful control of the metal particle size, particle dispersion on the support, the metastable phase formed under reaction conditions, its possible reconstruction, and faceting strongly influence the diameter of the carbon nanotubes, their structure (number of walls, graphene sheet orientation, chirality), their alignment, and the yield. The identified trends will be compared with recent observations on the growth of graphene. Recent results on metal-free catalysts will be analyzed from a different perspective.

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“…5). They could be related to iron carbide (Fe 3 C) since iron NPs should be saturated with carbon atoms as they act as the catalyst for the MWCNT growth [43]. After deposition, three new peaks appear at 2θ = 43.3°, 50.4°and 74.0°for all the runs.…”

Section: Xrd Resultsmentioning

confidence: 99%

Fluidized bed chemical vapor deposition of copper nanoparticles on multi-walled carbon nanotubes

Lassègue

Noé

Monthioux

et al. 2017

Surface and Coatings Technology

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. A B S T R A C TMulti-walled carbon nanotubes tangled in easy-to-fluidize porous balls have been decorated by pure copper nanoparticles using a pre-industrial fluidized bed chemical vapor deposition process. Copper (II) acetylacetonate Cu(acac) 2 was used as precursor. The low precursor volatility led to low deposition rates, responsible for a nonuniformity of the deposit both on the MWCNT balls and from the outer part to the center of the balls. An oxidative pre-treatment of the MWCNTs allowed to increase slightly the deposit weight and uniformity, by creating new nucleation sites on the nanotube surface. It also allowed decreasing the size of Cu nanoparticles by a factor of ten. A decrease of the deposition temperature increased more markedly the deposit weight, by probably favoring the formation of gaseous reactive intermediate species more reactive on the oxidized nanotube surface. A more efficient precursor delivery system would allow reaching higher deposition rates and much more uniform deposits, making possible an industrial production of metallized carbon nanotubes.

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An original growth mode of MWCNTs on alumina supported iron catalysts

Cited by 58 publications

References 44 publications

The Effects of Confinement inside Carbon Nanotubes on Catalysis

The Effects of Confinement inside Carbon Nanotubes on Catalysis

Recent Progress on the Growth Mechanism of Carbon Nanotubes: A Review

Fluidized bed chemical vapor deposition of copper nanoparticles on multi-walled carbon nanotubes

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