The Influence of Catalyst's Oxidation Degree on Carbon Nanotube Growth as a Substrate-Independent Parameter

Arcos, Teresa de los; Oelhafen, P.; Thommen, V.; Mathys, Daniel

doi:10.1021/jp074928q

Cited by 23 publications

(19 citation statements)

References 14 publications

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“…As with the open CNT ends observed with the peeled samples we never observe the end of CNT at the catalyst particle but instead the end of the CNT lies at the support. Similar observations have been observed previously also [11,12]. Indeed, the consistent observation of elongated catalyst particles in the CNT core at an open end (base) or further up the tube, suggest growth occurs on the substrate itself.…”

Section: Resultssupporting

confidence: 89%

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On the graphitisation role of oxide supports in carbon nanotube CVD synthesis

Rümmeli

Schäffel

Arcos

et al. 2008

Physica Status Solidi (b)

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In this contribution we present various data from CNT grown from supported catalysts. The observed data are in agreement with the catalyst volume to surface area model developed for floating catalysts and which predicts a direct CNT diameter and number of wall dependence on the catalyst size. Further, our studies point to the root of a CNT lying at the support rather than the catalyst. Additional supporting studies point to oxygen playing a critical role in the growth of CNT, viz. the CNT can grow from an oxide support rather than the catalyst. In this scenario the catalysts role is twofold; to precipitate carbon from the catalyst–carbon eutectic upon supersaturation and thus form the embryonic caps and to form circular defect sites at its circumference on the oxide support. These circular defect sites enable continued CNT growth directly from the support. Our findings point to catalytic processes very reminiscent of many other heterogeneous catalytic processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultssupporting

confidence: 89%

“…Figure 4 shows comparative SEM images from two equivalently processed nano-engineered Fe particles on Al 2 O 3 and TiN supports respectively. Further studies are required to better understand this difference, however, the result is in keeping with various other studies suggesting oxygen plays a critical role in CNT synthesis [2,10,11,16].…”

Section: Resultssupporting

confidence: 78%

On the graphitisation role of oxide supports in carbon nanotube CVD synthesis

Rümmeli

Schäffel

Arcos

et al. 2008

Physica Status Solidi (b)

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“…52 As the pretreatment time increases, the Fe 3 O 4 Raman peaks became more intense, indicating better crystallization for a longer time. Dai et al 53 proposed that both Fe and FeO can act as catalysts for the growth of CNTs but FeO is the more active catalyst, which is supported by Arcos et al 56,57 As reported in several previous studies, 24,48 however, native oxide was not reduced completely to Fe even in a reducing environment (He/H 2 gas mixture) under our experimental conditions. 4.…”

Section: A Effect Of H 2 Pretreatment On Morphology Of Catalystssupporting

confidence: 84%

Effect of hydrogen pretreatment on the spin-capability of a multiwalled carbon nanotube forest

Jung¹,

Han²,

Overzet³

et al. 2013

Journal of Vacuum Science & Technology B, Nanotechnology an

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Articles you may be interested inEffect of hydrogen plasma irradiation of catalyst films on growth of carbon nanotubes filled with iron nanowires J. Vac. Sci. Technol. A 32, 02B102 (2014); 10.1116/1.4827822Effect of purity, edge length, and growth area on field emission of multi-walled carbon nanotube emitter arrays Thickness effect of nanosized thin-film iron dot on growth of multiwall carbon nanotubesThe authors report the effect of hydrogen (H 2 ) pretreatment on the spin capability of vertically aligned multiwalled carbon nanotubes (MWCNTs) grown on an iron (Fe) catalyst by using a chemical vapor deposition system. Variations in H 2 pretreatment time had significant effects on the distribution, morphology, diameter, and height of MWCNTs. A longer H 2 pretreatment time to the Fe film increased the number of large Fe particles as well as crystallization of Fe 3 O 4 phase. As a result, the areal density of carbon nanotubes (CNTs) was largely reduced, whereas the mean CNT diameter slightly increased. This worsened the alignment of the CNTs and reduced the spin-capability of MWCNTs.

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“…However, the applications of metal films as catalysts for the synthesis of CNTs reveal the necessity to study their oxidation after exposure to air and subsequent activation for the CNT growth by calcination in different gas environments or by interaction with different plasmas. It was demonstrated by Arcos et al [86] that oxidized Fe NPs on Al 2 O 3 buffer layer exhibited much better catalytic activity than metallic, although the metallic particles are efficient catalysts on other substrates, such as TiN or TiO 2 .…”

Section: Catalysts In Chemical Vapor Deposition Of Carbon Nanotubesmentioning

confidence: 99%

Synthesis of carbon nanotubes by plasma-enhanced chemical vapor deposition in an atmospheric-pressure microwave torch

Zajı́čková

Jašek

Eliáš

et al. 2010

Pure and Applied Chemistry

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Abstract:There are many different techniques for the synthesis of carbon nanotubes (CNTs), and plasma technologies experience a significant competitor in thermal chemical vapor deposition (CVD) processes. A particular process is, therefore, selected according to the specific requirements of an application, which clearly differ for the development of composites as compared to nanoelectronics, field emission, displays, sensors, and the like. This paper discusses the method for the synthesis of CNTs using an atmospheric-pressure microwave (MW) torch. It was successfully applied in the fast deposition of multiwalled nanotubes (MWNTs) on a substrate without the necessity of any vacuum or heating equipment. Dense straight-standing nanotubes were prepared on Si substrates with and also without barrier SiO x layer. Therefore, it was possible to produce CNTs directly on conductive Si and to use them as an electron-emitting electrode of the gas pressure sensor. The CNTs grown in MW torch were also used to create a gas sensor based on the changes of electrical resistance measured between two planar electrodes connected by the CNTs.

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The Influence of Catalyst's Oxidation Degree on Carbon Nanotube Growth as a Substrate-Independent Parameter

Cited by 23 publications

References 14 publications

On the graphitisation role of oxide supports in carbon nanotube CVD synthesis

On the graphitisation role of oxide supports in carbon nanotube CVD synthesis

Effect of hydrogen pretreatment on the spin-capability of a multiwalled carbon nanotube forest

Synthesis of carbon nanotubes by plasma-enhanced chemical vapor deposition in an atmospheric-pressure microwave torch

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