The Phase of Iron Catalyst Nanoparticles during Carbon Nanotube Growth

Wirth, Christoph; Bayer, Bernhard C.; Gamalski, Andrew D.; Esconjauregui, Santiago; Weatherup, Robert S.; Ducati, Caterina; Baehtz, Carsten; Robertson, John; Hofmann, Stephan

doi:10.1021/cm301402g

Cited by 184 publications

(183 citation statements)

References 46 publications

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“…SWCNT growth from solid catalysts has been confirmed as well as nanowire growth [22,23]. The active forms of Fe catalyst have been reported to be liquid phase, solid Fe metal or Fe carbide depending on the growth temperature and the carbon contamination level [22,24,25]. The Ni catalyst is reported to be in the solid state up to 1200 °C [24].…”

Section: Swcnt Growth Mechanism From Gold Nanoparticlesmentioning

confidence: 86%

Gold Nanoparticles as the Catalyst of Single-Walled Carbon Nanotube Synthesis

Homma

2014

Catalysts

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Gold nanoparticles have been proven to act as efficient catalysts for chemical reactions, such as oxidation and hydrogen production. In this review we focus on a different aspect of the catalysis of gold nanoparticles; single-walled carbon nanotube (SWCNT) synthesis. This is not a traditional meaning of catalytic reaction, but SWCNTs cannot be synthesized without nanoparticles. Previously, gold was considered as unsuitable metal species as the catalyst of SWCNT synthesis. However, gold nanoparticles with diameters smaller than 5 nm were found to effectively produce SWCNTs. We discuss the catalysis of gold and related metals for SWCNT synthesis in comparison with conventional catalysts, such as iron, cobalt, and nickel.

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Section: Swcnt Growth Mechanism From Gold Nanoparticlesmentioning

confidence: 86%

Gold Nanoparticles as the Catalyst of Single-Walled Carbon Nanotube Synthesis

Homma

2014

Catalysts

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“…2−4,8,10−14 More controlled CNT LiCVD requires a detailed understanding of the catalytic growth process and the related laser interactions. Crucial to this, albeit widely neglected in the current literature, are process-specific increases in optical absorption arising from initial reduction of the transition-metal nanoparticle catalysts typically used, 26 such as Fe, and the ever increasing amount of carbon deposited. This can lead to detrimental positive optical feedback, whereby the sample quickly overheats at the center of the laser spot, leading to uncontrolled inhomogeneous growth.…”

Section: ■ Introductionmentioning

confidence: 99%

Co-catalytic Absorption Layers for Controlled Laser-Induced Chemical Vapor Deposition of Carbon Nanotubes

Michaelis

Weatherup

Bayer

et al. 2014

ACS Appl. Mater. Interfaces

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The concept of co-catalytic layer structures for controlled laser-induced chemical vapor deposition of carbon nanotubes is established, in which a thin Ta support layer chemically aids the initial Fe catalyst reduction. This enables a significant reduction in laser power, preventing detrimental positive optical feedback and allowing improved growth control. Systematic study of experimental parameters combined with simple thermostatic modeling establishes general guidelines for the effective design of such catalyst/absorption layer combinations. Local growth of vertically aligned carbon nanotube forests directly on flexible polyimide substrates is demonstrated, opening up new routes for nanodevice design and fabrication.

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“…Papers studying locally structural changes around the catalyst particles either through in-situ TEM or XRD [46][47][48] are focused on the structural changes occurring on the catalyst particles and show the forming graphitic structure, but no quantitative analysis of the carbon structure comparable to Raman spectroscopy has been performed. In addition, literature does not report any quantitative and spatially resolved analysis of carbon structure around catalyst nanoparticles for nanotube growth.…”

Section: Methodsmentioning

confidence: 99%

Structure in nascent carbon nanotubes revealed by spatially resolved Raman spectroscopy

Landois¹,

Pinault²,

Huard³

et al. 2014

Thin Solid Films

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Abstract:The understanding of carbon nanotubes (CNT) growth is crucial for the control of their production. In particular, the identification of structural changes of carbon possibly occurring near the catalyst particle in the very early stages of their formation is of high interest. In this study, samples of nascent CNT obtained during nucleation step and samples of vertically aligned CNT obtained during growth step are analysed by combined spatially resolved Raman spectroscopy and X-Ray diffraction measurements. Spatially resolved Raman spectroscopy reveals that iron-based phases and carbon phases are co-localised at the same position, and indicates that sp 2 carbon nucleates preferentially on iron-based particles during this nucleation step. Depth scan Raman spectroscopy analysis, performed on nascent CNT, highlights that carbon structural organisation is significantly changing from defective graphene layers surrounding the iron-based particles at their base up to multi-walled nanotube structures in the upper part of iron-based particles.

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The Phase of Iron Catalyst Nanoparticles during Carbon Nanotube Growth

Cited by 184 publications

References 46 publications

Gold Nanoparticles as the Catalyst of Single-Walled Carbon Nanotube Synthesis

Gold Nanoparticles as the Catalyst of Single-Walled Carbon Nanotube Synthesis

Co-catalytic Absorption Layers for Controlled Laser-Induced Chemical Vapor Deposition of Carbon Nanotubes

Structure in nascent carbon nanotubes revealed by spatially resolved Raman spectroscopy

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