In situ Observations of Catalyst Dynamics during Surface-Bound Carbon Nanotube Nucleation

Hofmann, Stephan; Sharma, Renu; Ducati, Caterina; Du, Gaohui; Mattevi, Cecilia; Cepek, Cinzia; Cantoro, Mirco; Pisana, Simone; Parvez, A.; Cervantes‐Sodi, Felipe; Ferrari, Andrea C.; Dunin-Borkowski, Rafal E.; Lizzit, Silvano; Petaccia, L.; Goldoni, A.; Robertson, John

doi:10.1021/nl0624824

Cited by 693 publications

(715 citation statements)

References 32 publications

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“…Because CH 4 cannot easily be dissociated at the catalyst surface, this suggests that the carbon source for CNT formation is rather limited, which could correspond to conditions favorable for SWCNT growth, as is indeed observed in literature [20,21]. In all cases investigated, the density of atomic carbon in the plasma is found to be very low; hence the C-supply for the CNT/CNF growth needs to come from decomposition of hydrocarbon species at the catalyst surface itself, as is also generally stated in literature [55]. The detailed behavior of the hydrocarbon species at the catalyst surface is not yet taken into account in our model.…”

Section: Discussionsupporting

confidence: 74%

“…In general, we can see that atomic carbon is hardly formed in the plasma, for the four gas mixtures under study at two different gas pressures. Therefore we can conclude that the carbon sources for CNT/CNF growth mainly arise from decomposition of hydrocarbon molecules on the catalyst surface, as is also stated in [55].…”

Section: Plasma Chemistry In the Different Gas Mixturessupporting

confidence: 69%

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Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Mao¹,

Bogaerts²

2010

J. Phys. D: Appl. Phys.

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To cite this version:M Mao, A Bogaerts. Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures. Journal of Physics D: Applied Physics, IOP Publishing, 2010, 43 (20) Abstract. A hybrid model, called the Hybrid Plasma Equipment Model (HPEM) was used to study an inductively coupled plasma in gas mixtures of H 2 or NH 3 with CH 4 or C 2 H 2 used for the synthesis of carbon nanotubes or carbon nanofibers (CNTs/CNFs). The plasma properties are discussed for the different gas mixture at low and moderate pressure, and the growth precursors for CNTs/CNFs are analyzed. It is found that C 2 H 2 , C 2 H 4 , and C 2 H 6 are the predominant molecules in CH 4 containing plasmas beside the feedstock gas, and serve as carbon sources for CNT/CNF formation. On the other hand, long chain hydrocarbons are observed in C 2 H 2 containing plasmas. Furthermore, the background gases CH 4 and C 2 H 2 show a different decomposition rate with H 2 or NH 3 addition at moderate pressures.

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Section: Discussionsupporting

confidence: 74%

Section: Plasma Chemistry In the Different Gas Mixturessupporting

confidence: 69%

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Mao¹,

Bogaerts²

2010

J. Phys. D: Appl. Phys.

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“…Our work shows this earlier hypothesis is incorrect. For the SWNT network, we have no obvious edge-plane sites, and the ends are most likely to be closed (38). We see high and similar activity across different sites in SWNT networks.…”

Section: Resultsmentioning

confidence: 74%

“…1B. Each SWNT is grown from a single catalytic nanoparticle that is embedded at one end of the SWNT (38,39). The density of SWNTs was above the metallic percolation threshold (40), so after establishing macroscopic electrical contacts to the network, the sample was ready to be used without any need of postprocessing cleaning steps.…”

Section: Resultsmentioning

confidence: 99%

Quantitative nanoscale visualization of heterogeneous electron transfer rates in 2D carbon nanotube networks

Güell¹,

Ebejer²,

Snowden³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

113

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Carbon nanotubes have attracted considerable interest for electrochemical, electrocatalytic, and sensing applications, yet there remains uncertainty concerning the intrinsic electrochemical (EC) activity. In this study, we use scanning electrochemical cell microscopy (SECCM) to determine local heterogeneous electron transfer (HET) kinetics in a random 2D network of single-walled carbon nanotubes (SWNTs) on an Si∕SiO 2 substrate. The high spatial resolution of SECCM, which employs a mobile nanoscale EC cell as a probe for imaging, enables us to sample the responses of individual portions of a wide range of SWNTs within this complex arrangement. Using two redox processes, the oxidation of ferrocenylmethyl trimethylammonium and the reduction of ruthenium (III) hexaamine, we have obtained conclusive evidence for the high intrinsic EC activity of the sidewalls of the large majority of SWNTs in networks. Moreover, we show that the ends of SWNTs and the points where two SWNTs cross do not show appreciably different HET kinetics relative to the sidewall. Using finite element method modeling, we deduce standard rate constants for the two redox couples and demonstrate that HET based solely on characteristic defects in the SWNT side wall is highly unlikely. This is further confirmed by the analysis of individual line profiles taken as the SECCM probe scans over an SWNT. More generally, the studies herein demonstrate SECCM to be a powerful and versatile method for activity mapping of complex electrode materials under conditions of high mass transport, where kinetic assignments can be made with confidence.W ithin the family of nanostructured materials, carbon nanotubes (CNTs) have attracted particular attention because they are readily synthesised at low cost, have exceptional electronic properties, exhibit chemical and mechanical stability, and are amenable to a wide range of simple chemical functionalization routes (1-3). These characteristics have led to CNTs being considered ideal substrates for electronics (4), sensing systems (5, 6), electrocatalytic supports (7), and batteries (8). Furthermore, the different configurations in which CNTs can be arranged broaden their versatility and allow custom design of devices for specific applications. Individual single-walled carbon nanotubes (SWNTs) (9), 2D networks (10-12), and 3D nanostructures (13) have all been employed successfully.Understanding heterogeneous electron transfer (HET) at CNTs is of considerable importance, due to the wide range of electroanalytical and electrocatalytic systems based on CNTs (14-17), and also because electrochemistry provides an attractive route to functionalize and tailor the properties of . Probing HET in 1D electrode materials is interesting fundamentally, given their inherent electronic structure and properties (21,22). However, as we highlight herein, despite many studies aimed at characterizing HET at CNTs, substantial questions remain unanswered, such as the location and rate of HET.A popular approach for studying electrochemistry at CNT...

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“…For synthesizing CNMs, typically nanometer sized metal particles are required to enable hydrocarbon decomposition at a lower temperature than the spontaneous decomposition temperature of the hydrocarbon [19]- [22]. Most commonly used metals are iron, cobalt, nickel because of two main reasons: i) high solubility of carbon in these metals at high temperatures and ii) high carbon diffusion rate in these metals.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterisation of Carbon Nano Materials from Plant Derivative

Viswanathan¹,

Bhowmik²,

Sharon³

2014

IJMMM

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Abstract-Latex of Calotropis was used as precursor for synthesis of Carbon Nano material (CNM) by chemical vapour deposition (CVD) / pyrolysis process. Impact of different carrier gases (Hydrogen, Argon) and catalyst (Nickel, Cobalt, Iron) on morphology of CNM was assessed. It was found that Pyrolysis in presence of Hydrogen produced more defined Carbon Nano beads (10 nm to 900 nm) than with Argon which produced agglomerated clusters of spherical nano particles. So far as catalysts are concerned, Nickel gave better Carbon nano beads.Index Terms-Carbon nano material, carrier gas, latex of calotropis, metal nanocatalyst, pyrolysis.

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In situ Observations of Catalyst Dynamics during Surface-Bound Carbon Nanotube Nucleation

Cited by 693 publications

References 32 publications

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma enhanced CVD system: the effect of different gas mixtures

Quantitative nanoscale visualization of heterogeneous electron transfer rates in 2D carbon nanotube networks

Synthesis and Characterisation of Carbon Nano Materials from Plant Derivative

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