Efficient route to large arrays of CNx nanofibers by pyrolysis of ferrocene/melamine mixtures

Terrones, Mauricio; Terrones, Humberto; Grobert, Nicole; Hsu, Wen Kuang; Zhu, Yan; Hare, Jonathon; Kroto, Harold W.; Walton, D. R. M.; Kohler-Redlich, Ph.; Rühle, M.; Zhang, J. P.; Cheetham, Anthony K.

doi:10.1063/1.125498

Cited by 247 publications

(171 citation statements)

References 21 publications

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“…Their low-dimensional structure does not provide an energetically favorable environment for most impurity atoms. Fortunately, there are two promising exceptions, boron [2] and nitrogen [3], both of which seem able to reside within the carbon lattice.…”

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Nonlinear Behavior in the Thermopower of Doped Carbon Nanotubes Due to Strong, Localized States

et al. 2003

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The temperature dependent thermoelectric power (TEP) of boron and nitrogen doped multiwalled carbon nanotube mats has been measured showing that such dopants can be used to modify the majority conduction from p-type to n-type. The TEP of boron doped nanotubes is positive, indicating hole-like carriers. In contrast, the nitrogen doped material exhibits negative TEP over the same temperature range, suggesting electron-like conduction. Therefore, the TEP distinct nonlinearites are primarily due to the formation of donor and acceptor states in the B-and N-doped materials. The sharply varying density of states used in our model can be directly correlated to the scanning tunneling spectroscopy studies of these materials.PACS numbers: 65.80+n, 61.46+w, 73.63.Fg, 81.07.De Interest in the electrical transport properties of both single-walled (SWNT) and multi-walled (MWNT) carbon nanotubes stems primarily from anticipated applications of these low-dimensional materials in nanoelectronics [1]. One expects metallic conduits along with heterojunctions, formed from nanomaterials with different carriers (electrons vs. holes), to be necessary. These would play an analogous role to 'bulk' doped Si devices and metal interconnect lines. However, the direct substitutional doping of carbon nanotubes has proven to be quite difficult. Their low-dimensional structure does not provide an energetically favorable environment for most impurity atoms. Fortunately, there are two promising exceptions, boron [2] and nitrogen [3], both of which seem able to reside within the carbon lattice.In this Letter we report on the effect of donor and acceptor states on the thermoelectric power (TEP) of boron doped and nitrogen doped nanotube mats. TEP is an important and sensitive test of the carrier sign of any material. Because the TEP is a zero current transport coefficient, it can probe the intrinsic conduction properties of individual nanotubes while being less influenced by randomly entangled morphologies and imperfections of the measured mats as compared to standard conductivity measurements [4]. For example, intrinsic-metallic properties were well demonstrated with the TEP of conducting polymer films exhibiting randomly entangled fibrillar morphologies. However, in these systems, the electrical conductivity always showed a semiconducting temperature dependence due to interfibrillar junction resistances [5]. Generally, SWNT and MWNT randomly orientated mats show a positive and moderately large thermoelectric power (TEP) over the temperature range of 0 to 300 K, with temperature dependencies that approach zero as T 0 →0 [6]. However, earlier studies have shown that "doping" the SWNT mats by intercalating alkali metals into the nanotube bundles could give rise to significantly different thermoelectric properties [7]. Likewise, more recent work has demonstrated an extreme sensitivity of the thermoelectric properties of SWNT mats to oxygen contamination (or doping) [8]. In fact, this exposure to various atmospheres has become a central issue in und...

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Nonlinear Behavior in the Thermopower of Doped Carbon Nanotubes Due to Strong, Localized States

et al. 2003

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“…This technique has been recently described [17,18]. The produced material consists of carpet-like structures containing highly oriented nanotubes/nanofibres of uniform diameter and length.…”

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“…As will be seen later, we attribute such holes to lattice discontinuities with nitrogen decoration. High resolution electron energy loss spectroscopy (HREELS) studies of these and similar materials reveal the incorporation of N within the graphene lattice at levels between 2 % and 10 % (atom percent) [17][18][19][20][21].…”

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Identification of Electron Donor States in N-Doped Carbon Nanotubes

et al. 2001

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Nitrogen doped carbon nanotubes have been synthesized using pyrolysis and characterized by Scanning Tunneling Spectroscopy and transmission electron microscopy. The doped nanotubes are all metallic and exhibit strong electron donor states near the Fermi level. Using tight-binding and ab initio calculations, we observe that pyridine-like N structures are responsible for the metallic behavior and the prominent features near the Fermi level. These electron rich structures are the first example of n-type nanotubes, which could pave the way to real molecular hetero-junction devices.

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“…The diameters of the nanotubes are varying in between 30 and 60 nm. It has been suggested that bamboo-shaped morphologies arise from the incorporation of pyridine-like N atoms within the carbon framework [30][31][32]. Also, no encapsulated metal particle was found inside the nanotubes.…”

Section: C-n Nanotubesmentioning

confidence: 99%

Synthesis of carbon and carbon–nitrogen nanotubes using green precursor: jatropha-derived biodiesel

Kumar

Yadav

Awasthi³

et al. 2012

Journal of Experimental Nanoscience

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The jatropha-derived biodiesel, a green precursor was found to be a new and promising precursor for the synthesis of carbon nanotubes (CNTs) and carbonnitrogen (C-N) nanotubes. The CNTs and C-N nanotubes have been synthesised by spray pyrolysis of biodiesel with ferrocene and ferrocene-acetonitrile, respectively, at elevated temperature under an argon atmosphere. The typical length and diameter of as-grown CNTs are 20 mm and 20-50 nm, respectively. The C-N nanotubes are found in bundles with effective length of 30 mm and diameter ranging between 30 and 60 nm with bamboo-shaped morphology. The as-grown CNTs and C-N nanotubes were characterised through scanning and transmission electron microscopes, X-ray photoelectron, Raman and Fourier transform infrared spectroscopic techniques. These investigations revealed that the nanotubes synthesised by jatropha-derived biodiesel are clean from carbonaceous impurities and the bamboo compartment formations in C-N nanotubes are due to nitrogen incorporation. The nitrogen concentration in C-N nanotubes decreases with the increase in synthesis temperature.

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Efficient route to large arrays of CNx nanofibers by pyrolysis of ferrocene/melamine mixtures

Cited by 247 publications

References 21 publications

Nonlinear Behavior in the Thermopower of Doped Carbon Nanotubes Due to Strong, Localized States

Nonlinear Behavior in the Thermopower of Doped Carbon Nanotubes Due to Strong, Localized States

Identification of Electron Donor States in N-Doped Carbon Nanotubes

Synthesis of carbon and carbon–nitrogen nanotubes using green precursor: jatropha-derived biodiesel

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