Controlled production of single-wall carbon nanotubes by catalytic decomposition of CO on bimetallic Co–Mo catalysts

Kitiyanan, Boonyarach; Alvarez, Walter E.; Harwell, Jeffrey H.; Resasco, Daniel E.

doi:10.1016/s0009-2614(99)01379-2

Cited by 616 publications

(424 citation statements)

References 16 publications

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“…In 2000, a new method utilising cobalt and molybdenum catalysts and CO as a carbon source gas (CoMoCAT) was developed by Kitiyanan et al [122]. Since very first experiments, the CoMoCAT method appeared to be promising and fruitful, allowing to produce about 0.25 g SWNT/g catalyst in a couple of hours.…”

Section: Cobalt and Molybdenum (Como) Cat Processmentioning

confidence: 99%

Carbon nanotubes for ultrafast fibre lasers

et al. 2016

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Carbon nanotubes (CNTs) possess both remarkable optical properties and high potential for integration in various photonic devices. We overview, here, recent progress in CNT applications in fibre optics putting particular emphasis on fibre lasers. We discuss fabrication and characterisation of different CNTs, development of CNTbased saturable absorbers (CNT-SA), their integration and operation in fibre laser cavities putting emphasis on stateof-the-art fibre lasers, mode locked using CNT-SA. We discuss new design concepts of high-performance ultrafast operation fibre lasers covering ytterbium (Yb), bismuth (Bi), erbium (Er), thulium (Tm) and holmium (Ho)-doped fibre lasers.

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Section: Cobalt and Molybdenum (Como) Cat Processmentioning

confidence: 99%

Carbon nanotubes for ultrafast fibre lasers

et al. 2016

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“…21 The catalysts used for CVD are usually metal nanoparticles (i.e., Fe, Ni, Co, or Mo). [22][23][24] Growth temperatures usually range between 500 and 1000 ºC, 2 but lower temperatures have been used to grow SWNTs on flexible or glass substrates. 25,26 Synthesis times vary from a few minutes to several hours, and SWNT growth ceases when the feedstock is discontinued or the catalyst becomes poisoned by amorphous carbon.…”

Section: Synthesis Of Swntsmentioning

confidence: 99%

“…25,26 Synthesis times vary from a few minutes to several hours, and SWNT growth ceases when the feedstock is discontinued or the catalyst becomes poisoned by amorphous carbon. 27,28 The catalyst lifetime can be extended by using carbon sources containing oxygen 18,24,28 or by introducing water, oxygen, or hydrogen gas during the synthesis. 29,30 Chemical vapor deposition offers a number of advantages over the arc discharge and laser vaporization methods for SWNT synthesis.…”

Section: Synthesis Of Swntsmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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“…The higher the concentration of semiconducting tubes, the higher the probability of them being adjacent, the higher the chance of EET-induced emission. Thus, the strongest peaks will appear around eh ii transitions of semiconducting tubes with highest concentration, such as (6, 5), (7,5), (8,4) in our CoMoCAT solutions [16,17]. Fig.3 compares the absorption of the as-prepared solution with its photoluminescence emission and excitation spectra.…”

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confidence: 95%

“…We measure absorption on CoMoCAT SWNT(South West Nanotechnologies) [16] suspensions in D 2 O with sodium dodecylbenzene sulfonate (SDBS) surfactant [2], using a Perkin-Elmer 950 spectrometer. A JY Fluorolog-3 is used for Photoluminescence Excitation (PLE).…”

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confidence: 99%

Photoluminescence Spectroscopy of Carbon Nanotube Bundles: Evidence for Exciton Energy Transfer

et al. 2007

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Photoluminescence is commonly used to identify the electronic structure of individual nanotubes. But, nanotubes naturally occur in bundles. Thus, we investigate photoluminescence of nanotube bundles. We show that their complex spectra are simply explained by exciton energy transfer between adjacent tubes, whereby excitation of large gap tubes induces emission from smaller gap ones via Förster interaction between excitons. The consequent relaxation rate is faster than nonradiative recombination, leading to enhanced photoluminescence of acceptor tubes. This fingerprints bundles with different compositions and opens opportunities to optimize them for opto-electronics.

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Controlled production of single-wall carbon nanotubes by catalytic decomposition of CO on bimetallic Co–Mo catalysts

Cited by 616 publications

References 16 publications

Carbon nanotubes for ultrafast fibre lasers

Carbon nanotubes for ultrafast fibre lasers

Photophysics of Individual Single-Walled Carbon Nanotubes

Photoluminescence Spectroscopy of Carbon Nanotube Bundles: Evidence for Exciton Energy Transfer

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