Growth mechanisms for single-wall carbon nanotubes in a laser-ablation process

Scott, Clayton; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, R. E.

doi:10.1007/s003390100761

Cited by 330 publications

(144 citation statements)

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“…Carbon sources are graphite, or gaseous carbon-bearing compounds such as CO, methane, ethylene, or other hydrocarbons. The vaporized carbon atoms (or clusters) and hot metal catalysts co-condense into gas-phase molten nanoparticles where nanotubes grow (Moisala et al, 2003;Scott et al, 2001). MWCNTs can be produced without metals; however, the presence of a small amount of metal catalyst helps to align the nanotubes.…”

Section: Synthesis Of Carbon Nanotubes and Impurities In Syntheticmentioning

confidence: 99%

A Review of Carbon Nanotube Toxicity and Assessment of Potential Occupational and Environmental Health Risks

Lam

James

McCluskey

et al. 2006

Critical Reviews in Toxicology

1,085

672

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Nanotechnology has emerged at the forefront of science research and technology development. Carbon nanotubes (CNTs) are major building blocks of this new technology. They possess unique electrical, mechanical, and thermal properties, with potential wide applications in the electronics, computer, aerospace, and other industries. CNTs exist in two forms, single-wall (SWCNTs) and multi-wall (MWCNTs). They are manufactured predominately by electrical arc discharge, laser ablation and chemical vapor deposition processes; these processes involve thermally stripping carbon atoms off from carbon-bearing compounds. SWCNT formation requires catalytic metals. There has been a great concern that if CNTs, which are very light, enter the working environment as suspended particulate matter (PM) of respirable sizes, they could pose an occupational inhalation exposure hazard. Very recently, MWCNTs and other carbonaceous nanoparticles in fine (<2.5 µm) PM aggregates have been found in combustion streams of methane, propane, and natural-gas flames of typical stoves; indoor and outdoor fine PM samples were reported to contain significant fractions of MWCNTs. Here we review several rodent studies in which test dusts were administered intratracheally or intrapharyngeally to assess the pulmonary toxicity of manufactured CNTs, and a few in vitro studies to assess biomarkers of toxicity released in CNT-treated skin cell cultures. The results of the rodent studies collectively showed that regardless of the process by which CNTs were synthesized and the types and amounts of metals they contained, CNTs were capable of producing inflammation, epithelioid granulomas (microscopic nodules), fibrosis, and biochemical/toxicological changes in the lungs. Comparative toxicity studies in which mice were given equal weights of test materials showed that SWCNTs were more toxic than quartz, which is considered a serious occupational health hazard if it is chronically inhaled; ultrafine carbon black was shown to produce minimal lung responses. The differences in opinions of the investigators about the potential hazards of exposures to CNTs are discussed here. Presented here are also the possible mechanisms of CNT pathogenesis in the lung and the impact of residual metals and other impurities on the toxicological manifestations. The toxicological hazard assessment of potential human exposures to airborne CNTs and occupational exposure limits for these novel compounds are discussed Address correspondence to Chiu-wing Lam, JSC Toxicology Group, Space Life Sciences, NASA Johnson Space Center, SF23/Wyle, Houston, TX 77058, USA. E-mail: Chiu-wing. 189This document is a U.S. government work and is not subject to copyright in the United States. 190C.-W. LAM ET AL. in detail. Environmental fine PM is known to form mainly from combustion of fuels, and has been reported to be a major contributor to the induction of cardiopulmonary diseases by pollutants. Given that manufactured SWCNTs and MWCNTs were found to elicit pathological changes in the lungs, and SWCNTs...

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Section: Synthesis Of Carbon Nanotubes and Impurities In Syntheticmentioning

confidence: 99%

A Review of Carbon Nanotube Toxicity and Assessment of Potential Occupational and Environmental Health Risks

Lam

James

McCluskey

et al. 2006

Critical Reviews in Toxicology

1,085

672

View full text Add to dashboard Cite

show abstract

“…These nanotubes subsequently coalesce into bundles. Based on spectral emission and laser-induced fluorescence measurements, it was suggested by Scott et al 17 that the carbon for nanotube formation comes from direct ablation as well as from carbon particles suspended in the reaction zone. It was also proposed by them that the confinement of the nanotubes in the reaction zone within the laser beam allows the nanotubes to be purified and annealed during the formation process by laser heating.…”

Section: Laser-ablation Techniquementioning

confidence: 99%

Carbon Nanotube-Based Sensors

Sinha¹,

Ma²,

Yeow³

2006

j nanosci nanotechnol

459

230

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Sensors continue to make significant impact in everyday life. There has been a strong demand for producing highly selective, sensitive, responsive, and cost effective sensors. As a result, research emphasis is on developing new sensing materials and technologies. Carbon nanotubes (CNTs) have many distinct properties that may be exploited to develop next generation of sensors. This manuscript reviews the distinct physical, electronic, and mechanical properties of CNTs. The main thrust of this review is to highlight the present and future research and development work in the area of carbon nanotube sensors for real-world applications. The technical challenges associated with CNT-based sensors, which remain to be fully addressed, have also been outlined at the end of the manuscript. This review aims to act as a reference source for researchers to help them in developing new applications of CNT-based sensors.

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“…In addition to CNTs, spherical carbon onions are interesting because they are expected to have superior lubrication properties [3]. Carbon plasma, generated by laser ablation [4] or arc discharge has been used routinely in the production of fullerenes and CNTs [5].…”

Section: Introductionmentioning

confidence: 99%

Voltage effects on the production of nanocarbons by a unique arc-discharge set-up in solution

Jahanshahi

Raoof

Seresht

2009

Journal of Experimental Nanoscience

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Well graphitised nanocarbons including onion-like fullerenes and single-and multi-walled carbon nanotubes (CNTs) were synthesised in high yield by automatic arc-discharge method in solution. This technique is considered a low-cost method since it does not require any expensive equipment. Herein, an arc discharge full automatic set-up was used for fabrication of CNTs which enables controlling of the gap between the two electrodes and the voltage as well. Carbon nanostructures under a controlled amount of voltage (from 10 to 30 V) were synthesised where Ni : Mo as a catalyst and LiCl 0.25 M as a solution were used. Subsequently, a modified acid treatment method was applied as purification stage of the products. The production rate of CNTs was as high as 7.7 mg min À1 while the voltage was set at 30 V. Scanning electron microscopy and transmission electron microscopy as well as Raman spectroscopy were employed to study the morphology of these carbon nanostructures. The results indicated that CNTs synthesised at a voltage of 30 V had the best quality and elongated straight structures. The mechanism of the voltage conditions for preparing nanocarbons as well as their characterisation are discussed.

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Growth mechanisms for single-wall carbon nanotubes in a laser-ablation process

Cited by 330 publications

References 0 publications

A Review of Carbon Nanotube Toxicity and Assessment of Potential Occupational and Environmental Health Risks

A Review of Carbon Nanotube Toxicity and Assessment of Potential Occupational and Environmental Health Risks

Carbon Nanotube-Based Sensors

Voltage effects on the production of nanocarbons by a unique arc-discharge set-up in solution

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