Carbon Nanotubes--the Route Toward Applications
02 Aug 2002-Science (American Association for the Advancement of Science)-Vol. 297, Iss: 5582, pp 787-792
TL;DR: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects.
Abstract: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.
Citations
More filters
TL;DR: The results highlight the significance of MWCNT SA for HA sorption and the associated influence on sorption of aromatic compounds and suggest that micropore-filling could not be a predominant mechanism.
Abstract: Sorption of humic acid (HA) and aromatic compounds by multiwalled carbon nanotubes (MWCNTs), and their competition on MWCNTs were examined. HA sorption by MWCNTs was regulated by their surface area (SA). Hydrophobic and pi-pi attractions of HA with MWCNTs were main driving forces for their interactions. K(d)/K(ow) values of phenanthrene (Phen), naphthalene (Naph), and 1-naphthol(1-Naph) by individual MWCNTs were positively correlated with their molecular size, suggesting that micropore-filling could not be a predominant mechanism. HA had the lowest competition with Phen and 1-Naph on MWCNT20, due to its greatest abundance of sorption sites. Competition between HA and 1-Naph followed an order MWCNT40 < MWCNT60 < MWCNT100, due to their reduction in SA and porosity. Micropore blockage and direct competition by HA increased with deceasing SA and porosity of MWCNTs. MWCNT20 had much more sorption sites than other MWCNTs, leading to insignificant difference in competition between 1-Naph and Phen with HA. Also, HA had higher competition with Phen on MWCNT40, MWCNT60, and MWCNT100 than 1-Naph. Our results highlight the significance of MWCNT SA for HA sorption and the associated influence on sorption of aromatic compounds. Further, molecular size and hydrophobicity of aromatic compounds strongly affected their competition with HA on MWCNTs.
194 citations
TL;DR: In this paper, the potential positive and negative effects of nanotechnology on the environment are discussed and a strategy for recycling and recovery of nanomaterials and methods are needed to assess whether the potential benefits of nanophotonics outweigh the risks.
194 citations
TL;DR: In this paper, the authors demonstrate the possibility to jam unpurified and unfunctionalized multiwall carbon nanotubes (MWNTs) at the interface of an immiscible blend of polyamide (PA) and ethylene-acrylate (EA) copolymer.
194 citations
TL;DR: In this article, a mechanism by which catalyst deactivation occurs during vertically aligned single-walled carbon nanotube (SWNT) growth is demonstrated, and it is shown that a combination of both Ostwald ripening and subsequent subsurface diffusion leads to loss of the Fe catalyst.
Abstract: A mechanism by which catalyst deactivation occurs during vertically aligned single-walled carbon nanotube (SWNT) growth is demonstrated. We have used both quantitative measurements of nanotube growth rates and ex situ and in situ transmission electron microscopy observations to show that termination of carbon nanotube (CNT) array growth can be intrinsically linked to evolution of the catalyst morphology. Specifically, we find that a combination of both Ostwald ripening and subsequent subsurface diffusion leads to loss of the Fe catalyst, and through direct observations, we correlate this with nanotube growth termination. These observations indicate that careful design of the catalyst and its support − as well as the interaction between the two − is required to maximize nanotube yields.
193 citations
TL;DR: A wearable textile-based humidity sensor for the first time using high strength (∼750 MPa) and ultratough (energy-to-break, 4300 J g-1) SWCNT/PVA filaments via a wet-spinning process is reported.
Abstract: Textile-based humidity sensors can be an important component of smart wearable electronic-textiles and have potential applications in the management of wounds, bed-wetting, and skin pathologies or for microclimate control in clothing. Here, we report a wearable textile-based humidity sensor for the first time using high strength (∼750 MPa) and ultratough (energy-to-break, 4300 J g–1) SWCNT/PVA filaments via a wet-spinning process. The conductive SWCNT networks in the filaments can be modulated by adjusting the intertube distance by swelling the PVA molecular chains via the absorption of water molecules. The diameter of a SWCNT/PVA filament under wet conditions can be as much as 2 times that under dry conditions. The electrical resistance of a fiber sensor stitched onto a hydrophobic textile increases significantly (by more than 220 times) after water sprayed. Textile-based humidity sensors using a 1:5 weight ratio of SWCNT/PVA filaments showed high sensitivity in high relative humidity. The electrical res...
193 citations
References
More filters
TL;DR: The nanotubes sensors exhibit a fast response and a substantially higher sensitivity than that of existing solid-state sensors at room temperature and the mechanisms of molecular sensing with nanotube molecular wires are investigated.
Abstract: Chemical sensors based on individual single-walled carbon nanotubes (SWNTs) are demonstrated. Upon exposure to gaseous molecules such as NO 2 or NH 3 , the electrical resistance of a semiconducting SWNT is found to dramatically increase or decrease. This serves as the basis for nanotube molecular sensors. The nanotube sensors exhibit a fast response and a substantially higher sensitivity than that of existing solid-state sensors at room temperature. Sensor reversibility is achieved by slow recovery under ambient conditions or by heating to high temperatures. The interactions between molecular species and SWNTs and the mechanisms of molecular sensing with nanotube molecular wires are investigated.
5,908 citations
TL;DR: In this paper, the fabrication of a three-terminal switching device at the level of a single molecule represents an important step towards molecular electronics and has attracted much interest, particularly because it could lead to new miniaturization strategies in the electronics and computer industry.
Abstract: The use of individual molecules as functional electronic devices was first proposed in the 1970s (ref 1) Since then, molecular electronics2,3 has attracted much interest, particularly because it could lead to conceptually new miniaturization strategies in the electronics and computer industry The realization of single-molecule devices has remained challenging, largely owing to difficulties in achieving electrical contact to individual molecules Recent advances in nanotechnology, however, have resulted in electrical measurements on single molecules4,5,6,7 Here we report the fabrication of a field-effect transistor—a three-terminal switching device—that consists of one semiconducting8,9,10 single-wall carbon nanotube11,12 connected to two metal electrodes By applying a voltage to a gate electrode, the nanotube can be switched from a conducting to an insulating state We have previously reported5 similar behaviour for a metallic single-wall carbon nanotube operated at extremely low temperatures The present device, in contrast, operates at room temperature, thereby meeting an important requirement for potential practical applications Electrical measurements on the nanotube transistor indicate that its operation characteristics can be qualitatively described by the semiclassical band-bending models currently used for traditional semiconductor devices The fabrication of the three-terminal switching device at the level of a single molecule represents an important step towards molecular electronics
5,258 citations
TL;DR: X-ray diffraction and electron microscopy showed that fullerene single-wall nanotubes (SWNTs) are nearly uniform in diameter and that they self-organize into “ropes,” which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms.
Abstract: The major part of this chapter has already appeared in [1], but because of the length restrictions (in Science), the discussion on why we think this form is given in only brief detail. This chapter goes into more depth to try to answer the questions of why the fullerenes form themselves. This is another example of the very special behavior of carbon. From a chemist’s standpoint, it is carbon’s ability to form multiple bonds that allows it to make these low dimensional forms rather than to produce tetrahedral forms. Carbon can readily accomplish this and it is in the mathematics and physics of the way this universe was put together, that carbon is given this property. One of the consequences of this property is that, if left to its own devices as carbon condenses from the vapor and if the temperature range is just right, above 1000°C, but lower than 1400°C, there is an efficient self-assembly process whose endpoint is C60.
5,215 citations
TL;DR: In this paper, the Young's modulus, strength, and toughness of nanostructures are evaluated using an atomic force microscopy (AFM) approach. And the results showed that the strength of the SiC NRs were substantially greater than those found previously for larger SiC structures, and they approach theoretical values.
Abstract: The Young's modulus, strength, and toughness of nanostructures are important to proposed applications ranging from nanocomposites to probe microscopy, yet there is little direct knowledge of these key mechanical properties. Atomic force microscopy was used to determine the mechanical properties of individual, structurally isolated silicon carbide (SiC) nanorods (NRs) and multiwall carbon nanotubes (MWNTs) that were pinned at one end to molybdenum disulfide surfaces. The bending force was measured versus displacement along the unpinned lengths. The MWNTs were about two times as stiff as the SiC NRs. Continued bending of the SiC NRs ultimately led to fracture, whereas the MWNTs exhibited an interesting elastic buckling process. The strengths of the SiC NRs were substantially greater than those found previously for larger SiC structures, and they approach theoretical values. Because of buckling, the ultimate strengths of the stiffer MWNTs were less than those of the SiC NRs, although the MWNTs represent a uniquely tough, energy-absorbing material.
4,627 citations
TL;DR: The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device and shows linear temperature dependence with a value of 80 microV/K at room temperature.
Abstract: The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is 2 orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a peak at 320 K due to the onset of umklapp phonon scattering. The measured thermoelectric power shows linear temperature dependence with a value of 80 microV/K at room temperature.
3,166 citations