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: An organic thiolate/disulfide redox couple with low absorption in the visible region was developed for use in fabricating novel dye-sensitized photovoltaic wires with an aligned carbon nanotube (CNT) fiber as the counter electrode, and greatly outperforms the conventional Pt counter electrode.
Abstract: An organic thiolate/disulfide redox couple with low absorption in the visible region was developed for use in fabricating novel dye-sensitized photovoltaic wires with an aligned carbon nanotube (CNT) fiber as the counter electrode. These flexible wire devices achieved a maximal energy conversion efficiency of 7.33%, much higher than the value of 5.97% for the conventional I–/I3– redox couple. In addition, the aligned CNT fiber also greatly outperforms the conventional Pt counter electrode with a maximal efficiency of 2.06% based on the thiolate/disulfide redox couple.
126 citations
TL;DR: In this article, the authors demonstrate that growth of millimeter-high carbon nanotube (CNT) forests terminates abruptly after first exhibiting a steady decay in growth rate, accompanied by a distinct loss of alignment among the CNTs, quantified by small-angle x-ray scattering.
Abstract: Real-time height measurements demonstrate that growth of millimeter-high carbon nanotube (CNT) forests terminates abruptly after first exhibiting a steady decay in growth rate. Termination is accompanied by a distinct loss of alignment among the CNTs, which is quantified by small-angle x-ray scattering. Previously suggested diffusion-limited and decay-limited models of kinetics accurately fit the growth period, yet fail to capture the termination behavior and incorrectly predict that growth will continue for much longer durations than observed. It appears that structural disorder is a distinct chemical and/or mechanical signature of self-terminated CNT forest growth.
126 citations
TL;DR: It was found that the resistance stability of the network was effectively improved through thermal annealing and the humidity sensitivity was obtained by measuring the resistance of the MWCNT network with different relative humidity at room temperature.
Abstract: This paper presents an investigation on the humidity sensitivity of deposited multi-walled carbon nanotube (MWCNT) networks using ac dielectrophoresis (DEP) between interdigitated electrodes (IDEs). MWCNTs dispersed in ethanol were trapped and enriched between IDEs on a Si/SiO2 substrate under a positive DEP force. After the DEP process, the ethanol was evaporated and the MWCNT network on a substrate with IDEs was put into a furnace for repeated thermal annealing. It was found that the resistance stability of the network was effectively improved through thermal annealing. The humidity sensitivity was obtained by measuring the resistance of the MWCNT network with different relative humidity at room temperature. The experimental results show the resistance increases linearly with increasing the relative humidity from 25% to 95% RH with a sensitivity of 0.5%/%RH. The MWCNT networks have a reversible humidity sensing capacity with response time and recovery time of about 3 s and 25 s, respectively. The resistance is dependent on temperature with a negative coefficient of about −0.33%/K in a temperature range from 293 K to 393 K.
126 citations
Cites background from "Carbon Nanotubes--the Route Toward ..."
...A variety of promising applications have been considered, including sensors, field emission displays, nanoelectronic devices, conductive composites, etc [1]....
[...]
01 Jun 2005
TL;DR: The results imply that the Pd-SWNT composite has good potential applications in fuel cells and may be attributed to the high dispersion of palladium catalysts and the particular properties of SWNT supports.
Abstract: Palladium (Pd) nanoparticles were electrochemically dispersed on single-walled carbon nanotubes (SWNTs) by electroreduction of octahedral Pd(IV) complex formed on the SWNT surface. The structure and nature of the resulting Pd-SWNT composites were characterized by transmission electron microscopy and X-ray diffraction. The electrocatalytic properties of the Pd/SWNT electrode for hydrazine oxidation have been investigated by cyclic voltammetry; high electrocatalytic activity of the Pd/SWNT electrode can be observed. This may be attributed to the high dispersion of palladium catalysts and the particular properties of SWNT supports. The results imply that the Pd-SWNT composite has good potential applications in fuel cells.
126 citations
TL;DR: In this paper, electrical conductivity measurements and modeling aspects of carbon nanotube (CNT)/polymer composites enabled via fused filament fabrication (FFF) additive manufacturing are presented.
Abstract: We present electrical conductivity measurements and modeling aspects of carbon nanotube (CNT)/polymer composites enabled via fused filament fabrication (FFF) additive manufacturing (AM). CNT/polylactic acid (PLA) and CNT/high density polyethylene (HDPE) filament feedstocks were synthesized through melt blending with controlled CNT loading to realize 3D printed polymer nanocomposites. Electrical conductivity of 3D printed CNT/PLA and CNT/HDPE composites was measured for various CNT loadings. Low percolation thresholds were obtained from measured data as 0.23 vol. % and 0.18 vol. % of CNTs for CNT/PLA and CNT/HDPE nanocomposites, respectively. Moreover, a micromechanics-based two-parameter agglomeration model was developed to predict the electrical conductivity of CNT/polymer composites. We further show that the two agglomeration parameters can also be used to describe segregated structures, wherein nanofillers are constrained to certain locations within the matrix. To the best of our knowledge, this is the first ever electrical conductivity model to account for segregation of CNTs in the matrix. A good agreement between measured conductivity and predictions demonstrates the adequacy of the proposed model. We further evince the robustness of the model by accurately capturing the conductivity measurements reported in the literature for both elastomeric and thermoplastic nanocomposites. The findings of the study would provide guidelines for the design of electro-conductive polymer nanocomposites.
126 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