Search

In this perspective, we outline that a space borne gravitational wave detector network combining LISA and Taiji can be used to measure the Hubble constant with an uncertainty less than 0.5% in ten years, compared with the network of the ground based gravitational wave detectors which can measure the Hubble constant within a 2% uncertainty in the next five years by the standard siren method. Taiji is a Chinese space borne gravitational wave detection mission planned for launch in the early 2030 s. The pilot satellite mission Taiji-1 has been launched in August 2019 to verify the feasibility of Taiji. The results of a few technologies tested on Taiji-1 are presented in this paper. Gravitational wave astronomy has opened the door to test general relativity and the effect of gravity in the Universe. The authors present the capabilities of an overlap between space gravitational wave detectors LISA and Taiji to constrain the Hubble constant to 0.5%, in 10 years, and what can be learned from the satellite pilot Taiji-1 launched in 2019.

Harvesting energy from water movement has aroused extensive and intensive interest because of its great potential in both energy-related field and wearable electronics. In this work, simply bridging two carbon nanotube (CNT) electrodes by HCl/polyvinyl alcohol (PVA) electrolyte gel with CaCl2 in one side, a novel moisture induced self-charging device (MISD) was successfully fabricated. The MISD can be directly charged to 0.348 V in a humid environment without any complex experimental configuration and the harvesting energy can be effectively stored. The self-charging behaviors under various humid conditions have been explored. The self-charging property is based on the automatic electrolyte diffusion, which is driven by water absorption from moisture by CaCl2. The diffusion can reorient and dislocate conductive ions and induce a potential across the bridge. The application possibility was demonstrated by scaling up MISDs in series to power a timer. Output improvement of a single MISD is also available based on a sandwich like structure, which can reach 0.243 mW cm−2. Besides its application potential in wearable and smart electronics, the MISD also provides a reference for the novel utilization of moisture in energy harvesting and storage.

Transition metal dichalcogenides (TMDs) are van der Waals layered materials with sizable and tunable bandgaps, offering promising platforms for two-dimensional electronics and optoelectronics. To this end, the bottleneck is how to acquire high-quality single crystals in a facile and efficient manner. As one of the most widely employed method of single-crystal growth, conventional chemical vapor transport (CVT) generally encountered problems including the excess nucleation that leads to small crystal clusters and slow growth rate. To address these issues, a seed crystal is introduced to suppress the nucleation and an inner tube is adopted as both a separator and a flow restrictor, favoring the growth of large-size and high-quality TMD single crystals successfully. Three examples are presented, the effective growth of millimeter-sized MoSe2 and MoTe2 single crystals, and the greatly shortened growth period for PtSe2 single crystal, all of which are synthesized in high quality according to detailed characterizations. The mechanism of seeded CVT is discussed. Furthermore, a phototransistor based on exfoliated multi-layered MoSe2 displays excellent photoresponse in ambient conditions, and considerably rapid rise and fall time of 110 and 125 us are obtained. This work paves the way for developing a facile and versatile method to synthesize high-quality TMD single crystals in laboratory, which could serve as favorable functional materials for potential low-dimensional optoelectronics.

Based on porous carbon nanotube/polyaniline composite (CNT/PANI) and poly(vinyl alcohol) gel, we fabricated centimeter-sized hydrocapacitors with dual functions of energy conversion and storage with an efficient low-cost method. Owning to excellent hydrophily and large specific capacitance of CNT/PANI, the hydrocapacitors can easily convert energy from water movement induced by capillarity, gravity, or air pressure difference into electricity and store the generated electricity. Especially, sandwich-like hydrocapacitors outputted large current of 1.65 mA through an external load of 100 Ω, and hydrocapacitors showed good extendibility by connecting in series. To explain the mechanism of hydrocapacitors in this work, a possible model based on capillarity and traditional streaming potential was proposed and discussed. Hydrocapacitors here also provide a reference for future integration of nanogenerators and energy storage parts.

Carbon nanotubes (CNTs) and other related CNT-based materials with a high thermal conductivity can be used as promising heat dissipation materials. Meanwhile, the miniaturization and high functionality of portable electronics, such as laptops and mobile phones, are achieved at the cost of overheating the high power-density components. The heat removal for hot spots occurring in a relatively narrow space requires simple and effective cooling methods. Here, an auxiliary passive cooling approach by the aid of a flat plate (aluminum-magnesium alloy) is investigated to accommodate heat dissipation in a narrow space. The cooling efficiency can be raised to 43.5%. The cooling performance of several CNT-based samples is compared under such circumstances. Heat dissipation analyses show that, when there is a nearby plate for cooling assistance, the heat radiation is weakened and natural convection is largely improved. Thus, improving heat radiation by increasing emissivity without reducing natural convection can effectively enhance the cooling performance. Moreover, the decoration of an auxiliary cooling plate with sprayed CNTs can further improve the cooling performance of the entire setup.

It is known that carbon nanotubes (CNTs) possess a high light absorption coefficient with a very broad spectrum, showing good potential for solar-thermal conversion. Bi2Te3 is a typical thermoelectric material with high thermoelectric conversion efficiency. In this study, we first fabricated several simple elements based on p- and n-type Bi2Te3 respectively. By integrating p- and n-type elements in series, we constructed a novel solar thermoelectric conversion device covered with 0.32 g/m2 CNT sheets, which showed a high light absorption coefficient and generated a large short-circuit current (Isc) of 200 mA. The size of the cross section of each series element was 0.19×0.19 cm2. Thus, the short-circuit current density (Jsc) was as high as 5520 mA/cm2. The open-circuit voltage (Voc) of the device reached 400 mV. Each element of the device displayed a power conversion efficiency (PCE) of 2.1% in the near-infrared (NIR) region by a narrow band diode laser source with light flux of 100 mW/cm2 without using any optical or thermal concentrator. Furthermore, the device is stable, durable and capable of operating at high temperatures and thus is promising for converting sunlight into electricity. This work provides a simple and convenient approach to prepare solar-energy conversion devices for large-scale applications in the future.

The zinc-based primary batteries have various merits including the low cost, high-security and reasonable energy, but their one-time use and low power performance limit the wider applications. Compared with the primary batteries, the supercapacitor has an extra higher cycling performance and power capability, but its specific energy is lower. Here we originally achieve a novel hybrid battery combined of a zinc-based primary battery and a supercapacitor through a unique assembly method. In this new structure, two symmetrical carbon nanotube/polyaniline nanoporous composites as supercapacitor electrodes are inserted in a zinc–manganese dioxide primary battery system with a way in series. Meanwhile, a special technique is used to form excellent conductive connections between the supercapacitor electrodes and the primary battery cathode and anode, respectively. This hybrid battery shows both a high specific power similar to that of the supercapacitor and a high specific energy comparable to that of the primary battery. It is more striking that the rechargeable character of this hybrid battery is much more excellent. Its specific capacity retained 75% after 500 cycles of charge–discharge at the high current density of 2 A g−1 while the coulombic efficiency kept at 100%. These notable improvements are attributed to the special design on the structure and chemistry system of the hybrid battery combining the merits of both the primary battery and the supercapacitor.

In this work, we report our studies related to the natural-convective heat transfer properties of carbon nanotube (CNT) sheets. We theoretically derived the formulas and experimentally measured the natural-convective heat transfer coefficients (H) via electrical heating method. The H values of the CNT sheets containing different layers (1, 2, 3, and 1000) were measured. We found that the single-layer CNT sheet had a unique ability on heat dissipation because of its great H. The H value of the single-layer CNT sheet was 69 W/(m(2) K) which was about twice of aluminum foil in the same environment. As the layers increased, the H values dropped quickly to the same with that of aluminum foil. We also discussed its roles on thermal dissipation, and the results indicated that the convection was a significant way of dissipation when the CNT sheets were applied on macroscales. These results may give us a new guideline to design devices based on the CNT sheets.

Binder-free LiCoO(2) -SACNT cathodes with excellent flexibility and conductivity are obtained by constructing a continuous three-dimensional super-aligned carbon nanotube (SACNT) framework with embedded LiCoO(2) particles. These binder-free cathodes display much better cycling stability, greater rate performance, and higher energy density than classical cathodes with binder. Various functional binder-free SACNT composites can be mass produced by the ultrasonication and co-deposition method described in this paper.

The carbon nanotube/polyaniline (CNT/PANI) composites have important potential applications as the electrodes in energy storage devices for their attractive electrochemical properties. In this work, we report a novel method to prepare the interesting paper-like CNT/PANI composites by using the CNT network as the template. Compared with the conventional brittle CNT/PANI composites, these paper-like composites were much thin and flexible. This work demonstrates a new approach, which may transform a brittle polymer into flexible films. Meanwhile, these film electrodes showed much superior electrochemical performance such as higher specific capacitance, lower internal resistivity, and more stability under different current loads. These paper-like composite electrodes have promising applications in new kinds of energy storage devices. Keywords: Supercapacitor, Buckypaper, Polyaniline, Composite electrode, Specific capacitance

The work function of carbon nanotubes might depend on their diameters and the number of walls, and be different for their tips and sidewalls. Here we report the work function measurement of single-walled, double-walled, and multiwalled carbon nanotubes by investigating the thermionic emission from the middle of their bundles. It is found that the sidewall work functions of the three kinds of carbon nanotubes are all around 4.7-4.9 eV; the diameter and the numbers of walls have no obvious influence on their work functions. For the carbon nanotube bundle with some tips appearing in the middle, the measured work function is smaller than without tips, indicating that the work function of tips is smaller than that of the sidewalls. This tip effect also results in a difference in the thermionic emission characteristic, implying non-uniform work function distribution along the bundle.

Laser irradiated carbon nanotubes in vacuum can emit dazzling yellow light due to the laser heating effect. We investigated the phonon frequency shifts of as irradiated carbon nanotube bundles by Raman spectroscopy under ultraviolet laser illumination (325 nm, 2.4 mW), the G band peak position was found to shift 50 cm-1 to lower wave number. By considering the temperature coefficient of the G band shift, the local temperature of the illuminated spot was predicted to be nearly 2000K. This temperature had a linear relationship with the incident laser power, and also was greatly influenced by the pressure of the vacuum chamber. The photoluminescence of the CNT bundle was also studied, which exhibits an oscillation of 0.1 eV, a possible origin of the oscillation was discussed.

Raman spectroscopy has been used in the identification of crystallography property of nanosemiconductors. The identified result by Raman spectroscopy is consistent with that by the X-ray refraction (XRD) in bulk materials and in non-polar semiconductors, e.g., porous silicon and Si nanowires. But for nano-polar semiconductor SiC, GaN and ZnO, their Raman spectra can not described by the crystalline model but the amorphous model related to the phonon density of states (PDOS). Moreover, it is found for these samples that Raman frequencies excided by different incident wavelengths were not changed, matching the no change characteristic of PODS with sample sizes. Therefore above results may indicate that these nano-polar semiconductors possess of amorphousness-like nature although they are crystalline by XRD measurements. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Cyanoacrylate–carbon nanotube arrays are prepared by embedding carbon nanotube (CNT) arrays grown on silicon substrate in cyanoacrylate adhesive. Upon laser treatment, enhanced field emission properties are obtained. Moreover, the binding force between the carbon nanotubes and the substrate is strengthened by the cyanoacrylate adhesive. When the field emission current is large enough at high electric field, the carbon nanotubes cannot be pulled out of the substrate by electric field force. A large field emission current can be obtained from cyanoacrylate–carbon nanotube arrays at relatively low voltage just by decreasing the distance between the anode and the cathode.

This article presents our recent work in the controlled synthesis of multiwalled (MWNT) and single-walled nanotubes (SWNT) with ordered architectures. The general synthesis approach involves chemical vapor deposition using rationally designed catalyst and substrates. The results include self-oriented MWNTs, individual SWNTs grown from controlled surface sites, and structures of suspended SWNTs along well-defined directions. The chemically derived nanotube architectures have opened up new possibilities in fundamental characterization and potential applications of nanotube materials. Systematic electron transport measurements are carried out to elucidate the electrical properties of various classes of SWNTs and to explore the physics in one-dimensional systems. High-performance electrical devices based on individual SWNTs are enabled by combining synthesis and microfabrication approaches.

Unpurified carbon nanotubes were introduced to silicone elastomer to investigate their effect on the thermal conductivity. Microstructure studies by a scanning electron microscope showed that the carbon nanotubes (CNTs) can be well dispersed in the matrix by the grinding method. No notable agglomerates or phase separation between the carbon and silicone matrix were observed, and the CNTs were individually in random orientation. The thermal conductivities of the composites were measured with the ASTM (American Society of Testing Materials) D5470 method. The thermal conductivities κ were found to increase with the carbon amount. There was a 65% enhancement in κ with 3.8 wt % CNT loading. The enhancement by equal loading of carbon black was found to be a little lower than that by the CNT loading. The composites loaded with CNTs displayed an abrupt increase in the electrical conductivity.

Polarized light emission from multiwalled carbon nanotube (MWNT) bundles due to current heating is observed. The spectra of the emitted light fit well with the blackbody radiation distribution. And the emitted light is partially polarized with a degree of 0.33 along the axis of MWNT bundle, which is qualitatively explained in terms of one-dimensional structure of carbon nanotubes (CNTs). Negative temperature-dependent resistance is also observed, which is different from normal metal filaments. The MWNT bundles are very stable at high temperature in vacuum during light emitting, indicating that CNTs can be a good candidate as polarized incandescent light sources.

High-density buckypapers were obtained by using well-aligned carbon nanotube arrays. The density of the buckypapers was as high as 1.39 g cm(-3), which is close to the ultimate density of ideal buckypapers. Then we measured the transport and mechanical properties of the buckypapers. Our results demonstrated that its electrical and thermal conductivities could be almost linearly improved by increasing its density. In particular, its superior thermal conductivity is nearly twice that of common metals, which enables it a lightweight and more efficient heat-transfer materials. The Young's modulus of the buckypapers could reach a magnitude over 2 GPa, which is greatly improved compared with previous reported results. In view of this, our work provided a simple and convenient method to prepare high-density buckypapers with excellent transport and mechanical properties.

The binder-free title cathodes are prepared by an ultrasonication and codeposition technique from dispersions of super-aligned carbon nanotubes and LiCoO2 in an organic solvent such as EtOH, iPrOH, or acetone (intensive ultrasonication, 300—600 W, 10 min).

In this work, we show that embedding super-aligned carbon nanotube sheets into a polymer matrix (polydimethylsiloxane) can remarkably reduce the coefficient of thermal expansion of the polymer matrix by two orders of magnitude. Based on this unique phenomenon, we fabricated a new kind of bending actuator through a two-step method. The actuator is easily operable and can generate an exceptionally large bending actuation with controllable motion at very low driving DC voltages (700 V/m). Furthermore, the actuator can be operated without electrolytes in the air, which is superior to conventional carbon nanotube actuators. Proposed electrothermal mechanism was discussed and confirmed by our experimental results. The exceptional bending actuation performance together with easy fabrication, low-voltage, and controllable motion demonstrates the potential ability of using this kind of actuator in various applicable areas, such as artificial muscles, microrobotics, microsensors, microtransducers, micromanipulation, microcantilever for medical applications, and so on.

In recent years, much effort have been dedicated to achieve thin, lightweight and even flexible energy-storage devices for wearable electronics. Here we demonstrate a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H(2)SO(4)-polyvinyl alcohol gel electrolyte. The thickness of the entire device is much comparable to that of a piece of commercial standard A4 print paper. Under its highly flexible (twisting) state, the integrate device shows a high specific capacitance of 350 F/g for the electrode materials, well cycle stability after 1000 cycles and a leakage current of as small as 17.2 μA. Furthermore, due to its polymer-based component structure, it has a specific capacitance of as high as 31.4 F/g for the entire device, which is more than 6 times that of current high-level commercial supercapacitor products. These highly flexible and all-solid-state paperlike polymer supercapacitors may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.

It is known that single-walled carbon nanotubes (SWNTs) strongly absorb light, especially in the near-infrared (NIR) region, and convert it into heat. In fact, SWNTs also have considerable ability to convert heat into electricity. In this work, we show that SWNT sheets made from as-grown SWNT arrays display a large positive thermoelectric coefficient (p-type). We designed a simple SWNT device to convert illuminating NIR light directly into a notable voltage output, which was verified by experimental tests. Furthermore, by a simple functionalization step, the p- to n-type transition was conveniently achieved for the SWNT sheets. By integrating p- and n-type elements in series, we constructed a novel NIR opto-electronic power source, which outputs a large voltage that sums over the output of every single element. Additionally, the output of the demo device has shown a good linear relationship with NIR light power density, favorable for IR sensors.

This article presents our recent work in the controlled synthesis of multiwalled (MWNT) and single-walled nanotubes (SWNT) with ordered architectures. The general synthesis approach involves chemical vapor deposition using rationally designed catalyst and substrates. The results include self-oriented MWNTs, individual SWNTs grown from controlled surface sites, and structures of suspended SWNTs along well-defined directions. The chemically derived nanotube architectures have opened up new possibilities in fundamental characterization and potential applications of nanotube materials. Systematic electron transport measurements are carried out to elucidate the electrical properties of various classes of SWNTs and to explore the physics in one-dimensional systems. High-performance electrical devices based on individual SWNTs are enabled by combining synthesis and microfabrication approaches.

Single-walled carbon nanotubes (SWNTs) with five different C13/C12 isotope compositions and well-separated Raman peaks have been synthesized and conjugated to five targeting ligands in order to impart molecular specificity. Multiplexed Raman imaging of live cells has been carried out by highly specific staining of cells with a five-color mixture of SWNTs. Ex vivo multiplexed Raman imaging of tumor samples uncovers a surprising up-regulation of epidermal growth factor receptor (EGFR) on LS174T colon cancer cells from cell culture to in vivo tumor growth. This is the first time five-color multiplexed molecular imaging has been performed in the near-infrared (NIR) region under a single laser excitation. Near zero interfering background of imaging is achieved due to the sharp Raman peaks unique to nanotubes over the low, smooth autofluorescence background of biological species., Comment: Published in Nano Research

In recent years carbon-nanotube-based thermal interface materials have shown great potential for solving the thermal management problem of integrated circuits and nanodevices. For a long time, the exceptionally high thermal boundary resistances (TBRs) between carbon nanotubes (CNTs) and their surroundings have been suspected as a major factor to restraining their performance. But so far, there are few or no reported work to determine or compare the TBRs between CNTs and various materials. In this paper, we carefully design and carry out the TBR measurements of CNTs in contact with metal and polymer materials, and we present a conclusion that the CNT/polymer generally gives a lower TBR compared to the CNT/metal, which seems a little counterintuitive. We further suggest that the larger CNT-metal TBRs arise from the smaller phonon-mode overlapping between the CNT and the metals at low frequencies, and the low phonon transmission coefficient at the metal-CNT interface in the intermediate and high frequency range. This work may inspire deeper understanding of the TBR and shed light on related theoretical and applied research.

The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development of nanotube devices integrated into silicon technology.

The multiwalled carbon nanotube (MWCNT) yarns converted from superaligned MWCNT arrays are self-assembled sheetlike structure in which MWCNTs are aligned along the stretching direction and will shrink into a tight fiber after passing through volatile solvents. In this paper, we report the comparative studies on the physical properties of the MWCNT sheets and shrunk yarns. The major differences between them lie in the surface area and intertube interactions, which result in different mechanical and electrical properties. Their surface areas were measured according to the energy conservation law and Stefan-Boltzmann law, manifesting that the surface area of the sheet is around 30 times larger than that of the shrunk yarn. With the measured surface area, the thermionic emission from them was further studied. There is no difference in their work function, emission efficiency, as well as Richardson's emission constant which is approximately equal to the theoretical value of $120.4\phantom{\rule{0.3em}{0ex}}\mathrm{A}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}$. The electronic transport properties were studied in low temperature ranging from $3\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}390\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and high temperature around $1100--2300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. In all the temperature range, there exists a resistance reduction from the MWCNT sheet to the shrunk yarn which was attributed to the increase of intertube crosstalk points between neighboring MWCNTs. It is also found that $R$ decreases with increasing temperature until $1800\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ above which $R$ increases due to the electron-phonon scattering at high $T$.

Gallium nitride nanorods were prepared through a carbon nanotube–confined reaction. Ga 2 O vapor was reacted with NH 3 gas in the presence of carbon nanotubes to form wurtzite gallium nitride nanorods. The nanorods have a diameter of 4 to 50 nanometers and a length of up to 25 micrometers. It is proposed that the carbon nanotube acts as a template to confine the reaction, which results in the gallium nitride nanorods having a diameter similar to that of the original nanotubes. The results suggest that it might be possible to synthesize other nitride nanorods through similar carbon nanotube–confined reactions.

Flood disasters caused by extreme hydrologic events have long been a major threat to human well-being. Our struggles against disasters have been documented in historical records since Biblical times. Today, the potential losses due to a major flood disaster are tremendous. As the methods to counter such disasters increase, the public tolerance for such disasters decrease. In spite of great achievements by scientists, flood disaster management is still not an exact science and involves a great deal of uncertainty. There are several types of uncertainty, including socio-economic, health, and technology induced risk. Due to space limitation, this paper is limited to a discussion of the technology-induced-uncertainty of flood disaster management.

We show that single walled carbon nanotubes with different isotope compositions exhibit distinct Raman Gband peaks and can be used for multiplexed multi-color Raman imaging of biological systems. Cancer cells with specific receptors are selectively labeled with 3 differently colored SWNTs conjugated with various targeting ligands including Herceptin, anti-Her2, Erbitux, anti-Her1, and RGD peptide, allowing for multi-color Raman imaging of cells in a multiplexed manner. SWNT Raman signals are highly robust against photo-bleaching, allowing long term imaging and tracking. With narrow peak features, SWNT Raman signals are easily differentiated from the auto-fluorescence background. The SWNT Raman excitation and scattering photons are in the near-infrared region, which is the most transparent optical window for biological systems in vitro and in vivo. Thus, SWNTs are novel Raman tags promising for multiplexed biological detection and imaging., Journal of the American Chemical Society, in press

An acoustic projection screen includes a screen base and a carbon nanotube layer. The carbon nanotube layer is attached to the screen base and connected to electrodes.

With increasing excitation wavelength from 514 to 782 nm, a significant difference in the Raman spectra of SiC nanorods was observed as compared to bulk material. The intensity ratio of the LO mode to that of the IF mode increases with the excitation wavelength increasing. This has been identified as resonant Raman scattering caused by Frohlich interaction.

We present a flexible electronic material fabricated by incorporating multiwall carbon nanotubes (MWNTs) into poly(dimethylsiloxane) rubber (0.35 wt % MWNT loading is most appropriate in our study). Resistance-temperature data for different composites (0.35–5 wt %) are analyzed within Coulomb gap variable range hopping model, which well explains the semiconductor behaviors in low MWNT loading composites. Field effect transistors fabricated using 0.35 wt % composite show a p-type behavior with a high effective mobility of 1.98 cm2 V s and linear transconductance 8.34×10−8 S at 2.5 V drain voltage. These results suggest an optional way of seeking for high-quality flexible electronic materials.

The authors report an electrothermal actuator, which is fabricated by involving carbon nanotube network into the silicone elastomer. The actuators exhibit excellent performances as good as normal dielectric elastomer actuators while working under much lower voltages (e.g., 1.5Vmm−1). They are longitudinal actuators and there is no need for stacking or rolling sheets of materials. In addition, they can satisfy the demand of different voltage applications ranging from dozens of voltages to thousands of voltages by using different carbon nanotube loading composites. Visible maximal strain of 4.4% occurs at an electric power intensity around 0.03Wmm−3.

The authors report the synthesis of multiwalled carbon nanotubes on transparent substrates by utilizing a diode laser to locally heat the catalysts to high temperature. Well-aligned bamboo-shaped multiwalled carbon nanotubes can be synthesized on glass substrate covered with a carbon black layer. If the carbon black was substituted by the commercial graphite inner coating, randomly oriented but high quality multiwalled carbon nanotubes were obtained with excellent field emission performance. This approach facilitates the fabrication of multiwalled carbon nanotube field emitters for field emission flat panel displays without limitations on the geometry size and temperature requirement of the substrate.

In this work the authors investigated the electrical conducting properties of multiwalled carbon nanotube (MWNT) networks in the flexible polydimethylsiloxane rubber as a function of applied voltages. The results indicated that the I-V curves showed nonlinear relationships, which can be fitted to quadratic functions. The electrical resistance of the samples varies with the voltages more sharply in lower range. The nonlinear mechanism was related to the materials system including both the MWNTs and the matrix material. Furthermore, the I-V characteristic of the MWNT network/ZnO nanocomposite layer junction has shown a well rectified behavior at low voltages.

Since long and slender carbon nanotubes (CNTs) are usually self-entangled, we propose a factor, length efficiency, in this study to analyze the thermal conductivity of nanocomposites with CNT loading. Theoretical analysis reveals that an appropriate length distribution of CNTs could improve their length efficiency and more effectively enhance the thermal conductivity of the composites. This theory was supported by the experimental results of glycerin or silicone composites with modified CNT loading. Results also indicated that when length efficiency was taken into account, interfacial resistance effect would be less serious.

Interfaces and close proximity between carbon nanotubes (CNTs) and the matrix are very important for their thermal conductance of CNT composites. Chemical modifications to the CNTs are a possible approach to manage the interfacial interactions. In this study, the nanocomposites of the polydimethylsiloxanerubber with 2wt% chemical-treated CNTs loading were prepared to investigate the influence of chemical modifications and defects on the thermal conductivity of CNT composites. The CNTs treated in concentrated nitric acid showed remarkable changes which could be seen directly by their morphologies. The thermal conductivities κ of the composites were measured carefully in comparison with that by the raw CNT loading. The κ varied somewhat up and down with the treatment level. This study reveals that moderate chemical modifications are beneficial to improve the thermal conductivity of the CNT composites. However, their negative effects to the thermal conductance are more remarkable than the theoretical anticip...