No abstract

A flexible and elastic carbon coil (see figure) has been fabricated using a continuous yarn of carbon nanotube arrays. The processed yarn is both elastic and pliable and can be freely manipulated and molded to any desired shape that is retained after heat treatment. Owing to their highly ordered macroscopic structures, the good electrical and thermal conductivity of the nanotube components, and their good mechanical properties, these carbon nanostructures may find extensive use in a wide range of applications.

We found that very thin carbon nanotube films, once fed by sound frequency electric currents, could emit loud sounds. This phenomenon could be attributed to a thermoacoustic effect. The ultra small heat capacity per unit area of carbon nanotube thin films leads to a wide frequency response range and a high sound pressure level. On the basis of this finding, we made practical carbon nanotube thin film loudspeakers, which possess the merits of nanometer thickness and are transparent, flexible, stretchable, and magnet-free. Such a single-element thin film loudspeaker can be tailored into any shape and size, freestanding or on any insulating surfaces, which could open up new applications of and approaches to manufacturing loudspeakers and other acoustic devices.

We report a simple and effective way of fabricating high-quality carbon nanoscrolls (CNSs), using isopropyl alcohol solution to roll up monolayer graphene predefined on SiO(2)/Si substrates. Transmission electron microscopy studies reveal that the CNS has a tube-like structure with a hollow core surrounded by graphene walls 0.35 nm apart. Raman spectroscopy studies show that the CNS is free of significant defects, and the electronic structure and phonon dispersion are slightly different from those of two-dimensional graphene. Finally, the CNS-based device is fabricated, directly on the SiO(2)/Si substrate. Electrical-transport measurements show that its resistance is weakly gate-dependent but strongly temperature-dependent. In addition, the CNS can sustain a high current density up to 5 x 10(7) A/cm(2), indicating that it is a good candidate for microcircuit interconnects. The controlled fabrication of high-quality CNSs may open up new opportunities for both fundamental and applied research of CNSs.

A superaligned carbon nanotube (CNT) array is a special kind of vertically aligned CNT array with the capability of being converted into continuous fi lms and yarns. The as-produced CNT fi lms are transparent and highly conductive, with aligned CNTs parallel to the direction of drawing. After passing through volatile solutions or being twisted, CNT fi lms can be further condensed into shrunk yarns. These shrunk yarns possess high tensile strengths and Young’s moduli, and are good conductors. Many applications of CNT fi lms and shrunk yarns have been demonstrated, such as TEM grids, loudspeakers, touch screens, etc.

We report the controlled growth of ultralong single-wall carbon nanotube (SWNT) arrays using an improved chemical vapor deposition strategy. Using ethanol or methane as the feed gas, monodispersed Fe-Mo as the catalyst, and a superaligned carbon nanotube (CNT) film as the catalyst supporting frame, ultralong CNTs over 18.5 cm long were grown on Si substrates. The growth rate of the CNTs was more than 40 mum/s. No catalyst-related residual material was found on the substrates due to the use of a CNT film as the catalyst supporting frame, facilitating any subsequent fabrication of SWNT-based devices. Electrical transport measurements indicated that the electrical characteristics along a single ultralong SWNT were uniform. We also found that maintaining a spatially homogeneous temperature during the growth process was a critical factor for obtaining constant electrical characteristics along the length of the ultralong SWNTs.

A straightforward roll‐to‐roll process for fabricating flexible and stretchable superaligned carbon nanotube films as transparent conducting films is demonstrated. Practical touch panels assembled by using these carbon nanotube conducting films are superior in flexibility and wearability—and comparable in linearity—to touch panels based on indium tin oxide (ITO) films. After suitable laser trimming and deposition of Ni and Au metal, the carbon nanotube film possesses excellent performance with two typical values of sheet resistances and transmittances (208 Ω □−1, 90% and 24 Ω □−1, 83.4%), which are comparable to ITO films and better than the present carbon nanotube conducting films in literature. The results provide a route to produce transparent conducting films more easily, effectively, and cheaply, an important step for realizing industrial‐scale applications of carbon nanotubes for transparent conducting films.

Great efforts have been made toward the syntheses of nanocomposites of inorganic materials and carbon nanotubes (CNTs), [1][2][3][4][5] with the aim of exploiting the unique properties of CNTs (such as a high aspect ratio, low mass, flexibility, a high mechanical strength, and high electrical and thermal conductivities) for applications in heterogeneous catalysis, [2] fuel cells, [3] supercapacitors, [4] lithium-ion batteries (LIBs), [5] and optoelectronic devices.[6] The performances of these nanocomposites should be significantly affected by at least one of three key structural factors: uniformity, maintenance of the electrical contacts between CNTs, and porosity. Therefore, it is of fundamental interest to develop synthetic strategies for uniformly loading inorganic materials onto the surfaces of CNTs and CNT bundles within mesoporous sheets without disturbing the electrical contacts between the CNTs, so that such materials can be used in fuel cells, supercapacitors, and LIBs. To the best of our knowledge, the only previous attempt (in which layers of V 2 O 5 ÁxH 2 O with a 6 nm thickness were electrochemically loaded onto CNT films) had not been fully successful; aggregates were clearly observed on the surface of the films.[4b]Here, we report the uniform loading of SnO 2 nanoparticles (NPs) onto a CNT network composed of 1 Â 1 cross-stacked sheets (see Scheme S1, Supporting Information); the NPs are observed on the surface of each multiwalled CNT and of each CNT bundle within the network. This technique may be useful in the fabrication of high-capacity anodes for rechargeable LIBs. Additional considerations for the design of the novel composite arise because all three key factors are very important to this application.Tin-based materials have also attracted great attention as potential substitutes for current carbonaceous materials because of their higher specific capacities (981 mA h g À1 for Sn, 1491 mA h g À1 for SnO 2 , assuming that all Sn was oxidized to Sn 4þ , approximately 360 mA h g À1 for C-based materials). [7][8][9] However, anodes of such high capacity usually suffer severe capacity fading stemming from both the quick aggregation of tin particles and the huge volume change (over 300%) during Li þ insertion/extraction cycles, which causes pulverization of the anodes and electrical detachment of active materials. [9] Reducing the materials' size down to the nanoscale and dispersing the materials into mesoporous structures have proved very effective in solving the problems of similar systems.[5b,10] There have already been some reports of applying inorganic-CNT composites to high-capacity anodes for LIBs, [5b-d] but all of these composites were prepared using CNTs as collectors for sediments, so carbon black and polymer binders had to be used to lower the resistance and hold the electrodes together. In contrast, CNT sheets have been demonstrated to be very attractive candidates for freestanding (no need for copper foil substrates as current collectors) and binder-free anodes (no need for po...