We report the direct synthesis of strong, highly conducting, and transparent single-walled carbon nanotube (SWNT) films. Systematically, tests reveal that the directly synthesized films have superior electrical and mechanical properties compared with the films made from a solution-based filtration process: the electrical conductivity is over 2000 S/cm and the strength can reach 360 MPa. These values are both enhanced by more than 1 order. We attribute these intriguing properties to the good and long interbundle connections. Moreover, by the help of an extrapolated Weibull theory, we verify the feasibility of reducing the interbundle slip by utilizing the long-range intertube friction and estimate the ultimate strength of macroscale SWNTs without binding agent.Because of their optical transparency and unique electric properties together with mechanical flexibility, film-like single-walled carbon nanotubes (SWNTs) are attractive not only for fundamental researches but also potential applications. For example, large optical nonlinearity, 1 subpicosecond optical response 2,3 and bolometric infrared photoresponse 4 have been observed in SWNT films, and the feasibilities of using SWNT films or networks as sensors, 5,6 diodes, 7 and field effect transistors 8 have already been demonstrated. Recently, highly conducting transparent SWNT films (tSWNTs) have also been fabricated by a kind of controlled filtration-deposition process, 9 which could be used as transparent electrodes for GaN/InGaN or flexible organic lightemitting diodes. 10,11 However, almost all of the above reports focused on the post-treated SWNT films, which are obtained through solution-based filtration processes. As known, to obtain high conductivity, SWNTs must be well purified and dispersed from sootlike morphology, which usually costs several days and leaves unrecyclable chemical residues. Besides, the comparative low strength of these films is one of the challenges for their applications, especially in the field of high-strength enforcement sheets.Here we report the direct synthesis of strong, highly conducting, and transparent films through a further developed floating catalyst CVD (FCCVD) technique that is based on the methods of producing large-scale nonwoven SWNTs. 12 As catalyst source, ferrocene/sulfur powder is heated to 65-85°C and flowed into a reaction zone by the mixture of 1000 sccm argon and 1-8 sccm methane. The growth rates of the films are mainly determined by the sublimation rate of the catalysts. Under typical conditions, after 30 min growth, thin films with a thickness of 100 nm will form in the high-temperature zone (over 600°C) of the quartz tube and can be easily peeled off. This type of large-area freestanding film can be easily handled for further researches. Raman scattering and HRTEM images show that most CNTs in the films are single-walled carbon nanotubes. In this paper, we systematically investigated the properties of the directly

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A voltage difference is detected in the “generator” part of individual water‐filled SWNTs when a current is applied on their “motor” part. It is suggested that the measured voltage difference reveals a newly induced electromotive force, which is generated by a water flow inside the SWNT. The water molecules in the nanotube channel are in turn dragged to flow by the current applied on the “motor” part.

One‐dimensional structures of nitrogen‐rich carbon nitride are synthesized via a thermal evaporation process. The CN atomic rings (s‐triazine and/or tri‐s‐triazine) present in the precursor remain stable during the thermal evaporation and vapor transfer. They act as basic building blocks during the microstructure assembly; thus ensuring a high nitrogen content in the final product.

For increasing scalability and reducing cost, transition metal dichalcogenides‐based electrocatalysts presently have been proposed as substitutes for noble metals to generate hydrogen, but these alternatives usually suffer from inferior performance. Here, a Ravenala leaf‐like WxC@WS2 heterostructure is grown via carbonizing WS2 nanotubes, whose outer walls being partially unzipped along with the Wx C “leaf‐valves” attached to the inner tubes during the carbonization process. This heterostructure exhibits a catalytic activity for hydrogen evolution reaction with low overpotential of 146 mV at 10 mA cm−2 and Tafel slope of 61 mV per decade, outperforming the performance of WS2 nanotubes and WxC counterparts under the same condition. Density functional theory calculations are performed to unravel the underlying mechanism, revealing that the charge distribution between WxC and WS2 plays a key role for promoting H atom adsorption and desorption kinetics simultaneously. This work not only provides a potential low‐cost alternative for hydrogen generation but should be taken as a guide to optimize the catalyst structure and composition.

We have directly measured the Young’s modulus and tensile strength of multiwall carbon nanotubes by pulling very long (∼2 mm) aligned nanotube ropes with a specially designed stress-strain puller. This puller can apply an axial force to the rope and simultaneously measure the corresponding rope elongation and the change in rope resistance. The average Young’s modulus and tensile strength obtained were 0.45±0.23 TPa and 1.72±0.64 GPa, respectively, which are lower than those calculated and measured previously. The factors that affect the mechanical strengths of nanotubes are discussed.

Surface energy plays an important role in surface physics, [1,2] biophysics, [3,4] surface chemistry, [5,6] and catalysis. [7] A gradient of surface energy between a solid and liquid interface can induce transport of liquids [8][9][10][11] and water running uphill, [12] which is important for DNA analysis devices.[13] Due to the 2D nature and relatively few molecules or atoms involved, the density of surface energy is usually quite small, which is impractical for utilizing surface energy as an energy source. Nevertheless it is attractive to use surface energy at the nanoscale because of the lower power consumption for nanodevices and the higher specific surface area for nanomaterials. [14][15][16][17][18] In this work, we demonstrate an effective design of single-walled carbon nanotubes (SWNTs) to harvest surface energy of ethanol and convert it into electricity. In this ethanol-burner-like design, an open-circuit voltage (V oc ) can be obtained as a result of ethanol flow in the capillary channels formed among SWNTs driven by surface tension. The V oc remains constant as long as there is ethanol from the source. The maximum power can be up to $1770 pW per device and can serve as a self-powered system to drive a thermistor. Meanwhile, the performance (the inducing rate of V oc , the value of V oc , and the output power) can be significantly enhanced by the Marangoni effect. [19] SWNTs were synthesized by floating catalytic chemical vapor deposition and treated by diamond wire drawing dies, [20][21][22] which results in well-aligned individual SWNTs (see Supporting Information S1). The resulting SWNT rope ($25.0 mm (length) Â 0.6 mm (diameter), Fig. 1a) is connected to electrodes of aluminum film, forming a suspended structure on a glass slide. The device is measured by a Keithley 4200-SCS, semiconductor characterization system, (voltage resolution 1 mV) and the dynamic characteristics of the open-circuit voltage (V oc ) are monitored while adding ethanol (MOS grade, 99.9%) to the beaker (Fig. 1b, see Supporting Information S2).In an open beaker, no obvious V oc is observed at the beginning (angle 408, Fig. 2a). When the ethanol level reaches the SWNT rope, the V oc begins to increase. The increase of V oc is almost linear from zero to 200 mV for the first 240 s, then the V oc saturates gradually at 219 mV where is remains constant over 6 h as shown in Figure 2a. V oc can remain constant as long as the ethanol level is contacting the SWNT rope. When the beaker is covered as indicated by region 2 (Fig. 2b), V oc will gradually decrease back to the original value. This process can be repeated COMMUNICATION www.MaterialsViews.com www.advmat.de Figure 1. The SWNT device and schematic layout of the experimental setup. a) An image of the device with a suspended SWNT rope. After treating with diamond wire drawing dies, the SWNT rope has a diameter of $0.6 mm and length of $25.0 mm and is connected to the electrodes. b) When measuring, the device is placed into a beaker with an angle between the SWNT rope and the ethanol ...

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