Upon laser irradiation in air, metallic single-walled carbon nanotubes (SWNTs) in carbon nanotube thin film can be destroyed in preference to their semiconducting counterparts when the wavelength and power intensity of the irradiation are appropriate and the carbon nanotubes are not heavily bundled. Our method takes advantage of these two species' different rates of photolysis-assisted oxidation, creating the possibility of defining the semiconducting portions of carbon nanotube (CNT) networks using optical lithography, particularly when constructing all-CNT FETs (without metal electrodes) in the future.
The hydrogen storage capacity of five types of commercially available carbon materials with different nanostructures was measured at up to 8 MPa at room temperature using an apparatus based on a volumetric method with an error of less than 0.04 wt %/gr. The highest storage capacity of 0.43 wt % was obtained for purified HiPco™ single-walled carbon nanotubes (SWNTs). In the SWNTs, the hydrogen density in pores with a diameter of less than 1 nm was estimated to be a 0.022 g/ml, which corresponds to 31% of the density of liquid hydrogen. Issues in the development of carbon-based hydrogen storage media are discussed.
Transparent single‐walled carbon nanotube (SWNT) films have their conductivity optimized by a multistep purification method and by the construction of a sandwich structure with chemical modification. The transparent and conducting SWNT films demonstrate great potential for applications in optoelectronic devices.
Natural polyelectrolytes (NPs), including sodium lignosulfonate, humic acid and so
forth, are reported for the first time to solubilize single-walled carbon nanotubes
(SWNTs) in water through a noncovalent interaction. A variety of methods, including
transmission electron microscopy (TEM), visible–near-infrared (vis–NIR) spectra,
Raman spectra and zeta potential measurements, were used to characterize the
NP-dispersed SWNT solutions. It is found that the SWNTs can be exfoliated
into thin bundles or individual tubes, even at NP concentrations as low as
0.15 mg ml−1. Their high performance is attributed to the abundance of aromatic groups and ionized
groups in the NP molecules. This method of solubilization opens the way for exploiting new
natural materials as SWNT solubilizers and may find applications in nanocomposites,
self-assembly, and so forth.
High-quality double-walled carbon nanotube (DWNT) super bundles were selectively grown above a bowllike cathode by arc discharge in a hydrogen-free atmosphere. These DWNTs can resist high-temperature (up to 720°C) oxidation in air without additional annealing even after acid treatment, which is due to an in-situ defect-healing effect of the bowl-like cathode and the absence of reactive gases during arc discharge. Selective formation of DWNTs is ascribed to the increased presence of carbon clusters in the enlarged hot plasma region inside the cathode and optimized composition of the catalysts.
Single‐walled carbon nanotubes (SWNTs) are a promising material for future nanotechnology. However, their applications are still limited in success because of the co‐existence of metallic SWNTs and semiconducting SWNTs produced samples. Here, electrochemical etching, which shows both diameter and electrical selectivity, is demonstrated to remove SWNTs. With the aid of a back‐gate electric field, selective removal of metallic SWNTs is realized, resulting in high‐performance SWNT field‐effect transistors with pure semiconducting SWNT channels. Moreover, electrochemical etching is realized on a selective area. These findings would be valuable for research and the application of SWNTs in electrochemistry and in electronic devices.
We report an improvement in oxidation resistance of single-walled carbon nanotubes (SWNTs) produced by arc discharge in a bowl-like
cathode. The Raman spectrum of the new arc-discharge SWNTs shows a significant enhancement in the G/D (∼1590:∼1350 cm-1) ratio,
suggesting that cleaner and less defective SWNTs are generated by the new arc-discharge method compared to the conventional arc-discharge
method. These changes are further confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Production
of improved SWNTs with better oxidation resistance is mainly ascribed to the in-situ annealing effect of the bowl-like cathode.
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