During the past decades major efforts in the field of porous materials have been directed toward control of the size, shape and uniformity of the pores. Carbide-derived carbons (CDCs) represent a new class of nanoporous carbons with porosity that can be tuned with sub-Ångström accuracy in the range 0.5-2 nm. CDCs have a more narrow pore size distribution than single-wall carbon nanotubes or activated carbons; their pore size distribution is comparable with that of zeolites. CDCs are produced at temperatures from 200-1200 o C as a powder, a coating, a membrane or parts with near-final shapes, with or without mesopores. They can find applications in molecular sieves, gas storage, catalysts, adsorbents, battery electrodes, supercapacitors, water/ air filters and medical devices. Although many carbides can be used to produce CDCs, this study was conducted on Ti 3 SiC 2 powders and bulk samples. Ti 3 SiC 2 is a soft ceramic with a lamellar structure (Supplement 1) that is commercially available and can easily be machined to any shape Four different techniques were independently used to measure the pore size: Ar, N 2 and methyl chloride, CH 3 Cl, sorption, as well as small-angle X-ray scattering (SAXS), as described in Methods. As can be seen in Fig. 1, pore sizes of CDCs increase with increasing temperature, from 0.51 nm at 300ºC, to 0.64 nm at 700ºC and 1.10 nm at 1100ºC. The sorption isotherms of low-temperature CDCs (up to 600°C) obtained using Isotherms of CDCs produced above 700°C were of type IV, which indicates the presence of mesopores. Total pore volumes observed for the samples produced at 700°, 900°, and 1100°C were almost the same, but the pore size distributions were different:Mesopore volume and size increased with increasing chlorination temperatures. Their equivalent radius was less than 3 nm at 700ºC (Fig. 1a) and about 6 nm at 1100ºC (Fig. 1b). Weight loss and energy-dispersive X-ray spectroscopy analysis of the samples after gives a very narrow peak in m(R g ) which accounts for most of the nanopore volume (Fig. 2b).SAXS confirms the aforementioned sorption data and shows that pore size can be controlled with better than 0.05 nm accuracy (Fig. 2c) -a remarkable result that has never been demonstrated for any other porous material.The interpretation of R g (Fig. 2c) With increasing temperature, the specific distance for jump of carbon atoms increases and the pore size increases accordingly. More equiaxial pores form in the 6 1000-1200ºC temperature range (Fig. 2c), which is consistent with XRD data (supplement 3) that show complete loss of interlayer correlations such that the pores no longer retain any memory of the precursor lattice.Microstructural studies of CDCs were conducted to explain their structural reorganization and the development of their porous structure with temperature. Raman spectroscopy (Fig. 3a,b) shows that carbon already forms at 200ºC. However, XRD (Fig. 3e). Noticeable ordering of graphite starts at 700ºC (Fig. 3d) and nanocrystalline graphite appears at 1200ºC (...

The creation of continuous nanoscale composite fibrils from carbon nanotubes using an electrospinning process is reported. Nanotube bundles align in the fiber, and upon heat treatment, the composite fibrils are carbonized at 1100 °C to form the SWNT/carbon yarns. The fibrils show superior mechanical properties and can be used as a reinforcement for a variety of materials.

We describe a simple and versatile technique to produce magnetic tubes by filling carbon nanotubes (CNTs) with paramagnetic iron oxide particles ( approximately 10 nm diameter). Commercial ferrofluids were used to fill CNTs with an average outer diameter of 300 nm made via chemical vapor deposition into alumina membranes. Transmission electron microscopy study shows a high density of particles inside the CNT. Experiments using external magnetic fields demonstrate that almost 100% of the nanotubes become magnetic and can be easily manipulated in magnetic field. These one-dimensional magnetic nanostructures can find numerous applications in nanotechnology, memory devices, optical transducers for wearable electronics, and in medicine.

We present a method to fill 2−5-nm-diameter channels of closed multiwalled carbon nanotubes (MWNT) with an aqueous fluid and perform in situ high-resolution observations of fluid dynamic behavior in this confined system. Transmission electron microscope (TEM) observations confirm the successful filling of two types of MWNTs and reveal disordered gas/liquid interfaces contrasting the smooth curved menisci visualized previously in MWNT with diameter above 10 nm. Electron energy loss spectroscopy (EELS) and energy dispersive spectrometry (EDS) analyses, along with TEM simulation, indicate the presence of water in MWNT. A wet−dry transition on the nanometer scale is also demonstrated by means of external heating. The results suggest that when ultrathin channels such as carbon nanotubes contain water, fluid mobility is greatly retarded compared to that on the macroscale. The present findings pose new challenges for modeling and device development work in this area.