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Recently, two-dimensional tungsten disulfide (WS2) has attracted attention as a next generation thermoelectric material due to a favorable Seebeck coefficient. However, its thermoelectric efficiency still needs to be improved due to the intrinsically low electrical conductivity of WS2. In the present study, thermoelectric properties of WS2 hybridized with highly conductive single-walled carbon nanohorns (SWCNHs) were investigated. The WS2/SWCNH nanocomposites were fabricated by annealing the mixture of WS2 and SWCNHs using a high-frequency induction heated sintering (HFIHS) system. By adding SWCNHs to WS2, the nanocomposites exhibited increased electrical conductivity and a slightly decreased Seebeck coefficient with the content of SWCNHs. Hence, the maximum power factor of 128.41 &mu, W/mK2 was achieved for WS2/SWCNHs with 0.1 wt.% SWCNHs at 780 K, resulting in a significantly improved thermoelectric figure of merit (zT) value of 0.027 compared to that of pristine WS2 with zT 0.017.

MXene and graphene based thin, flexible and low-density composite were prepared by cost effective spray coating and solvent casting method. The fabricated composite was characterized using Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX). The prepared composites showed hydrophobic nature with higher contact angle of 126&deg, &minus, 43 mN&middot, m&minus, 1 wetting energy, &minus, 116 mN&middot, 1 spreading Coefficient and 30 mN&middot, 1 lowest work of adhesion. The composites displayed excellent conductivity of 13.68 S&middot, cm&minus, 1 with 3.1 &Omega, &middot, sq&minus, 1 lowest sheet resistance. All the composites showed an outstanding thermal stability and constrain highest weight lost until 400 &deg, C. The MXene-graphene foam exhibited excellent EMI shielding of 53.8 dB (99.999%) with reflection of 13.10 dB and absorption of 43.38 dB in 8&ndash, 12.4 GHz. The single coated carbon fabric displayed outstanding absolute shielding effectiveness of 35,369.82 dB&middot, cm2&middot, g&minus, 1. The above results lead perspective applications such as aeronautics, radars, air travels, mobile phones, handy electronics and military applications.

This paper investigated the fracture behavior of the unavoidable breakage of carbon fibers and fiber orientation of short carbon fiber reinforced polycarbonate composite in injection process. In this experiment, short carbon fiber mixed compound of 1mm, 3mm, 5mm, 7mm length with 10wt.%, 15wt.%, 20wt.% in polycarbonate for injection molding were produced through the extruder. The dumbbell specimens for tensile evaluation were made by injection molding. The parent specimens were made by double gate method, the weld specimens were made by single gate method which was controlled by inserting a stopper through the runner of the mold cavity. Short carbon fiber reinforced PC composite was evaluated by micro-CT with regard to the particle size of short fiber with a diversified quantitative analysis through entire process of the injection process in composite. The quantitative distribution of fiber orientation was also examined by micro-CT with regard to normal direction or anisotropy. Weld line of short carbon fibers reinforced PC composite weaken the bonding strength by 50% compared to parent materials because the weld line is composed with concentrated anisotropy orientation of short carbon fiber in weld line. Evaluation of the mechanical properties of the injection specimens group was utilized by universal tensile strength tester. In addition, fracture surface of parent and weld materials was investigated by a SEM.

Nanoporous carbons, with different micropore size distributions, were prepared based on waste coffee grounds by a chemical activation process in order to elucidate the correlation between desolvated ions and pores smaller than the sizes of ions using an organic electrolyte. The pore structure of the coffee-based nanoporous carbon was strongly dependent on the heat-treatment temperature prior to the activation process. Cyclic voltammograms of the nanoporous carbons mainly dominated by the smaller pore relative to that of the bare ion size clearly showed deviation from an ideal feature of the current response. It was clearly envisaged that even a bare ion of a size larger than the pore size can penetrate into the pore by voltage-induced force.

Environmentally benign natural amino acids, especially histidine-derived nitrogen-doped carbon materials were readily synthesized from polycondensation reaction and subsequent carbonization via the stepwise thermolysis process with high yields of ~40% even at a high temperature of 1000 °C and the nitrogen-atom contents of around 5 wt%. These materials possessed rolled planar structures as well as thick 2D-like planar structures with specific surface area of 455 m2/g, exhibiting a notable specific capacitance of 58 F/g at current densities of 0.1 A/g and superior stability without deterioration of performance values up to 2000 cycles.

In the last decades, carbon fibers with light weight and high strength have experienced the largely increased uses in various industrial applications. However, their expected uses in the automotive industry and building are largely limited because of their high production cost. Herein, we have demonstrated an effective method of making low cost carbon fibers via the melt spinning of petroleum-processing residue (pyrolyzed fuel oil, PFO)/lignin blends. Careful selection of tetrahydrofuran as the solvent to dissolve both PFO and lignin was made to optimize the miscible blend. The melt spinnable blend with a softening point of 260–280 °C exhibited good spinning ability at 280 °C. The plasticizing function of PFO allowed the highly cross linked lignin-based pitch to have high fluidity in the melt spinning process. Based on detailed TEM observations, the thermally treated fiber prepared at 2800 °C exhibited a shell–core structure, consisting of a highly crystalline surface from PFO and an amorphous disordered core from lignin. Such a crystalline surface structure gave rise to a high modulus value (up to 100 GPa) to the prepared carbon fibers.

We explore the importance of the size and position of nanoholes on the electrochemical performance of single-walled carbon nanohorn (SWCNH)-based supercapacitors using an ionic liquid electrolyte. The oxidized sample at 673 K showed a low specific capacitance per unit of internal specific surface area (4.0 μF cm–2), as the nanoholes created on the tips of SWCNHs via a selective chemical attack are too small to introduce electrolyte ions. For a sample oxidized at 723 K, the enlarged diameter of the nanoholes on the tips allows electrolyte ions to penetrate into the internal spaces of the SWCNHs, thereby resulting in a 2-fold capacitance improvement (8.6 μF cm–2). However, the abrupt decrease in the capacitance of the oxidized SWCNHs at 823 K (3.8 μF cm–2) can be explained by the selective formation of nanoholes on the sidewalls of the SWCNHs, where the small interstitial pores restrict ion diffusion to deeply positioned nanoholes on the sidewalls of the SWCNHs. Our study clearly reveals that the size and p...

It has become critically important to develop reliable method to transfer chemical vapor deposited (CVD) graphene from its growth substrate to the target substrate without leaving undesired polymer residues on the graphene surface. Here, we have found that for the two different transfer method – wet transfer using poly(methyl methacrylate) (PMMA) and dry transfer using polydimethylsiloxane (PDMS) as support layer, the amount of polymer residues and other impurities left on the graphene surface varies depending on the solvent used to remove those polymers. The exposure of the graphenes to different organic solvents such as acetone and chloroform resulted in different amount of polymer residues and impurities present on the graphene surface, which impact the electronic structure of the transferred graphene. It was found that the graphene obtained using the dry transfer method and acetone as solvent with a 2D to G (I2D/IG) intensity ratio of 4.58 and a 2D peak full width-half maximum (FWHM) of 24.66, which was higher than that using the wet transfer method and chloroform as solvent. These results showed that graphene was less affected by the polymer residues and impurities or the dry transfer method rather than the wet transfer method. In addition, using acetone rather than chloroform as solvent in the dry transfer method led to less contaminated graphene.

Carbon fibers are considered as one of the promising heating elements in various industrial applications because of their excellent thermal stability and electrical conductivity. In order to achieve controllability of the power output, gas-phase carbon deposition was carried out on the surface of carbon fibers by flowing a mixture of liquefied petroleum gas and hydrogen via electro-conduction chemical vapor deposition. We confirmed the tuning ability of the temperature ranging from 800 to 1330 °C. The microtexture of the deposited carbon was sequentially changed; the initial layer with small-sized domains, the intermediate layer with medium crystallinity, and the top layer with large-sized domains and high crystallinity. However, the linear decrease in the electrical conductivity of the heating elements was ascribed to the change in the growing direction of the crystallites from a longitudinal to a perpendicular direction with respect to the fibers. The wide range of power output for our carbon fiber composites from 270 to 448 W at 50 V will be useful for various industrial electric heating applications.

A series of multi-walled carbon nanotube (MWCNT) coated carbon fabrics was fabricated using a facile dip coating process, and their performance in electrical conductivity, thermal stability, tensile strength, electromagnetic interference (EMI) and shielding effectiveness (SE) was investigated. A solution of MWCNT oxide and sodium dodecyl sulfate (SDS) in water was used in the coating process. MWCNTs were observed to coat the surfaces of carbon fibers and to fill the pores in the carbon fabric. Electrical conductivity of the composites was 16.42 S cm−1. An EMI shielding effectiveness of 37 dB at 2 GHz was achieved with a single layer of C/C composites, whereas the double layers resulted in 68 dB EMI SE at 2.7 GHz. Fabricated composites had a specific SE of 486.54 dB cm3 g−1 and an absolute SE of approximately 35,000 dB cm2 g−1. According to the above results, MWCNT coated C/C composites have the potential to be used in advanced shielding applications such as aerospace and auto mobile electronic devices.

Here, we show that chemical vapor deposition growth of graphene on copper foil is strongly affected by the cooling conditions. Variation of cooling conditions such as cooling rate and hydrocarbon concentration in the cooling step has yielded graphene islands with different sizes, density of nuclei, and growth rates. The nucleation site density on Cu substrate is greatly reduced when the fast cooling condition was applied, while continuing methane flow during the cooling step also influences the nucleation and growth rate. Raman spectra indicate that the graphene synthesized under fast cooling condition and methane flow on cool-down exhibit superior quality of graphene. Further studies suggest that careful control of the cooling rate and CH4 gas flow on the cooling step yield a high quality of graphene.

Nanoscale defects in the outer tube to preserve the electrical and optical features of the inner tube can be engineered to exploit the intrinsic properties of double walled carbon nanotubes (DWCNTs) for various promising applications. We demonstrated a selective way to make defects in the outer tube by the fluorination of DWCNTs followed by the thermal detachment of the F atoms at 1000 °C in argon. Fluorinated DWCNTs with different amounts of F atoms were prepared by reacting with fluorine gas at 25, 200, and 400 °C that gave the stoichiometry of CF 0.20 , CF 0.30 , and CF 0.43 , respectively. At the three different temperatures used, we observed preservation of the coaxial morphology in the fluorinated DWCNTs. For the DWCNTs fluorinated at 25 and 200 °C, the strong radial breathing modes (RBMs) of the inner tube and weakened RBMs of the outer tube indicated selective fluorine attachment onto the outer tube. However, the disappearance of the RBMs in the Raman spectrum of the DWCNTs fluorinated at 400 °C showed the introduction of F atoms onto both inner and outer tubes. There was no significant change in the morphology and optical properties when the DWCNTs fluorinated at 25 and 200 °C were thermally treated at 1000 °C in argon. However, in the case of the DWCNTs fluorinated at 400 °C, the recovery of strong RBMs from the inner tube and weakened RBMs from the outer tube indicated the selective introduction of substantial defects on the outer tube while preserving the original tubular shape. The thermal detachment of F atoms from fluorinated DWCNTs is an efficient way to make highly defective outer tubes for preserving the electrical conduction and optical activity of the inner tubes.

Polyimide (PI)-based nanocomposites containing aminophenyl functionalized multiwalled carbon nanotubes (AP-MWCNTs) obtained through a diazonium salt reaction was successfully prepared by in situ polymerization. PI composites with different loadings of AP-MWCNTs were fabricated by the thermal conversion of poly(amic acid) (PAA)/AP-MWCNTs. The mechanical and electrical properties of the AP-MWCNTs/PI composites were improved compared with those of pure PI due to the homogeneous dispersion of AP-MWCNTs and the strong interfacial covalent bonds between AP-MWNTs and the PI matrix. The conductivity of AP-MWNTs/PI composites (5:95 w/w) was 9.32 × 10−1 S/cm which was about 1015 times higher than that of Pure PI. The tensile strength and tensile modules of the AP-MWCNTs/PI composites with 0.5 wt % of AP-MWCNTs were increased by about 77% (316.9 ± 10.5 MPa) and 25% (8.30 ± 1.10 GPa) compared to those of pure PI, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 960–966

Carbon nanotubes have shown great potential as conductive fillers in various composites, macro-assembled fibers, and transparent conductive films due to their superior electrical conductivity. Here, we present an effective defect engineering strategy for improving the intrinsic electrical conductivity of nanotube assemblies by thermally incorporating a large number of boron atoms into substitutional positions within the hexagonal framework of the tubes. It was confirmed that the defects introduced after vacuum ultraviolet and nitrogen plasma treatments facilitate the incorporation of a large number of boron atoms (ca. 0.496 atomic %) occupying the trigonal sites on the tube sidewalls during the boron doping process, thus eventually increasing the electrical conductivity of the carbon nanotube film. Our approach provides a potential solution for the industrial use of macro-structured nanotube assemblies, where properties, such as high electrical conductance, high transparency, and lightweight, are extremel...

We have experimentally and theoretically clarified the effect of oxygen functional groups on the capacitive performance of a photochemically treated activated carbon electrode. A high density of CO groups at the mouth of the micropores, where the chemically active edge sites are predominantly available, increases the energy barrier for ions to enter the pores, thereby resulting in a large decrease in the specific capacitance.

Porous carbon nanofibers (PCNFs) were prepared from electrospinning both without and with a pore generating inorganic material. Next, they were activated with different activation media (N2, H2O, or CO2). The pore size was tailored from 0.64 to 0.81 nm under various activation conditions, and the specific surface area ranged from 404 to 1624 m2·g−1. To determine the charging mechanism of the supercapacitor in an aqueous electrolyte, the normalized capacitance was calculated, and it was compared with the adsorption behavior of the solvent, H2O, separately. The normalized capacitance showed a trend similar to that of H2O adsorption at a low relative pressure (P/P0 = 0.1), which was expected to be driven by the filler–pore wall interaction, indicating that the ions were strongly solvated by the solvent, H2O. The highest normalized capacitance value (32 μF·cm−2 at 1 mA·cm−2) was achieved from PCNFs having a pore size of 0.64 nm, similar to the electrolyte solvated ion sizes. It was observed that both the capacitance and H2O adsorption were achieved near the pore size of 0.64 nm and at a high functionality. It was understood that the adsorption of the solvated ions was primarily driven by the interaction of the solvent, H2O, with the surface functional groups.

An efficient strategy for the enhancement of mechanical properties of carbon nanotube (CNT) fibers is developed using functionalized graphene oxide with a quaternary ammonium (QA) group (QA-FGO). QA-FGO is designed to induce the π-cation interaction, one of the strongest interactions in living systems, with CNT fibers. Based on the strategy, the tensile strength (58 MPa), specific strength (0.49 N/tex), modulus (2.5 GPa) and toughness (1.1 MJ/m3) of CNT fibers are enhanced to 409 MPa, 0.65 N/tex, 13.4 GPa, and 10.1 MJ/m3, respectively. The reinforcement mechanism is systematically demonstrated with experimental and theoretical approaches.

We investigated the importance of the specific effective surface area through a detailed study on the relationship between electrical conductivity of single-walled carbon nanohorns (SWCNHs) and accessibility of the electrolyte ions in the SWCNH-based supercapacitor. After heat treatment of the SWCNHs, the ratio of sp2/sp3 carbons dramatically increased, suggesting an enhanced electrical conductivity of the SWCNHs. Even though the specific surface area (SSA) slightly decreased by 16% as a result of heat treatment, the specific capacitance per SSA of the SWCNH electrode remarkably increased from 22 to 47 μF cm–2. Such a result indicates an explicit increase in accessible effective surface area by electrolyte ions. Our result clearly showed that a higher degree of utilization for the interstitial pore of SWCNHs by solvated ions is a key factor in achieving a high volumetric capacitance of SWCNH-based supercapacitors.

Flexible transparent conducting films (TCFs) were fabricated by dip-coating single-wall car- bon nanotubes (SWCNTs) onto a flexible polyethylene terephthalate (PET) film. The amount of coated SWCNTs was controlled simply by dipping number. Because the performance of SWCNT-based TCFs is influenced by both electrical conductance and optical transmittance, we evaluated the film performance by introducing a film property factor using both the number of interconnected SWCNT bundles at intersection points, and the coverage of SWCNTs on the PET substrate, in field emission scanning electron microscopic images . The microscopic film property factor was in an excellent agreement with the macroscopic one determined from electrical conductance and optical transmittance measurements, especially for a small number of dippings. Therefore, the most crucial factor governing the performance of the SWCNT-based TCFs is a SWCNT-network structure with a large number of intersection points for a minimum amount of deposited SWCNTs.

The hydrothermal synthesis behavior of ZnO nanowire (NW) on carbon nanotubes (CNTs) with respect to molar concentrations of zinc nitrate hexahydrate and hexamethylenetetramine and temperature was investigated. The ZnO NWs could be synthesized with a single-crystalline wurtzite structure and a diameter in the range of tens of nanometers. Their size does not strongly depend on the temperature, while it increases with increasing molar concentration. The NWs tend to have pyramidal shape at a growth front with increasing temperature and molar concentration probably due to enriched Zn2+ ion concentration. This demonstrates the morphological dependence of ZnO NWs on the relative rates between the decomposition of Zn precursor and subsequent oxidation of Zn to ZnO in hydrothermal synthesis.

Poly(vinylidene chloride) (PVDC)-derived nanoporous carbons were prepared by various activation methods: heat-treatment under an inert atmosphere, steam activation, and potassium hydroxide (KOH) activation at 873, 1073, and 1273 K. The pore structures of PVDC-derived nanoporous carbons were characterized by the N 2 adsorption technique at 77 K. Heat treatment in an inert atmosphere increased the specific surface area and micropore volume with elevating temperature, while the average micropore width near 0.65 nm was not significantly changed, reflecting the characteristic pore structure of ultramicroporous carbon. Steam activation for PVDC at 873 and 1073 K also yielded ultramicroporosity. On the other hand, the steam activated sample at 1273 K had a wider average micropore width of 1.48 nm, correlating with a supermicropore. The KOH activation increased the micropore volume with elevating temperature, which is accompanied by enlargement of the average micropore width from 0.67 to 1.12 nm. The average pore widths of KOH-activated samples were strongly governed by the activation temperature. We expect that these approaches can be utilized to simply control the porosity of PVDC-derived nanoporous carbons.

Supercapacitors can store and deliver energy by a simple charge separation, and thus they could be an attractive option to meet transient high energy density in operating fuel cells and in electric and hybrid electric vehicles. To achieve such requirements, intensive studies have been carried out to improve the volumetric capacitance in supercapacitors using various types and forms of carbons including carbon nanotubes and graphenes. However, conventional porous carbons are not suitable for use as electrode material in supercapacitors for such high energy density applications. Here, we show that edge-enriched porous carbons are the best electrode material for high energy density supercapacitors to be used in vehicles as an auxiliary powertrain. Molten potassium hydroxide penetrates well-aligned graphene layers vertically and consequently generates both suitable pores that are easily accessible to the electrolyte and a large fraction of electrochemically active edge sites. We expect that our findings will motivate further research related to energy storage devices and also environmentally friendly electric vehicles.

The supercritical H2 adsorption property of single-walled carbon nanotube (SWCNT) bundles irradiated by a 300 keV electron beam was studied with aspects of structural deformations and morphological changes in defect SWCNT bundles. Electron irradiation may extract the carbon atoms from the lattice surface of the SWCNT bundles, producing a lot of dangling bonds. Random rebonding of the dangling bonds causes the shrinkage of the SWCNTs, and also, it increases the intertube linkage, reducing the micropore volume and the H2 adsorption amount per unit mass. Meanwhile, the shrinkage of the SWCNT dramatically promotes the H2 adsorptivity due to narrower micropores having a stronger interaction potential for H2.

The importance of nanopore structures of carbons is shown in terms of interaction potential for various molecules including supercritical gases such as and . The key factors for adsorption of supercritical and are shown for single wall carbon nanohorn, single wall carbon nanotube, and double wall carbon nanotube. The cluster formation of molecules is a key process for water adsorption on hydrophobic carbon nanopores. The X-ray absorption spectroscopic examination elucidates an explicit dehydration structure of ions confined in carbon nanopores.

Single wall carbon nanotubes (SWCNTs) were treated with a HNO3/H2SO4 mixed solution to increase the number of narrow micropores. The mixed acid treatment increased the micropore volume from 0.13 to 0.35 mL g−1 as measured by N2 adsorption at 77 K. The micropore volume evaluated with CO2 adsorption at 273 K increased from 0.06 to 0.27 mL g−1. This remarkable micropore volume increase was ascribed to the formation of a highly packed and ordered SWCNT assembly with the acid treatment, which was confirmed by field emission scanning electron microscopy. The adsorption amount of supercritical H2 at 77 K under 5 MPa pressure increased twofold as a result of the acid treatment, while the supercritical CH4 adsorption amount at 303 K and 5 MPa pressure increased by 40%. These remarkable increases were caused by increased amount of narrow micropores as a result of the acid treatment.

Single wall carbon nanotube (SWCNT), which has bundle structure and entangled structure, was untangled and cut by sonication in hydrogen peroxide (H2O2) solution. The untangled state of SWCNT was examined by SEM, TEM, Raman spectroscopy and N2 adsorption. It was confirmed that the surface area of sonicated nanotubes strongly depended on the sonication time. The BET specific surface area (SSA) of nanotubes sonicated for 3 h was maximum. The SSA decreased at 6 h or more of sonication time. These results indicated that the bundle structure was untangled and the cap of SWCNT was opened. Thus, N2 molecules can access the most efficiently inside of the SWCNT sonicated for 3 h. On the contrary, the sonication treatment for 6 h or more decomposed the nanotubes to produce amorphous carbon, evidenced by TEM and SEM observation; the amorphous carbon blocked the open pore sites such as the internal pore spaces and interstitial pores.

This paper proposes a new semi-rigid detail used high-strength bolts for use in earthquake resistant structures. These specimens were single-side beam-to-column assemblies that are representative of exterior beam-to-column connections, and they were composed of identical beam and column but had the different connection details, respectively. All beam-to-column assembly required no welding. Specimen 1 (TSD) was standard Top-Seat-Double-web-angle but specimen 2 (MTSD) was made by modified shape. Two high-strength bolted steel semi-rigid connections were prepared and cyclic load was applied to each test specimen using displacement control. The cyclic load and displacements, moment-rotation plots, and the deformation pattern or failure modes for all the test cases are presented. The strength, stiffness, energy, and ductility of the tested connections are compared to each other.

This paper presents an experimental work on the cyclic behavior of bolted and welded beam-to-column connections in steel portal frame. Three types of connection were used; tests for each specimen were performed twice in order to maintain test reliability. Specimen 1 (DWA) had only a double web angle connection, specimen 2 (TSD) had a top and seat angles with double web angle connection, and specimen 3 (FW) had a fully welded connection. All specimens were tested under cyclic loading conditions in order to simulate the effects of earthquakes. We also conclude that with appropriate design and careful consideration of connection strength and stiffness, the steel project economy may be maximized.

An appropriate choice of building shape and architectural modifications can result in the reduction of motion by altering the flow pattern around a building. Tapering which is one of aerodynamic devices has been known to be effective to reduce acrosswind response [1, 2]. The exterior wind loading patterns on claddings are sensitive to the building shape. When a building has a tapered cross section along the height, the influence of the exterior wind loading patterns on the wind-induced high-cycle fatigue damage of the cladding fastener of the tapered building needs to be found. In this study, the fatigue damage of the cladding fastener of a non-tapered building and two tapered buildings is estimated by using the rainflow cycle counting method and Miner’s rule. The fatigue damage is compared with one another in order to investigate the influence of the tapered cross section on the fatigue damage of cladding fasteners on side faces of tall buildings

Extensive experimental, analytical and design studies in the recent past have been undertaken on the behavior of joint which has a direct influence on the stability of steel frame. Few experimental studies on the joint, however, have been carried out to compare between the behavior of sub-assemblages with high-strength bolted and welded joints. Therefore, this paper presents an experimental investigation on the cyclic behavior of the steel sub-assemblages with fully welded (FW) and high-strength bolted joints (TSD and DWA). This study consisted of subjecting three joint specimens to an increasing level of large cyclic rotations until failure occurred. The main objectives of this study focus on the cyclic behavior of steel specimens with bolted joints in comparison with welded joint. The test results show that the high-strength bolted joints (TSD and DWA) used in this study developed, respectively, about 39% and 4.4% for initial stiffness and about 28.3% and 58.6% for ultimate moment obtained from the moment–rotation relationship, when compared with that of the welded joint. Based on the experimental results of this study, the following characteristics have to be revealed: mechanism of failure (failure mode), elastic limit (yield point), ultimate moment, ductility, energy dissipation and so on.

The radial breathing mode (RBM) frequency in Raman spectra of single-wall carbon nanotubes (SWNTs) is upshifted (3−9 cm-1) by immersion of the SWNTs in various alcohols and water. However, the immersion in the solvents does not cause any visible variation in the tangential mode frequency. The degree of this RBM frequency upshift induced by the solvent adsorption corresponds to that caused by applying a high pressure of 1 GPa (6−10 cm-1/GPa) in the literature. The degree of the RBM frequency upshift increases with increases in the molecular weight of the solvents. RBM frequency upshift caused by immersion of SWNTs in water is much larger than that by the molecular weight of alcohols, indicating the cluster formation of water molecules.

We have reported the density-functional calculations of NO2 adsorption on single-walled carbon nanotube (SWCNTs) walls. We find that NO2 adsorption is strongly electronic structure- and strain-dependent. The NO2 adsorption on metallic nanotubes (m-SWCNTs) was energetically more favorable than that on semiconducting nanotubes (s-SWCNTs) and furthermore the adsorption became less stable with increasing diameters of nanotubes. The adsorption barrier height shows similar dependence on the electronic structure and diameter to the adsorption energy. On the base of our theoretical model, we have found a method for a diameter-selective removal of metallic single-walled carbon nanotubes (m-SWCNTs) from semiconducting (s-) ones by stirring or sonication SWCNT powder in tetramethylene sulfone (TMS)/chloroform solution with nitronium hexafluoroantimonate (NO2SbF6: NHFA) and nitronium tetrafluoroborate (NO2BF4: NTFB). Positively charged nitronium ions were intercalated into nanotube bundles, where the intercalation was promoted also by the counter ions. Nitronium ions selectively attacked the sidewall of the m-SWCNTs due to the abundant presence of electron density at the Fermi level, thus yielding stronger binding energy compared to the counterpart s-SWCNTs. The s-SWCNTs were left on the filter after filtration, whereas the m-SWCNTs were disintegrated and drained away as amorphous carbons. The effectiveness of removing m-SWCNTs was confirmed by the resonant Raman spectra and absorption spectra.

A simple and robust dip-coating method for fabricating carbon nanotube (CNT) field emitters has been proposed. The thin multiwalled (tMW)CNTs synthesized by CVD were dispersed in various solutions such as N,N-dimethylformamide (DMF), isopropyl alcohol (IPA), N-methyl-2-pyrrolidinone (NMP), and dichloroethane (DCE). The weak adhesion between CNTs and substrate, a serious drawback of the dip-coating approach, was resolved by anchoring CNTs to the substrate via the melting of an indium layer. We found that the uniformity and density of the CNTs could be optimized by controlling the degree of dispersion of CNTs in solvents. The field-emission characteristics are also discussed.

Densely packed assemblies of single-walled carbon nanotubes (SWCNTs) were characterized by N2 and CO2 adsorption techniques. We presented a convenient method for forming densely packed assembly structures of SWCNTs. The SWCNTs were treated with mixtures of HNO3/H2SO4 or H2O2/H2SO4 before and after purification, to control the packing density and porosity of the SWCNT samples. H2O2/H2SO4 treatment caused a dramatic increase in microporosity without significantly changing the mesoporosity, whereas HNO3/H2SO4 treatment decreased the mesoporosity and simultaneously increased the microporosity. This reduced mesoporosity originates from the contraction of the interbundle distance of SWCNTs. After HNO3/H2SO4 treatment of the purified SWCNTs, the micropore surface area increased about 8.6 times compared to the pristine sample, and the volume fraction of the micropores increased from 10% to 91%, indicating formation of densely packed assemblies of SWCNTs. Therefore, HNO3/H2SO4 treatment could control not only the ...

Thin multi-walled carbon nanotubes (t-MWCNTs) synthesized by catalytic chemical vapor deposition were characterized by transmission electron microscopy (TEM), Raman spectroscopy, and gas adsorption. TEM observations showed that the innermost diameter ranges from less than 1 to 5 nm and the outermost diameter ranges from 4 to 12 nm, which are much smaller than conventional thick MWCNTs. We observed clear radial breathing modes in Raman spectra, which are attributed to the existence of inner nanotubes in small diameters less than 3 nm. We also performed N2 adsorption at 77 K after the tip opening of t-MWCNTs by nitric acid in order to analyze the tube inner diameters. The pores with sizes less than 4 nm corresponding to the inner empty space of t-MWCNTs were largely developed, in good agreement with TEM and Raman observations. 2005 Elsevier B.V. All rights reserved.

In this paper we present a simple approach of nanodispersing single-walled carbon nanotubes (SWCNTs) in a non-polar 1,2-dichloroethane (DCE) solvent. After filtration with isopropanol and acetone, the purified SWCNTs were immersed in DCE, followed by sonication for about 15 hours. The samples were further centrifuged at 17,000 revolutions per minute for about 3 hours. Atomic force microscopy (AFM) demonstrated that the spin-coated nanotubes were mostly individual nanotubes with an average diameter of 1.6 nm and a length of about 250 nm. We also found that the presence of water, and the dry process during DCE treatment, prevented nanotubes from being nanodispersed.

The formation of a massive quantity of single-wall carbon nanotube (SWCNT) superbundles has been introduced through sonicating SWCNTs in tetramethylene sulfone/chloroform solution in which nitronium hexafluoroantimonate (NHFA) is dissolved. Most SWCNT bundles with the NHFA treatment are enlarged by about 10 times compared with those of the pristine sample. It is proposed that the formation of SWCNTs can occur in solution by formation of an SWCNT-intercalant charge complex. The specific surface area of the superbundle is almost doubled, while its micropore surface area is amplified by about 7 times. This development of microporosity results from the enhanced interstitial sites in the SWCNT superbundles.

In this paper, we report two metal-organic frameworks [Co 3 (ndc) 3 -(bipyen) 1 5 ].H 2 O (1) and [Co 2 (ndc) 2 (bipyen)].C 6 H 6 .H 2 O (2) (bipyen = trans-1,2-bis(4-pyridyl)ethylene, H 2 ndc=2,6-naphthalenedicarboxylic acid). These compounds were both synthesized from identical hydrothermal reaction conditions except that benzene was added to the reaction for 2. Crystal structures show that the two compounds have triply interpenetrated three-dimensional frameworks and these frameworks have the same primary structure of a two-dimensional network of interconnected [Co 2 -(O 2 CR) 4 / 2 ] (R=naphthalene group) paddle-wheels and bridging bipyen ligands. Both compounds have guest water molecules and, in addition, 2 has guest benzene molecules. Structural transformations of the host accompanied guest removal, which can be monitored by powder X-ray diffraction. N 2 adsorption data of 2 show that there are two different types of pores corresponding to the benzene and water pores. Upon exposure to vapors of several organic molecules, the heat-treated sample of 2 adsorbs benzene and cyclohexene, but does not adsorb toluene, (o-, m-, and p-)xylenes, cycloheptatriene, or cyclohexane.

Single-wall carbon nanohorns (SWNHs) with dahlia flowerlike structures were treated with H2SO4 and H2O2/H2SO4 mixture. The SWNH samples before and after acid treatment were characterized using a transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, temperature-programmed desorption (TPD), and N2 adsorption at 77 K. According to TEM and SEM observation, the SWNH bundles were coalesced after H2SO4 and H2O2/H2SO4 treatments, growing up to the bundle size of several micrometers. The Raman spectra provided evidence that the H2O2/H2SO4 treatment leads to intercalation of the H2SO4 molecule into interstitial spaces of individual SWNHs as well as defect formation by oxidation reaction. The H2O2/H2SO4 treatment also altered markedly the N2 adsorption isotherms of SWNH from type II to type I, accompanied with an enhanced N2 adsorption uptake at low relative pressure due to the development of microporosity. Heat treatment at 873 K on H2O2/H2SO4-treated SWNHs additionally inc...

The effects of nitrogen-doping on adsorption properties of activated carbon fibers (ACFs) for NO were investigated. The nitrogen-doped ACFs (N-ACFs) were prepared by chemical vapor deposition (CVD) of pyridine at 1023 K for various times. The N-ACFs were characterized by N2 adsorption at 77 K, elemental analysis, and X-ray photoelectron spectroscopy (XPS). The nitrogen content increases with the pyridine-CVD time. An XPS examination showed that the fraction of quaternary nitrogen in the nitrogen structures is almost constant, regardless of the CVD times. However, quaternary nitrogen increases remarkably from 54% to 78% after heat-treatment of N-ACF at 1273 K, although the total nitrogen content decreases. The adsorption properties of N-ACFs for NO were examined at 303 K. The NO adsorption capacity of N-ACFs increases with the concentration of doped nitrogen. The NO adsorptivity of the N-ACF was remarkably enhanced by the heat-treatment at 1273 K.

HiPco single-walled carbon nanotube (HPNT) containing Fe was purified by one-step purification with HCl-washing (D-method) and two-step purification with HCl-washing after air oxidation (GD-method)...

Poly(ɛ-caprolactone)diol (PCL)–functionalized nanodiamonds (f-NDs) were synthesized using a click chemistry reaction between the azide-moiety PCL and alkyne-moiety NDs and were incorporated into shape memory polyurethane (PU) at f-ND concentrations of 0, 0.5, 1, and 2 wt % to produce high-performance shape memory nanocomposites. The PU/f-ND nanocomposites exhibited better shape recovery, shape recovery stress, and breaking stresses than pure PU. Shape recovery of greater than 95% was demonstrated for all the nanocomposites in the third cycle, and the shape recovery stresses increased significantly with the f-ND content. These enhanced mechanical and shape recovery properties are ascribed to increased interactions between the f-NDs and PU matrix due to incorporation of click-coupled f-NDs. The click-coupled NDs can be used as nanofillers to enhance the mechanical and shape memory properties of polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45465.

Graphene synthesized via chemical vapor deposition is a notable candidate for flexible large-area transparent electrodes due to its great physical properties and its 2D activated surface area. Electrochromic devices in optical displays, smart windows, etc are suitable applications for graphene when used as a transparent conductive electrode. In this study, various-layer graphene was synthesized via chemical vapor deposition, and inorganic WO(x) was deposited on the layers, which have advantageous columnar structures and W(6+) and W(4+) oxidation states. The characteristics of graphene and WO(x) were verified using optical transmittance, Raman spectroscopy, x-ray photoelectron spectroscopy and scanning electron microscopy. The optimum transparent conductive electrode condition for controlling graphene layers was investigated based on the optical density and cyclic voltammetry. Electrochromic devices were fabricated using a three-layer graphene electrode, which had the best optical density. The graphene in the flexible electrochromic device demonstrated a potential for replacing ITO in flexible electronics.

N-alloyed activated carbon fibers (ACFs) were prepared by chemical vapor deposition (CVD) of pyridine on pitch-based ACF at 1023 K and 1273 K for 1 h. The N-alloyed ACFs were characterized by using the N2 adsorption at 77 K, CO2 adsorption at 273 K, elemental analysis, and X-ray photoelectron spectroscopy (XPS). The nitrogen content increases as a result of the pyridine-CVD. XPS examination showed that the percent of quaternary nitrogens in nitrogen structures increases remarkably from 60 to 91% for CVD temperatures of 1023 and 1273 K, respectively. The effects of N-alloying on adsorption properties of ACFs for C2H5OH and H2O were examined at 303 K. Both N-alloyed ACFs have a larger fractional filling of C2H5OH molecules. The uptake pressure of the H2O adsorption branches of both N-alloyed ACFs shifts to a lower relative pressure, compared with that of pristine ACF. Furthermore, the ratios of the VH2O (saturated amount of H2O at P/P0=1) to W0N2 (pore volume determined by N2 adsorption at 77 K) of N-alloyed ACFs are much larger than that of pristine ACF.

N-Alloyed activated carbon fibers (ACFs) were prepared by chemical vapor deposition (CVD) of pyridine on pitch-based ACF at 973−1273 K for 30−120 min. The N-alloyed ACFs were characterized by N2 adsorption at 77 K, elemental analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). The nitrogen content increases due to the pyridine CVD. XPS examination showed that the percent of quaternary nitrogens of total nitrogen atoms deposited increases remarkably up to 91% by the CVD at 1273 K, even though the surface concentration of nitrogen atoms was only 2.0%. The morphological development and surface chemistry of N-alloyed ACFs treated by pyridine CVD depended on the CVD temperatures. The CVD treatment decreased the surface area and pore volume, while the average micropore width was not significantly changed. The pyridine deposition at 1273 K for 60 min was the best preparation method of nitrogen-deposited ACF (ACF/Py1273-60) with high microporosity and positively charged surface nitr...