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Carbonization and post-activation of polysaccharides (utilized as food residue) created new bio-nanocarbons for the electrode of electric double layer capacitors (EDLC). Large specific capacitance (46.1 F/g, 26.4 F/cm 3 ) and high rate performance was confirmed under optimized conditions of carbonization temperature (600 °C) and supplied amount of sodium hydroxide in NaOH-activation process (250 wt %). The capacitance and rate performance were larger than the reported values, 42.9 F/g, 19.7 F/cm 3 of currently used activated carbon MSP-20. The feature that NaOH is usable as the activation agent, instead of KOH, is advantageous for reducing the cost of EDLC. [ABSTRACT FROM AUTHOR]

Carbonization and post activation of bamboo-cellulose fiber was carried out. The carbonization was performed at 600 °C, 800 °C and 1000 °C in argon atmosphere. Then, they were activated by heating solid mixture of carbonized bamboo and sodium hydroxide (NaOH) at 720 °C in argon atmosphere. The largest specific surface area of the resulting activated carbon (carbonized at 600 °C) was 2366 m 2 /g with the micropore volume of 0.71 cm 3 /g and mesopore volume of 0.06 cm 3 /g. It was found that the carbonization temperature is very important to obtain nanoporous carbon with large specific surface area. The distributions of interlayer spacing were estimated from the power spectra of the TEM images of the carbonized samples. It showed the interlayer spacing of basic structural unit (BSU) decreased from 0.49 nm (BC-0600) through 0.47 nm (BC-0800) to 0.45 nm (BC-1000). The activated carbon was used as the host material of the electrodes of coin type electric double-layer capacitor (EDLC) with organic electrolyte. The observed specific capacitance was 43 F/g (23 F/cm 3 ) for the activated carbon (carbonized at 600 °C), comparable to 44 F/g (22 F/cm 3 ) of commercial activated carbon (MSP). The corresponding values for the activated carbons (carbonized at 800 °C and 1000 °C) were 40 F/g (23 F/cm 3 ) and 17 F/g (12 F/cm 3 ), respectively. [ABSTRACT FROM AUTHOR]

This paper reports on the contact resistance ( R c ) between carbon filler/natural rubber (NR) nanocomposite and gold ball: three varieties of nanocomposites were prepared from carbon black (CB) and two kinds of multi-walled carbon nanotubes (MWCNTs) with different diameter. R c of MWCNT/NR nanocomposite was remarkably less than that of CB/NR nanocomposites. The relationship between R c of MWCNT/NR nanocomposites and applied load was expressed in the formula, R c = C · P − n ( P : load, C and n : constant): for the MWCNTs (diameters of 13 nm)/NR and MWCNTs (diameters of 67 nm)/ NR nanocomposites, they were expressed as R c =1724· P −0.6 and R c =344· P −0.37 , respectively. The former (MWCNT, ϕ 13 nm) showed higher R c than the latter (MWCNT, ϕ 67 nm) over whole region of applied load. The mechanical hardness of the former was higher (90 HsA) than that of the latter (82 HsA). Therefore, the smaller contact area between the nanocomposite and gold ball of the former resulted in higher R c . The apparent specific contact resistivity was calculated from the observed values of R c and contact area: 130 Ω mm 2 and 127 Ω mm 2 for the former (MWCNT, ϕ 13 nm) and the latter (MWCNT, ϕ 67 nm), respectively. [ABSTRACT FROM AUTHOR]

We prepared a polysulfone (PSU) support by applying a coating of a PSU-N,N-dimethylformamide (DMF) solution on 91 µm thick nonwoven and then set it in water (the phase inversion process). The prepared PSU-substrate sheet was 280 mm wide and 10 m long. We then investigated the effects of the preparation conditions (i.e., the concentration of the PSU-DMF solution and the coating thickness) on the water permeability of the resulting PSU support. The thickness of the PSU layer increased almost linearly with the increase in the coating thickness, and the water permeability decreased monotonically with the increase in the PSU layer's thickness. A bubble point analysis revealed that the pore size dia. of the membranes was approx. 20–60 nm, depending on the PSU-DMF solution's concentration. Using these PSU membranes as the support, we prepared a reverse-osmosis (RO) membrane, the active layer of which consisted of aromatic polyamide (PA) that contained carbon nanotubes. The salt rejection rate 99.7% and water permeability at 0.56 L m−2 h−1 bar−1 were achieved at 5.5 MPa for a 3.2% NaCl solution with the RO membrane, the support of which was prepared from a 17.0% PSU-DMF solution. [Display omitted] • Investigated the effect of the PSU concentration in a PSU-DMF solution. • The effect of the coating thickness on the water permeability. • The salt rejection rate 99.7% was achieved at 17.0% PSU-DMF solution. [ABSTRACT FROM AUTHOR]

Abstract: High-speed agitation by a mixing blade has efficiently achieved the cutting of a large diameter (100–150nm) of multi-walled carbon nanotubes. The cutting process is caused by an inter-collision of the nanotubes with high transfer energy. The collision-induced cutting allows for the shortening of the nanotubes without serious damage of the original graphitic layers due to the cutting effect being limited to the collision points. Furthermore, the operation under ambient atmosphere introduces oxygen-containing functional groups to the cut nanotubes. The estimated length distribution has indicated that high-speed agitation achieves a large cutting effect during a short duration of several minutes. [Copyright &y& Elsevier]

Abstract A one-dimensional (1D) graphene fiber with a novel structure has been prepared by a heat treatment of rice husk, a natural by-product that contains high amounts of silica. A step-by-step heat treatment of rice husk revealed that (i) carbonization yields porous carbon and silica, (ii) 1D β -SiC nanowires are formed by the carbothermic reduction of silica, (iii) finally 1D graphene fibers are created by silicon sublimation from 1D β -SiC nanowires. Raman spectroscopy and electron microscopy studies revealed that the graphene fiber is composed of a turbostratic multilayer structure. The SiC-derived material exhibits a large crystalline size and turbostratic stacking making each layer as quasi-free-standing graphene, which is confirmed by the 3.9 times higher Raman G′-band intensity over the G-band intensity. Molecular dynamics simulations revealed a high diffusion rate of Si atoms and a volume reduction of the SiC structure at the sublimation temperature. Since the silicon sublimation occurred from multiple points of the SiC nanowire, this led to radially-collapsed fibers and faceted structures with thick-graphitic-layer that are inter-connected (deflated-balloons and inter-connected balloon-like fibers). This facile synthesis route opens up a new avenue to the cost-effective and etching-free production of self-standing graphene for its bulk usage. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Graphitization of carbon materials plays an important role their microstructures and conductivity, and then influences their applications. However, the graphitization of hydrothermal carbon spheres (CSs) has not systemically investigated heretofore. The CSs with 60–250 nm in diameter were prepared from aqueous glucose solution by hydrothermal carbonization, and were treated at the high temperatures of 900–2900 °C in Ar atmosphere. The heat-treated CSs have demonstrated that their surface structure, microstructure, porosity, and polygonization strongly depend on the treatment temperatures. These results are supported by scanning and transmission electron microscopes, energy dispersive x-ray spectrometry, Raman, X-ray diffraction, and BET surface area analyses. We also investigated the electrical properties of the heat-treated CSs under compression, and found that the resistivity of the carbon particles is very dependent on their surface, microstructure, density, and polygonization. Therefore, high temperature treatment is an effective method to tailor the structure, morphology, and property of the hydrothermal CSs. [ABSTRACT FROM AUTHOR]

Recently, graphene and carbon nanotube (CNT) composites have attracted great interest of scientists and exhibited fascinating properties even better than they could on their own. Here, we have synthesized the graphenated CNTs (g-CNTs), one of graphene–CNT composites, from waste rice husk (RH) by one-step microwave plasma irradiation (MPI) process. The RH-derived g-CNTs were composed of graphene standing on the sidewalls of CNTs, in which the graphene sheets possessed a large amount of sharp edges, which mainly consisted of 2–6 layers, and the CNTs had several tens of micrometers in length and 50–200 in diameter. They offer great promise in the application of electrochemical electrodes due to their special features including high surface area and specific capacitance. The successful MPI technique can be spread to other waste biomass, in which their components are made of cellulose, hemicellulose, and lignin similar to RHs, to fabricate high-added-value nanocarbons including graphene, CNTs, and g-CNTs, which were dependent of experimental pressure. [ABSTRACT FROM AUTHOR]

Helical graphite whiskers (GWs) have been synthesized from fullerene waste soot, which is a byproduct in fullerene production by arc discharge technique, at 2600 °C for 1 h with Ar gas flow at 760 Torr. The as-synthesized GWs consisting of graphite layers with some disclination possess various kinds of morphological structures with loop-like brims and arch-shaped protrusion on their surfaces, as observed by scanning and transmission electron microscopy. The GWs show strong intensity of 2D peak in Raman spectra, which could be attributed to disclination in the whiskers. [ABSTRACT FROM AUTHOR]

We aim to develop high-level applications of NR through the innovative use of multi-walled carbon nanotubes (MWCNTs) to improve reinforcing performance and thermal resistance. In this study, we examined the structures and characteristics of composite materials in which NR was the matrix and MWCNTs were the fillers. We studied the properties of composites containing surface-activated MWCNTs with three different diameters. The results show that the reinforcing performance improves as MWCNT diameter decreases, while thermal resistance improves as we decrease the heat-treatment temperature. The latter occurs because adherence between MWCNTs and NR becomes stronger at lower heat-treatment temperatures. We also found that for practical applications, we need to control active sites on MWCNTs to balance adhesion against thermal resistance. [ABSTRACT FROM AUTHOR]

Abstract: Vertically-aligned carbon nanosheets (CNSs) have been fabricated on the Cu substrate from Kapton polyimide (PI) film under Ar/H2 plasma irradiation. The high purity CNSs possess petal-like structures with many sharp edges, which are composed of few-layer graphene sheets. In addition, the irradiated Kapton PI film was covered by a layer of urchin-like carbon particles with about 4μm in diameter, which also consist of few-layer graphene sheets along radial directions. Except for the morphologies, both the CNSs and urchin-like carbon particles demonstrate similar microstructures and chemical compositions. [Copyright &y& Elsevier]

Vertically-aligned carbon nanosheets (CNSs), which were fabricated by microwave plasma-enhanced chemical vapor deposition in Ar and CH4 system, have been annealed at high temperatures in the range of 1200–3000°C. The morphologies and microstructures of the treated CNSs were analyzed by scanning and transmission electron microscopes, and Raman spectroscopy. High temperature treatment process efficiently removed the amorphous carbon and some defects and improved the graphitization of the CNSs. The graphitized grains increase and the interlayer spacing decreases with increasing heat temperatures. Heat treatment of the CNSs at temperatures from 1500 to 2000°C was found to achieve the edges consisting of many single-layer graphene sheets. Annealing at temperatures above 2100°C, the edges of nanosheets consist of 2–5 layer graphene with many zigzag junctions. The mechanism of reconstruction for the edges in the CNSs ascribes possibly to the carbon atom vaporization at high temperatures. [ABSTRACT FROM AUTHOR]

Magnetoresistance and Hall coefficient of air-stable potassium-intercalated graphite sheets (hereafter abbreviated as K-PGS) were determined at room temperature. The magnitude of the magnetoresistance and the absolute value of Hall coefficient of K-PGS decreased with increasing potassium content of K-PGS, n K/n C. Two-carrier model was used for calculating carrier density and mobility. The electron density increased with increasing n K/n C: 3.07×1020 cm−3 (n K/n C=0.005), 5.67×1020 cm−3 (n K/n C=0.008) and 6.40×1020 cm−3 (n K/n C=0.011). The value of the electron density of K-PGS with n K/n C=0.011 (nominal composition KC91) was about 80% of the reported value, 7.8×1020 cm−3, for KC48 (n K/n C=0.021) prepared from HOPG (highly oriented pyrolytic graphite). The mobility decreased with increasing n K/n C: 2.11×103 cm2 V−1 s−1 (n K/n C=0.005), 1.42×103 cm2 V−1 s−1 (n K/n C=0.008) and 1.34×103 cm2 V−1 s−1 (n K/n C=0.011). The value of the mobility of K-PGS with n K/n C=0.011 was about 60% of the reported value (2300cm2 V−1 s−1) for KC48 prepared from HOPG. [ABSTRACT FROM AUTHOR]

Potassium–graphite intercalation compounds with chemical compositions of KC84, KC48, KC36 and KC8 were prepared from PGS graphite sheet and then treated with 6M-HCl aqueous solution. After washing with water and drying under open air, chemical composition, stage structure and electrical conductivity of the resulting air-stable compounds were determined. It was found that about 40% of potassium in the starting potassium–graphite intercalation compounds remained in the matrix after treated with 6M-HCl aqueous solution for KC84, KC48 and KC36, while 15% for KC8. The room temperature electrical conductivity of an air-stable compound, containing potassium of 0.008 in molar ratio of potassium to carbon, was determined to be 1.3×105 Scm−1. This is comparable to that of iron (1.0×105 Scm−1) and about 1/3 of that of aluminum (3.6×105 Scm−1). [ABSTRACT FROM AUTHOR]

Abstract: The quantitatively limited use of hydrogen peroxide in supercritical water allows for the in situ formation of iron oxides and graphitic carbon from ferrocene in one step. The structure of the particles prepared at 400–500°C is comprised of nano- to micro-meter size of magnetite and maghemite cores covered with graphitic carbon shells. The morphology and size of the core–shell particles and the phase composition of iron-oxide cores are different dependent on the preparation conditions. The particles prepared at 400°C contain, as dominant iron-oxide phase, the magnetite core particles ranging from nano- to micro-meter scales with no morphological regularity, while those prepared at 500°C are comprised of hexagram shape and micro-meter size of maghemite cores. The observed morphology, the dimension of the core particles, and the dominant phase composition suggested that the iron-oxide cores would be formed through the oxidation of iron(II) to iron(III) and two different hydrolysis paths. Furthermore, the higher preparation temperature of 500°C has shown a tendency to form smaller crystallite sizes of polycrystalline iron-oxide cores. The decrease of subcrystal sizes in the vicinity of superparamagnetic thresholds effects the reduction of coercivity in the ferromagnetic hysteresis. [Copyright &y& Elsevier]