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The correlation between sorption capacity for heavy oil with a viscosity of 0.004 kg/m s and pore volume measured by a mercury porosimeter was studied on exfoliated graphite samples with different bulk densities. Pore volume measured by using the conventional dilatometer (N-type cell), which gives information on the pore size from 0.004 to 4 μm, was too low to explain the sorption capacity measured. However, pore volume measured by a special dilatometer (U-type cell) for large pore sizes up to 600 μm was very closed to sorption capacity. Pore volume measured by this U-type cell showed a linear relation to sorption capacity of exfoliated graphite samples, of which the slope was the same value as the density of heavy oil used (860 kg/m3). Therefore, large pores, which are reasonably assumed to be inter-particle pores among entangled worm-like particles of exfoliated graphite, were responsible for the large sorption capacity of heavy oils. Intra-particle pores inside and cleavage-like pores on the surface of worm-like particles were assumed to assist the capillary pumping of heavy oil. [Copyright &y& Elsevier]

Abstract: The formation of new acceptor-type graphite intercalation compounds (GICs) by traditional methods require a high oxidation potential, rendering the methods unsuitable for a number of compounds. Thus, we have synthesized novel acceptor-type GICs through an electrochemical method. Sodium dimethyldithiocarbamate (NaMDC) and sodium diethyldithiocarbamate (NaEDC) were selected as electrolytes for electrochemical processing in this study. Constant current electrolysis was applied for the synthesis of these acceptor-GICs. An exfoliated graphite sheet was used as the working electrode and a platinum plate in a three electrode cell was used as the counter electrode. Compounds synthesized in this way were identified using X-ray diffraction, enabling crystal structure determination. It appears that the intercalated graphite sheets exhibit a classical stacking in two layers such that there are regularly alternating electropositive and electronegative planes along the c-axis. It is shown that MDC and EDC–GICs were successfully synthesized through this electrochemical method. [Copyright &y& Elsevier]

Abstract Graphitic carbon nitride g -C 3 N 4 was reviewed on its structure, synthesis, texture control, modification and applications, associating with the comparative discussion to carbon materials. Its basic structural unit is a layer of either triazine or heptazine cores consisting of C and N atoms, similar with a layer of hexagonal carbon rings of most of carbon materials. Fundamental synthesis process of g -C 3 N 4 is pyrolysis of its precursors associated with different techniques, such as chemical vapor deposition, pressurizing, templating, doping, etc., as those applied for the synthesis of carbon materials. However, the properties of g -C 3 N 4 are quite different from those of carbon materials; the former is hydrophilic but the latter is hydrophobic, and the former is photoactive for visible light but the latter is non-active. Here, g -C 3 N 4 is reviewed on its structure, synthesis, texture control and modification, and application with comparative discussion to carbon materials. Graphical abstract Image [ABSTRACT FROM AUTHOR]

Abstract: An attempt was made to debundle single-walled carbon nanotube (SWCNT) bundle through intercalation techniques as in exfoliation of graphite. For this, SWCNT paper and lithium metal foil were simply short-circuited through electrolytes including lithium ions, and cathodic intercalation of lithium ions together with solvent molecules between the tubes that was expected to enlarge the spaces. It was found that the SWCNT paper could expand greatly through this technique using dimethyl sulfoxide electrolyte, and evidence of the intercalation reaction was confirmed by cyclic voltammetry. The paper after the debundling had some gaps between individual tubes in the bundles in the TEM picture, which were created through the present intercalation technique without any damage to the tubes themselves. [Copyright &y& Elsevier]

Exfoliation process of graphite via its residue compound from intercalation compound with sulfuric acid was discussed by measuring exfoliation volume and pore sizes among and inside their worm-like particles. Exfoliation process was found to divide into three steps, below 650, 650–800 °C and above 800 °C. Below 650 °C, exfoliation of graphite flakes to form worm-like particles occurred rapidly and so exfoliation volume increased. Above 650 °C, increase in exfoliation volume, i.e. decrease in bulk density, became more rapid, but the growth of pores inside the particles was not so much pronounced. Above 800 °C, the increasing rate in exfoliation volume seemed to become slow, change in bulk density looking small, but pores inside the particles grew more. Exfoliated graphite prepared at 1000 °C had the exfoliation volume of about 0.15 m3/kg (bulk density of about 7 kg/m3), which is composed of large spaces with the cross-sectional area of more than 8000 μm2 and worm-like particles containing ellipsoidal pores with averaged cross-sectional area of about 320 μm2 and sizes of about 31×11 μm2. [Copyright &y& Elsevier]

Exfoliated carbon fibers (ExCFs) of PAN- and pitch-based carbon fibers prepared by electrochemical processing followed by a rapid heat treatment have a large amount of edges because they have gone through the formation of graphite oxide and fragmentation. This is seldom observed in carbon nanotubes. This was clarified by the analysis of thermal programmed desorption and temperature programmed oxidation of the ExCFs. Carboxyl groups were generated at the edges by electrochemical processing. Subsequently the number of carboxyl groups decreased as a result of the rapid heat treatment, while the number of oxygen functional groups derived from CO increased. The differences in morphology of ExCFs prepared from PAN- and pitch-based carbon fibers seem to reflect the texture of the initial carbon fibers. [TANSO 2012 (No. 255), 245–253] [Copyright &y& Elsevier]

The intercalation mechanism for carbon fibers was discussed. Li-intercalation compounds of pitch-based carbon fibers (Li-ICCFs) were synthesized through electrical contact between lithium metal and carbon fibers in an electrolytic cell. Li-ICCFs containing both high- and low-stages were synthesized with all the carbon fibers used. It was also shown that high- and low-stage structures of Li-ICCFs coexisted during the intercalation process. The intercalation behavior of carbon fibers was discussed from the aspect of the crystallite size of the carbon fibers and the de-intercalation behavior of the Li-ICCFs obtained. It was found that the de-intercalation behavior of the carbon fiber differed from that of graphite such as graphitized sheets. It was shown that a different crystallinity in the internal texture of the carbon fiber is related to the intercalation behavior, making it different from graphite. [TANSO 2012 (No. 255), 237–244.] [Copyright &y& Elsevier]

Abstract: In this work, we have performed resonant photoemission studies of Ca-intercalated graphite superconductor CaC6. Using photon energy of the Ca threshold, the photoemission intensity of the peak at Fermi energy is resonantly enhanced. This result provides spectroscopic evidence for the existence of Ca states at , and strongly supports that Ca state plays a crucial role for the superconductivity of this material with relatively high . [ABSTRACT FROM AUTHOR]