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The quantum molecular sieving effects of pore-structure-controlled single-walled carbon nanotubes (SWCNTs) for H2 and D2 were evaluated at 20, 40, and 77 K. The adsorption amounts of D2 were larger than those of H2. The lower the adsorption temperature, the greater the difference between the D2 and H2 adsorption amounts. Bundled SWCNTs with interstitial pores of diameter 0.6 nm gave the greatest adsorption difference between D2 and H2 per unit pore volume. Diffusion-dominated behavior was observed in the low-pressure region at 20 and 40 K as a result of lower mobility. Bundled SWCNTs with only interstitial pores provided a significant quantum molecular sieving as a result of strongly interacting potential wells.

We demonstrate a water penetration mechanism through zero-dimensional nanogates of a single-walled carbon nanohorn. Water vapor adsorption via the nanogates is delayed in the initial adsorption stage but then proceeds at a certain rate. The mechanism is proposed to be a water cluster–chain–cluster transformation via the nanogates. The growth of water clusters in internal nanospaces facilitates water penetration into these nanospaces, providing an intrinsic mechanism for zero-dimensional water.

An air-stable Cu-carboxylate MOF complex can catalyze the cross-coupling reaction of phenylacetylene with 2-oxazolidone and Henry reaction. The Cu-carboxylate MOF encapsulated magnetic beads (MOF-MB II) was also prepared. The MOF-MB II was successfully reused in the Henry reaction by a simple magnetic separation.

We prepared a partially charged single walled carbon nanotube (SWCNT) by charge transfer-mediated encapsulation of methylene blue (MB) molecules, which enhances the CO2 adsorptivity. The liquid phase adsorption of MB molecules on SWCNT could give the MB-encapsulated SWCNT, which was evidenced by the remarkable depression of the X-ray diffraction intensity from the ordered bundle structure, the decrease of N2 and H2 adsorption in the internal tube spaces of SWCNT, and the high-resolution transmission electron microscopic observation. The molecular spectroscopic examination revealed the charge transfer interaction between the encapsulated MB molecules and SWCNT. The electrical conductivity increased by the encapsulation of MB suggested the electron transfer from SWCNT to MB molecules, giving rise to positively charged SWCNT. The enhancement of CO2 adsorption by the MB-encapsulation coincided with the positively charged SWCNT.

The gate adsorption mechanism and kinetics of an elastic layer-structured metal–organic framework (ELM), [Cu(bpy)2(BF4)2]n (ELM-11), that shows typical single-step CO2 gate adsorption/desorption isotherms accompanied with dynamic structural transformation in a wide temperature range were investigated. Adsorption of quite a small amount of CO2 on the external surface of ELM-11 crystals was observed at the pressure just below a gate adsorption pressure and induced a slight structural change in ELM-11. The structural change should start occurring at the outer parts of ELM-11 and transmit to more inner parts with rising pressure. The adsorption provides the stabilization of the framework through the interaction between fluid–solid and fluid–fluid and enables the framework to expand largely along the stacking direction. The CO2 adsorption rate of ELM-11 is almost comparable to that of Zeolite 5A at around ambient temperatures and shows temperature dependence with an anti-Arrhenius trend: higher adsorption rate...

A nanocrystalline composite of lithium nitride and lithium carbide was synthesized through melt infiltration of lithium metal into the mesopores of carbon aerogels followed by nitrogenation with nitrogen gas. The structure, surface properties, and morphology of the prepared samples were examined by XRD, N2 adsorption at 77 K, FE-SEM, FE-TEM, and TPD/MS. It was found that some of the lithium metal reacted with the carbon to form lithium carbide, and some of the lithium metal was transformed into lithium nitride by nitrogenation, yielding a composite of lithium nitride and lithium carbide. Relative to the bulk lithium nitride, the lithium nitride in the composite showed a significantly enhanced sequential hydrogen absorption capacity and a lowered temperature of hydrogenation/dehydrogenation.

Graphene and graphitic nanoribbons possess different types of carbon hybridizations exhibiting different chemical activity. In particular, the basal plane of the honeycomb lattice of nanoribbons consisting of sp(2)-hybridized carbon atoms is chemically inert. Interestingly, their bare edges could be more reactive as a result of the presence of extra unpaired electrons, and for multilayer graphene nanoribbons, the presence of terraces and ripples could introduce additional chemical activity. In this study, a remarkable irreversibility in adsorption of CO(2) and H(2)O on graphitic nanoribbons was observed at ambient temperature, which is distinctly different from the behavior of nanoporous carbon and carbon blacks. We also noted that N(2) molecules strongly interact with the basal planes at 77 K in comparison with edges. The irreversible adsorptions of both CO(2) and H(2)O are due to the large number of sp(3)-hybridized carbon atoms located at the edges. The observed irreversible adsorptivity of the edge surfaces of graphitic nanoribbons for CO(2) and H(2)O indicates a high potential in the fabrication of novel types of catalysts and highly selective gas sensors.

High-pressure adsorption isotherms of hydrogen onto amorphous carbon mesotubes (ACMs) prepared from fluorine polymer and onto activated carbon fibres (ACFs) were measured at temperatures of 77, 196 and 303 K, respectively, at pressures up to 10 MPa. The adsorption isotherms for ACMs and ACFs at 77 K exhibited maxima at 1 MPa (8.0 wt%) and 4 MPa (3.7 wt%), respectively, although both isotherms at 303 K were of the Henry type and both amounts of hydrogen adsorbed at 8 MPa were less than 0.3 wt%. The maximum hydrogen adsorption amount for ACMs per unit micropore volume as determined by N 2 adsorption was 10-times larger than that for ACFs. ACMs are different from ACFs in that they are thought to have specific ultramicropores, although characterization using high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy showed that they possessed a nanographitic structure similar to that of ACFs.

The adsorptivities of supercritical CH(4) and H(2) of the external and internal tube walls of single wall carbon nanotube (SWCNT) were determined. The internal tube wall of the negative curvature showed the higher adsorptivities for supercritical CH(4) and H(2) than the external tube wall of the positive curvature due to their interaction potential difference. Fine SWCNT bundles were prepared by the capillary force-aided drying treatment using toluene or methanol in order to produce the interstitial pore spaces having the strongest interaction potential for CH(4) or H(2); the bundled SWCNT showed the highest adsorptivity for supercritical CH(4) and H(2). It was clearly shown that these nanostructures of SWCNTs are crucial for supercritical gas adsorptivity., Article, ADSORPTION-JOURNAL OF THE INTERNATIONAL ADSORPTION SOCIETY. 17(3):643-651 (2011)

An outstanding compression function for materials preparation exhibited by nanospaces of single-walled carbon nanohorns (SWCNHs) was studied using the B1-to-B2 solid phase transition of KI crystals at 1.9 GPa. High-resolution transmission electron microscopy and synchrotron X-ray diffraction examinations provided evidence that KI nanocrystals doped in the nanotube spaces of SWCNHs at pressures below 0.1 MPa had the super-high-pressure B2 phase structure, which is induced at pressures above 1.9 GPa in bulk KI crystals. This finding of the supercompression function of the carbon nanotubular spaces can lead to the development of a new compression-free route to precious materials whose syntheses require the application of high pressure.

Selective synthetic routes to coordination polymers [Cu(bpy)(2)(OTf)(2)](n) (bpy = 4,4'-bipyridine, OTf = trifluoromethanesulfonate) with 2- and 3-dimensionalities of the frameworks were established by properly choosing each different solvent-solution system. They show a quite similar local coordination environment around the Cu(II) centers, but these assemble in a different way leading to the 2D and 3D building-up structures. Although the two kinds of porous coordination polymers (PCPs) both have flexible frameworks, the 2D shows more marked flexibility than the 3D, giving rise to different flexibility-associated gas adsorption behaviors. All adsorption isotherms for N(2), CO(2), and Ar on the 3D PCP are of type I, whereas the 2D PCP has stepwise gas adsorption isotherms, also for CH(4) and water, in addition to these gases. The 3D structure, having hydrophilic and hydrophobic pores, shows the size-selective and quadrupole-surface electrical field interaction dependent adsorption. Remarkably, the 2D structure can accommodate greater amounts of gas molecules than that corresponding to the inherent crystallographic void volume through framework structural changes. In alcohol adsorption isotherms, however, the 2D PCP changes its framework structure through the guest accommodation, leading to no stepwise adsorption isotherms. The structural diversity of the 2D PCP stems from the breathing phenomenon and expansion/shrinkage modulation.

The adsorption of cyclohexene with two sp2and four sp3carbon atoms in graphitic slit pores was studied by performing grand canonical Monte Carlo simulation. The molecular arrangement of the cyclohexene on the graphitic carbon wall depends on the pore width. The distribution peak of the sp2carbon is closer to the pore wall than that of the sp3carbon except for the pore width of 0.7 nm, even though the Lennard-Jones size of the sp2carbon is larger than that of the sp3carbon. Thus, the difference in the interactions of the sp2and sp3carbon atoms of cyclohexene with the carbon pore walls is clearly observed in this study. The preferential interaction of sp2carbon gives rise to a slight tilting of the cyclohexene molecule against the graphitic wall. This is suggestive of a π-π interaction between the sp2carbon in the cyclohexene molecule and graphitic carbon.

A two-dimensional flexible porous coordination polymer (2D-PCP) that shows expansion/shrinkage structural transformation accompanied by molecular accommodation was synthesized by control of dimensionality in zero-dimensional and one-dimensional PCPs: The dynamic structural transformation cooperatively proceeds in the solid state with a drastic molecular rearrangement. Kinetics of the structural transformation was investigated.

Coordination polymers (CPs) or metal-organic frameworks (MOFs) have attracted considerable attention because of the tunable diversity of structures and functions. A 4,4'-bipyridine molecule, which is a simple, linear, exobidentate, and rigid ligand molecule, can construct two-dimensional (2D) square grid type CPs. Only the 2D-CPs with appropriate metal cations and counter anions exhibit flexibility and adsorb gas with a gate mechanism and these 2D-CPs are called elastic layer-structured metal-organic frameworks (ELMs). Such a unique property can make it possible to overcome the dilemma of strong adsorption and easy desorption, which is one of the ideal properties for practical adsorbents.

Effect of pore width (w) and equilibration time on hysteresis of water adsorption isotherm was studied at 303–323 K using hydrophobic activated carbon fiber (ACF). The adsorption isotherm of ACF of w = 1.1 nm has a wide hysteresis loop; the longer the equilibration time from 5 min to 16 h, the narrower the loop width due to a lower pressure shift of the adsorption branch. This fact indicates that adsorption branch stems from a metastable adsorption.

Activated carbon fibres with extremely high surface areas (ACFs) were prepared by CO2 re-activation using pitch-based ACFs having an original surface area of 1730 m2/g. The highest surface area of the re-activated ACFs was 2930 m2/g as determined from an αS-plot analysis of the nitrogen adsorption isotherm measured at 77 K. The ACF with the highest surface area showed excellent adsorptivity towards supercritical CH4 and H2. The amounts of CH4 and H2 adsorbed were enhanced by 52% and 30%, respectively, as a result of re-activation.

A new catalyst for efficient production of H 2 from CH 4 without CO 2 emission has been requested. We prepared highly-dispersed Pd nanoparticles on single wall carbon nanohorn (Pd-SWCNH) and on oxidized SWCNH (Pd-oxSWCNH) without an anti-aggregation agent. The Pd nanoparticle size on SWCNH and oxSWCNH determined by electron microscopy are around 2.5 and 2.7 nm, respectively. Each sample provides efficiently H 2 and hollow carbon nanofibers through CH 4 decomposition. The H 2 release over the Pd-dispersed SWCNH samples starts from ca. 820 K and is quite large amount compared with a commercial Pd-activated carbon.

Single-wall carbon nanotube (SWCNT) bundles were pillared by fullerene (C60) by the cosonication of C60 and SWCNT in toluene to utilize the interstitial pores for hydrogen storage. C60-pillared SWCNTs were confirmed by the shift in the X-ray diffraction peak and the expanded hexagonal and distorted tetragonal bundles revealed by high-resolution transmission electron microscopy. The H2 adsorptivity of the C60-pillared SWCNT bundles was twice that of the original SWCNT bundles, indicating a design route for SWCNT hydrogen storage.

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.

We have investigated the applicability of simulations and theoretical techniques for exploring the selectivities of hydrogen isotopes. We have simulated the adsorption isotherms of H2 in an idealized carbon slit pore at 77 K by using the grand canonical Monte Carlo simulations with the Feynman-Hibbs effective potential (FH-GCMC) and the rigorous path integral method (PI-GCMC), and we obtained good agreement between the isotherms from both simulations. This suggests that FH-GCMC, which uses the approximative Feynman-Hibbs treatment, is as useful as PI-GCMC for exploring H2 adsorption at 77 K. Moreover, we show that the ideal adsorption solution theory (IAST) can predict the selectivity of D2 over H2 in the interstices of single-wall carbon nanotube (SWNT) bundles at 77 K (below 0.1 MPa) very well by comparing the obtained results with the mixture adsorption FH-GCMC simulations. This indicates that IAST is also applicable to the estimation of the selectivity of D2 over H2 at moderate pressures and at 77 K from experimental single-component adsorption isotherms. We also demonstrate that the FH-GCMC simulation can reproduce the experimental adsorption isotherms of H2 and D2 in aluminophosphate AlPO4-5 at 77 K. Finally, we analyze the selectivity of D2 over H2 by IAST with the experimental single-component adsorption isotherms of H2 and D2 at 77 K for a variety of adsorbents: AlPO4-5, activated carbon fibers (ACFs), HiPco SWNT, and SWNHs. The selectivities predicted by the experimental adsorption data based on the results from the FH-GCMC simulations are presented and discussed.

Elastic layer-structured metal organic frameworks (ELMs) having flexible two-dimensional structure show a gate phenomenon in sorption/desorption of simple gas molecules. The gate phenomenon is accompanied by expansion/shrinkage of the layers. The gas sorption/desorption is not based on a physical adsorption, but on a chemical reaction, which includes high cooperativity. The cooperative reaction could be analyzed thermodynamically. The gate phenomenon showed advantages in separation of CO2 from mixed gases and in storage of CH4 owing to easy release of absorbed molecules.

N2 adsorption isotherms of molecular sieve carbon were measured at 77 K and 303 K. The Ar adsorption isotherms of molecular sieve carbon samples were also measured at 303 K. The grand canonical Monte Carlo (GCMC) simulation technique was applied to calculate the N2 and Ar adsorption isotherms at 303 K using the ultramicropore volume determined by H2O adsorption. The comparative method of experimental and simulated isotherms of supercritical N2 and Ar at 303 K gave the width of the micropore mouth of the molecular sieve carbon, which can be applied to the ultramicropore width determination for other noncrystalline porous solids.

It is important to study the interaction between water molecules and a host structure for understanding the adsorption mechanism of metal-organic framework (MOF) materials. The evolution of the structure of a flexible Cu-MOF, {[Cu(bpy)(H2O)2(BF4)2](bpy)} (bpy=4,4'-bipyridine), upon dehydration and rehydration was studied by thermogravimetric analysis (TGA), infrared (IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and water adsorption. A nearly reversible structural change was observed upon rehydration. More importantly, a unique CO2 "gate adsorption" phenomenon was observed despite the exposure of the Cu-MOF to water. This shows that the Cu-MOF has relatively good stability after exposure to water.

Nanoporous composites of carbon nanosheets and single or mixed TiO2 and SiO2 were synthesized from graphite oxide (GO) precursor by a mechanochemical intercalation (MCI) method and their structural and adsorption/photocatalytic properties examined. It was found that a mixed Ti and Si organic phase behaves differently from a single phase in the MCI process, with linkages of SiO2 and TiO2 forming between the carbon layers, leading to an intercalation structure with improved surface hydrophilicity and a composite with enhanced microporosity and a reduced total amount of oxides. Although structural regularity of intercalated GO becomes poorer by applying Ti species in the MCI method, carbon-mixed oxide composites with an appropriate pore structure and sufficient Ti content exhibit a synergy effect of adsorption concentration and photocatalysis toward organic molecules.

I2 was adsorbed on single-walled carbon nanotube from ethanol solution at 303 K. The I2 adsorption isotherm was Langmuirian, giving 35 (+/-10) mg g(-1) of the saturated adsorption amount (coverage 0.06-0.09). The I2-adsorption treatment of SWCNT bundles reduced the N2 adsorption amount at 77 K by only 3%; the adsorption amount of supercritical H2 at 77 K was decreased by 30% because of the I2-adsorption treatment, indicating the blocking of interstitial pores by adsorbed I2. These adsorption results indicated the adsorption of I2 molecules in the narrow interstitial pores. The I2-adsorption treatment increases the Raman intensity coming from metallic SWCNTs, and the dc electrical conductivity increased by 15% because of the I2-adsorption treatment, strongly suggesting the presence of charge-transfer interaction between I2 and SWCNTs irrespective of small coverage by I2.

The nanoporosities and catalytic activities of Pd nanoparticles dispersed on single wall carbon nanohorns (Pd-SWCNHs) and oxidized single wall carbon nanohorns (Pd-ox-SWCNHs) were examined. A transmission electron microscopy (TEM) observation indicated that Pd nanoparticles of 2–3 nm size were highly dispersed on both the SWCNHs. X-ray photoelectron spectra and N2 adsorption isotherms at 77 K illustrated the differences in the deposition process mechanisms of the Pd-SWCNHs and Pd-ox-SWCNHs; the deposition process depended on the surface functional groups. The supercritical H2 adsorption isotherms at 77 K suggested the relationships between the interaction of Pd-SWCNHs and Pd-ox-SWCNHs with H2 and the catalytic activities for a water formation reaction in a gas phase at 273 or 298 K. The catalytic activity measurement and TEM observation of the catalysts after the reactions demonstrated that the Pd-SWCNHs and Pd-ox-SWCNHs are promising catalysts.

Titanium dioxide nanocrystalline particles were synthesized by peroxo titanium acid (PTA) approach from titanium alkoxide and inorganic salt precursors, and their structural and surface properties, porosities, and photocatalytic activities were comparatively examined by XRD, TG/DTA, DRIFT, UV-vis, low temperature N(2) adsorption, and methyl orange (MO) degradation. It was found that nanoparticles with single anatase phase can be obtained from alkoxide precursor even near room temperature if synthesis conditions are appropriately controlled. PTA-derived anatase nanoparticles from titanium alkoxide precursor have smaller crystalline sizes and better porosities, and contain less amount of peroxo group and no organic impurities as compared to those from TiCl(4) precursor. The advantages in structural property, porosity, and surface properties (few deficiencies) lead to a much better photocatalytic activity for TiO(2) nanoparticles from titanium alkoxide precursor in comparison with those from TiCl(4) precursor.

Single-wall carbon nanohorns (SWCNHs) and partially oxidized SWCNHs (ox-SWCNHs) were mechanochemically treated for the elucidation of their unique chemical bonding state. The mechanochemical treatment promoted the transformation from sp2 to sp3 bonding from XPS, leading to an increase and decrease in the micropore volume for SWCNHs and ox-SWCNHs, respectively. The changes in the micropore volume and the electrical conductivity responses on CO2 adsorption indicate the occurrence of tubulite-to-tubulite reconstruction in SWCNH through unstable sp3 bonding.

The crystal structure of [Cu(4,4'-bipyridine) 2(CF 3SO 3) 2] n metal-organic framework (CuBOTf) of one-dimensional pore networks after pre-evacuation at 383 K was determined with synchrotron X-ray powder diffraction measurement. Effective nanoporosity of the pre-evacuated CuBOTf was determined with N 2 adsorption at 77 K. The experimental H 2 and D 2 adsorption isotherms of CuBOTf at 40 and 77 K were measured and then compared with GCMC-simulated isotherms using the effective nanoporosity. The quantum-simulated H 2 and D 2 isotherms at 77 K using the Feynman-Hibbs effective potential coincided with the experimental ones, giving a direct evidence on the quantum molecular sieving effect for adsorption of H 2 and D 2 on CuBOTf. However, the selectivity for the 1:1 mixed gas of H 2 and D 2 was 1.2. On the contrary, experimental H 2 and D 2 isotherms at 40 K had an explicit adsorption hysteresis, originating from the marked pore blocking effect on measuring the adsorption branch. The blocking effect for quantum H 2 is more prominent than that for quantum D 2; the selectivity for D 2 over H 2 at 40 K was in the range of 2.6 to 5.8. The possibility of the quantum molecular sieving effect for H 2 and D 2 adsorption on [Cu 3(benzene-1,3,5-tricarboxylate) 2(H 2O) 3] n of three-dimensional pore networks was also shown at 77 K.

Surface-enhanced Raman scattering (SERS) was applied to investigate the fine nanostructure of single-wall carbon nanohorns (SWCNHs) and partially oxidized SWCNHs of which Raman D bands are predominant. SERS of SWCNH samples was measured in vacuo by deposition of SWCNH particles on silver foil with evaporation of SWCNHs-dispersed solvent. New peaks were observed over the wavenumber range of 200 to 1700 cm−1 in addition to peaks observed in normal Raman scattering. The new SERS peaks are tentatively assigned to the vibrational mode due to topological defects such as the pentagon and heptagon.

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.

The experimental adsorption isotherm of N2 molecules on mutually isolated single wall carbon nanotubes at 77 K agreed well with the grand canonical Monte Carlo simulated one. The N2 adsorption isotherm had two steps stemming from monolayer formation on the internal surface and filling of the residual space of the internal tube pore. Although all of radial distribution functions of molecules adsorbed on the internal, external, and flat surfaces indicated a hexagonal packing structure, the radial distribution functions were different from each other. In particular, the radial distribution function of the monolayer on the internal surface showed an additional peak because of the markedly curved surface.

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.

We showed water adsorption isotherms at 303 K on water-resistant three-dimensional (3-D) pillared-layer metal organic frameworks (MOFs) with 1-D semi-rectangular pores, of which size depends on the length of ligand. The shapes of all three adsorption isotherms are type I by IUPAC classification showing strong water-MOFs interaction. The adsorbed amount of water molecules on the hydrophilic site of carboxylic group in 2-D sheets coincided with the crystal water amount. The adsorption on the hydrophilic sites occurs at similar relative pressure even if the used ligand is different.

Interfacial importance and nanopore structures of single wall nanocarbons such as single wall carbon nanotube (SWCNT) and single wall carbon nanohorn (SWCNH) are described in terms of intermolecular interaction theory. The relationships between the nanopore structure and nanoconfinement effect for molecules and ions are shown using examples on supercritical H2 adsorption on SWCNT, quantum molecular sieving effect of SWCNT for H2 and D2 below 77 K, water structure and hydration structure of Rb, Cs, and Sr ions in nanopores of activated carbon fiber and SWCNH, and capacitance storage of SWCNH. The SWCNT produced by laser ablation shows upward-curved adsorption isotherm of H2 at 77 K, suggesting the presence of the strong sites. The adsorption amount of D2 on this SWCNT at 77 K was clearly larger than that of H2 by about 20% at 77 K due to quantum effect. The hydration number around Cs and Sr ions in 1.1 nm slit pores of ACF reduced by more than 20 %. The capacitance depended on the opening of SWCNH and charging time for organic electrolyte (C2H5)4NBF4 in propyrene carbonate.

The temperature and magnetic field dependences of magnetic characteristics of an organic radical (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL)) adsorbed on oxidized single-wall carbon nanohorn (ox-NH) were studied with a SQUID magnetometer and an electron spin resonance (ESR) spectrometer. TEMPOL molecules adsorbed on ox-NH do not form any ordered structures, but the formation of disordered clusters was suggested because of intensive restriction by nanoconfinement. Exchange interaction of TEMPOL adsorbed on ox-NH was weaker than that of bulk TEMPOL. Slow relaxation phenomena of magnetization and paramagnetic behaviors were observed by confinement of TEMPOL in nanospace.

Fluorinated activated carbon fibers (F-ACFs) were prepared by direct thermal fluorination of pristine activated carbon fibers. By the pyrolysis of F-ACFs at 1073 K under nitrogen gas flow, fluorine was subsequently eliminated and the sp2-bonded ACF structures were recovered. The micropore widths were 1.1 and 0.8 nm, and the isosteric heats of adsorption of nitrogen were 11.3 and 12.8 kJ/mol for pristine and defluorinated ACFs, respectively. These results strongly suggest that changes occurred in the structural properties of micropores in defluorinated ACFs. The hydrogen adsorption isotherms showed that the defluorinated ACFs adsorbed more hydrogen gas than pristine ACFs at 77 K, suggesting that the potential for interaction between hydrogen molecules and the defluorinated slit nanospaces was increased due to the changes in the pore structural properties and/or to the induced polarization of the pore walls making up the modified π-electron systems.

Naphthalene was adsorbed on single wall carbon nanotubes (SWNT) from trichloroethylene solution. The adsorbed state of naphthalene on dry SWNT samples was studied with X-ray photoelectron spectroscopy and Raman spectroscopy. Adsorption of naphthalene molecules on SWNTs in trichloroethylene provide a uniform coating of external surface of individual SWNTs. Also, a technique of the liquid phase adsorption of naphthalene succeeded to control the assembly structure of the SWNTs, leading to an explicit adsorption hysteresis in the nitrogen adsorption isotherm at 77 K.

The dispersion process of single-wall carbon nanotube (SWNT) by using sodium dodecylbenzene sulfonate (NaDDBS) was studied by means of surface tension measurements, ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and transmission electron spectroscopy (TEM). The critical micelle concentration (CMC) and the concentration where the surface tension begins to drop increase by the presence of SWNT. The isotherm of NaDDBS amount adsorbed on SWNT shows the plateau region at 0.2-6 mM and the saturated region above 40 mM. The external surface of SWNT bundle is fully covered with adsorbed NaDDBS at the plateau region, showing that SWNTs can be dispersed with the bundle form. On the other hand, SWNTs are dispersed in individual tubes at the saturated region, where the adsorption amount corresponds to coating of individual tube surfaces with NaDDBS. This dispersion state was confirmed by SEM and TEM observations. The effect of the dispersion state of SWNTs on radial breathing mode in Raman spectrum gave inherent peak shifts, being the in situ evidences on the step-wise dispersion mechanism of the SWNT bundle to the individual tubes.

The structure of single-wall carbon nanohorn (SWNH) was analyzed with X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The considerably strong peak due to single bonding carbons was observed in C1s XPS spectrum of SWNH. This peak intensity increases with oxidation treatment, coinciding with the decrease in Raman G/D intensity ratio. It is concluded that the presence of a considerable amount of single bonding carbons is the reason for the unique assembly structure accompanying with a strong D-band in Raman spectrum of SWNH.

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.

Novel nanostructured carbon material was synthesized by applying zeolite LTA as a template and using methanol as a carbon source. X-ray diffraction (XRD) revealed that the higher the decomposition ...

Graphene has become a primary material in nanotechnology and has a wide range of potential applications in electronics. Fabricated graphenes are generally nanosized and composed of stacked graphene layers. The edges of nanographenes predominantly influence the chemical and physical properties because nanographene layers have a large number of edges. We demonstrated the edge effects of nanographenes and discrimination against basal planes in molecular adsorption using grand canonical Monte Carlo simulations. The edge sites of nanographene layers have relatively strong Coulombic interactions as a result of the partial charges at the edges, but the basal planes rarely have Coulombic interactions. CO2 and N2 prefer to be adsorbed on the edge sites and basal planes, respectively. As a result of these different preferences, the separation ability of CO2 is higher than that of N2 in the low-pressure region, thereby offering selective adsorptions, reactions, and separations on nanographene edges.

SF6 and SF6-N2 mixed gases are used widely as insulators, but such gases have high greenhouse gas potential. The separation of SF6 from SF6-N2 mixed gases is an inevitable result of their use. Single-walled carbon nanohorns (CNHs) were used here for a fundamental study of the separation of SF6 and N2. The diameters of the interstitial and internal nanopores of the CNHs were 0.7 and 2.9 nm, respectively. The high selectivity of SF6 over N2 was observed only in the low-pressure regime in the interstitial 0.7 nm nanopores; the selectively was significantly decreased at higher pressures. In contrast, the high selectivity was maintained over the entire pressure range in the internal 2.9-nm nanopores. These results showed that the wide carbon nanopores were efficient for the separation of SF6 from the mixed gas.