大場 友則

The preparation of nitrogen-rich activated carbon can be achieved by the use of nitrogen-rich precursor or by the nitrogenous modification for carbon surface. In this study, the activated carbon fiber (ACF) was prepared from polyacrylonitrile (PAN) containing ca. 25 wt% nitrogen as a precursor. The prepared PAN-ACF was further treated by urea as a nitrogen medium to introduce the nitrogen functional groups after air oxidation treatment. The surface analysis of urea-treated PAN-ACF by X-ray photoelectron spectroscopy (XPS) revealed that the amount of negatively charged nitrogen species was relatively high compared to PAN-ACF. The result of Cd(II) adsorption experiment indicated that the amount of Cd(II) adsorption was increased in the order of commercial ACFs, PAN-ACF and urea-treated PAN-ACF. The examination of the effect of coexistence between Cd(II) and aromatic compound indicated that Cd(II) adsorbed on p electron clouds of the nitrogen-poor ACF, while not only p electron clouds but also newly introduced specific basic nitrogen/oxygen functional groups contributed to Cd(II) adsorption. These specific sites would not be affected by aromatic compounds.

Superuniform nanosized gates (nanogates; 0.41 +/- 0.02 nm in size) were donated on graphene sheets of single wall carbon nanohorn (SWCNH) particles by controlled oxidation. Superuniform nanogate donation confers high molecular selectivity and large adsorption capacity upon SWCNH. The molecular selectivity of CO2 over CH4 attains 17 below 0.01 MPa by the nanogate separation.

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, N-2 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. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

We synthesized two high-pressure polymorphs PbNiO3 with different structures, a perovskite-type and a LiNbO3-type structure, and investigated their formation behavior, detailed structure, structural transformation, thermal stability, valence state of cations, and magnetic and electronic properties. A perovskite-type PbNiO3 synthesized at 800 degrees C under a pressure of 3 GPa crystallizes as an orthorhombic GdFeO3-type structure with a space group Pnma. The reaction under high pressure was monitored by an in situ energy dispersive X-ray diffraction experiment, which revealed that a perovskit-type phase was formed even at 400 degrees C under 3 GPa. The obtained perovskite-type phase irreversibly transforms to a LiNbO3-type phase with an acentric space group R3c by heat treatment at ambient pressure. The Rietveld structural refinement using synchrotron X-ray diffraction data and the XPS measurement for both the perovskite- and the LiNbO3-tyze phases reveal that both phases possess the valence state of Pb4+Ni2+O3. Perovskite-type PbNiO3 is the first example of the Pb4+M2+O3 series, and the first example of the perovskite containing a tetravalent A-site cation without lone pair electrons. The magnetic susceptibility measurement shows that the perovskite- and LiNbO3-type PbNiO3 undergo antiferromagnetic transition at 225 and 205 K, respectively. Both the perovskite- and LiNbO3-type phases exhibit semiconducting behavior.

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 CO2 and H2O 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 CO2 and H2O 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 CO2 and H2O indicates a high potential in the fabrication of novel types of catalysts and highly selective gas sensors.

Exfoliated graphene ligands were prepared by heating exfoliated graphene sheets in ammonia gas at 1023 K. The functional groups of the functionalized exfoliated graphene ligands were mainly pyridine on the edges of the vacancy defects. Copper cations were coordinated with the ligands. Even after being heated at 773 K, coordinated copper did not show severe agglomeration. On the other hand, copper supported on exfoliated graphene sheets prepared by the conventional method agglomerated and ca. 20 nm of copper oxide was formed. This difference clearly shows that exfoliated graphene ligands stabilized copper cations. (C) 2011 Elsevier Ltd. All rights reserved.

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 super-compression 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 adsorptivities of supercritical CH4 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 CH4 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 CH4 or H-2; the bundled SWCNT showed the highest adsorptivity for supercritical CH4 and H-2. It was clearly shown that these nanostructures of SWCNTs are crucial for supercritical gas adsorptivity.

Water adsorption hysteresis is one of the most important phenomena observed during the interaction of water with hydrophobic surfaces. Adsorption hysteresis in micropores has strong relevance to the structure of adsorbed water. We used three typical models (cluster, monolayer, and uniform distribution structure models) to determine the structure of the water molecules adsorbed in hydrophobic slit-shaped carbon micropores. In each model, stabilization energy profiles were calculated for various fractional fillings by using the interaction potential theory. Simultaneously, molecular dynamics (MD) simulations of water adsorbed in the micropore of 1.1 nm pore width, which shows significant adsorption hysteresis, were performed to determine the kinetics of the observed structural transformations. The transformations between monolayer and cluster were slow, that is, kinetically forbidden at the fractional filling of 0.2 and 0.6, whereas the cluster uniform distribution structure and uniform distribution structure monolayer transformations were kinetically allowed. The kinetically forbidden transformation resulted in the occurrence of metastable structure of adsorbed water and was responsible for the observed adsorption hysteresis.

It is important to tune the sorption behavior of metal organic framework (MOF) materials. Ethanol treatment on the hydrated form of [Cu(bpy)(2)(BF4)(2)], which is a representative flexible MOF showing the fascinating gate phenomenon on CO2 sorption, induces an easier dehydration and a significant decrease in the CO2 gate pressure. The results of IR, X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS) measurements indicated that water molecules in the lattice of the hydrated form can be removed even at room temperature after the ethanol treatment and the basic 2D layered structure remains with a slight interlayer expansion. The results of thermogravimetric (TG) and gas chromatograph/mass spectrometry (GC/MS) analyses and of CO2 sorptions indicated that the change of the gate phenomenon was caused by a trace of residual ethanol molecules included in the structure. Similar phenomena were observed on alcohols with different polarity and molecular size.

Vibrational rotational properties of CH4 adsorbed on the nanopores of single-wall carbon nanohorns (SWCNHs) at 105-140 K were investigated using IR spectroscopy. The difference vibrational rotational bands of the v(3) and v(4) modes below 130K show suppression of the P and R branches, while the Q branches remain. The widths of the Q branches are much narrower than in the bulk gas phase due to suppression of the Doppler effect. These results indicate that the rotation of CH4 confined in the nanospaces of SWCNHs is highly restricted, resulting in a rigid assembly structure, which is an anomaly in contrast to that in the bulk liquid phase.

The quasi-Werner-type copper(II) complex, [Cu(PF(6))(2)(4-mepy)(4)] (1), in which 4-mepy is the 4-methylpyridine ligand, has flexible and polar axial bonds of Cu-PF(6). Flexibility of the Cu-PF(6) bonds induces diverse and unprecedented guest-inclusion structures, such as {[Cu(PF(6))(2)(4-mepy)(4)][Cu(PF(6))(4-mepy)(4)(acetone)]center dot PF(6)center dot 4acetone} (gamma-1 superset of 2.5acetone), {[Cu(PF(6))(2)(4-mepy)(4)][Cu(PF(6))(4-mepy)(4)(2-butanone)]center dot PF(6)center dot 3.5(2-butanone)} (gamma-1 superset of 2.25(2-butanone)), {[Cu(PF(6))(2)(4-mepy)(4)][Cu(PF(6))(4-mepy)(4)(H(2)O)]center dot PF(6)center dot 4benzene} (gamma-1 superset of 0.5H(2)O center dot 2benzene), and {[Cu(PF(6))(2)(4-mepy)(4)]center dot 2benzene} (gamma-1 superset of 2benzene). Exposure of the dense form, alpha-1, to benzene vapor affords the benzene-inclusion complex {[Cu(PF(6))(2)(4-mepy)(4)]center dot 2benzene} (gamma-1 superset of 2benzene), all benzene guests of which are easily removed by vacuum drying, reforming guest-free, dense alpha-1' with smaller sized crystals than alpha-1. In contrast to alpha-1, which shows almost no CO(2) adsorption, alpha-1' adsorbs CO(2) gas with structural transformations, this being the first example that exhibits adsorption of gas in a dense Werner-type complex and a drastic change in adsorption properties depending on the size of the crystals.

The adsorption of cyclohexene with two sp(2) and four sp(3) carbon 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 sp(2) carbon is closer to the pore wall than that of the sp(3) carbon except for the pore width of 0.7 nm, even though the Lennard-Jones size of the sp(2) carbon is larger than that of the sp(3) carbon. Thus, the difference in the interactions of the sp(2) and sp(3) carbon atoms of cyclohexene with the carbon pore walls is clearly observed in this study. The preferential interaction of sp(2) carbon gives rise to a slight tilting of the cyclohexene molecule against the graphitic wall. This is suggestive of a pi-pi interaction between the sp(2) carbon in the cyclohexene molecule and graphitic carbon.

Tailoring electronic properties of single wall carbon nanohorn (SWCNH) is expected to develop the application potential in various fields. SWCNH is efficiently modified with iodine molecules by liquid phase adsorption. The adsorption isotherm of iodine on SWCNH was Langmuirian with the saturated adsorption amount of 185 +/- 10 mg g (1) (coverage 0.18), indicating a specific interaction between SWCNH and iodine. The DC electrical conductivity of SWCNH film prepared by dip-coating method increased with the iodine adsorption amount almost by a factor 10. (C) 2010 Elsevier B. V. All rights reserved.

The structure of single-wall carbon nanohorns has been studied using pulsed neutron diffraction and molecular dynamics. The collected diffraction data have been converted to a real-space representation in the form of the pair correlation function. For computer-generated models consisting of nanocones and single-wall carbon nanotubes of the perfect hexagonal structure and 20-30 angstrom in diameter, the computed diffracted intensities and pair correlation functions are in reasonable agreement with the experimental data. For larger nanohorns of 50 angstrom diameter, Stone-Wales, mono-vacancy and di-vacancy defects have been introduced to fit the experimental data. (C) 2010 Elsevier B.V. All rights reserved.

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

Intensive change in electronic structure of single wall carbon nanotube (SWCNT) bundles is observed, arising from intercalation of naphthalene into the interstitial spaces of the bundles with adsorption from solution. Ultraviolet photoelectron spectroscopy shows a clear increase in the density of states reaching the Fermi level, explicitly indicating pseudometallization of SWCNT by this simple and scalable intercalation method. On the other hand if a nonvolatile pentacene is deposited on the external bundle surface in vacuum, SWCNT shows no similar change in the density of states. © 2010 The American Physical Society.

The quantum sieving effect of D-2 over H-2 is examined at 40 and 77 K by means of experiments and GCMC simulations, for two types of single-wall carbon nanotubes that are distinguishable by their unique entangled structures; (1) a well-bundled SWCNT and (2) loosely-assembled SWCNT produced by the super growth method (SG-SWCNT). Oxidized SWCNT samples of which the so-called internal sites are accessible for H-2 and D-2, are also studied. Experimental H-2 and D-2 adsorption properties on the well-bundled SWCNTs are compared with the simulated ones, revealing that pore-blocking and restricted diffusion of the molecules suppress the high selectivity of D-2 over H-2. The non-oxidized SG-SWCNT assembly shows the highest selectivity among the SWCNT samples, both at 40 and 77 K. The high selectivity of the SG-SWCNT assembly, which is pronounced even at 77 K, is ascribed to their unique assembly structure.

Intensive change in electronic structure of single wall carbon nanotube (SWCNT) bundles is observed, arising from intercalation of naphthalene into the interstitial spaces of the bundles with adsorption from solution. Ultraviolet photoelectron spectroscopy shows a clear increase in the density of states reaching the Fermi level, explicitly indicating pseudometallization of SWCNT by this simple and scalable intercalation method. On the other hand if a nonvolatile pentacene is deposited on the external bundle surface in vacuum, SWCNT shows no similar change in the density of states.

Surface-enhanced Raman scattering (SERS) was applied to detecting pentagon-heptagon pairs, the so-called Stone Wales defect, in single-wall carbon nanotubes (SWCNTs). When a probing laser light was scanned over a SWCNT-dispersed silver surface, two distinct SERS spectra were obtained: (1) temporally stable spectra similar to that of resonance Raman spectra of bulk SWCNTs and (2) temporally fluctuating spectra with additional peaks which were not observed in the non-SERS spectra. The fluctuations in the SERS spectra are discussed in association with dynamic reconstruction of defective structures of SWCNTs (nonhexagonal arrangements of carbon atoms) in the vicinity of SERS-active sites under irradiation of the laser light.

The effect of addition of tetraethylammonium tetrafluoroborate (Et(4)NBF(4)) on the structure of propylene carbonate (PC) confined in slit-shaped carbon nanopores of activated carbon fiber (pore width = 1.0 nm) was studied by synchrotron X-ray diffraction and reverse Monte Carlo simulation PC molecules are randomly packed in the slit carbon nanopores of 1 nm in the absence of Et(4)NBF(4). Addition of Et(4)N(+) and BF(4)(-) ions promotes formation of considerably ordered double layers of PC molecules even in the highly restricted slit pore space. PC molecules call accept these ions efficiently. This structural modulation function of PC molecular assemblies should contribute to the evolution of supercapacitance in carbon nanopores.

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. (C) 2009 Elsevier Ltd. All rights reserved.

The nanoporous structure and catalytic activities of a new nanoporous metallic platinum (NMP) were studied. The SEM image and N(2) adsorption isotherm of NMP indicated that NMP is highly microporous and mesoporous compared with Pt black (PB). The gas-phase reactivity of NMP for the water-formation reaction at 247 K showed that NMP has a catalytic activity that is 1.6-times higher than that of PB after 60 mm and a reaction rate constant that is three-times larger than that of PB. On the other hand, NMP dispersed on a glassy carbon plate (GC) with Nafion (R) 117 showed an electrochemical reactivity towards methanol electro-oxidation that was lower than that of PB on the same GC electrode. However, the poisoning resistance of NMP on the GC electrode was higher than that of PB under the same conditions.

We synthesized a perovskite-type oxynitride, LaTiO2N by nitridation of the oxide precursor under NH3 atmosphere it low temperature all flow rate. We successfully synthesized LaTiO2N at. 1023 K (750 degrees C) under flowing NH3 gas at a rate of 18 dm(3)/h using a handmade rotary furnace form tie amorphous oxide precursor prepared by a sol-gel technique-polymerizable complex method. The average particle size of tie LaTiO2N sample prepared at 1023 K (750 degrees C) (LTON-750) was smaller than for the LaTiO2N sample prepared by I conventional solid-state reaction method at 1223 K (950 degrees C) (LTON-SS). The smallest particle size of LTON-750 was estimated at 20-30 nm. The BET surface area of LTON-750, calculated front the N-2 adsorption isotherm. was 35.0 m(2)/g. This is approximately 2 fillies greater than that of LTON-SS. Furthermore, LTON-750 and LTON-SS demonstrated the ability to adsorb 11, at 77 K. (C) 2009 The Ceramic Society of Japan All rights reserved

Single-wall carbon nanotube (SWCNT) bundles were pillared by fullerene (C-60) by the cosonication of C-60 and SWCNT in toluene to utilize the Interstitial pores for hydrogen storage. C-60-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 H-2 adsorptivity of the C-60-pillared SWCNT bundles was twice that of the original SWCNT bundles, indicating a design route for SWCNT hydrogen storage.

A new catalyst for efficient production of H-2 from CH4 without CO2 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 CH4 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. (C) 2009 Elsevier B. V. All rights reserved.

The ionic solution structure of Ca and Cl ions in slit-shaped hydrophobic nanopores of pore widths w of 0.6, 1.2, and 1.8 nm was studied by canonical Monte Carlo simulation. The ionic solution in the pore of w = 0.6 nm shows unique hydration structure. A pentagonal hydration structure of a Ca ion is observed, being completely different from the bulk ionic solution. The Ca ions are surrounded by a more tightly hydrogen-bonded water molecular shell than the bulk solution. On the contrary, the Cl ions have a more diffuse hydration shell than the bulk solution.

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 CO(2) from mixed gases and in storage of CH(4) owing to easy release of absorbed molecules. (c) 2009 Elsevier Inc. All rights reserved.

N(2) 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 N(2) and Ar adsorption isotherms at 303 K using the ultramicropore volume determined by H(2)O adsorption. The comparative method of experimental and simulated isotherms of supercritical N(2) 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.

I-2 was adsorbed on single-walled carbon nanotube from ethanol solution at 303 K. The I-2 adsorption isotherm was Langmuirian, giving 35 (+/- 10) mg g(-1) of the saturated adsorption amount (coverage 0.06-0.09). The I-2-adsorption treatment of SWCNT bundles reduced the N-2 adsorption amount at 77 K by only 3%; the adsorption amount of supercritical H-2 at 77 K was decreased by 30% because of the I-2-adsorption treatment, indicating the blocking of interstitial pores by adsorbed I-2. These adsorption results indicated the adsorption of I-2 molecules in the narrow interstitial pores. The I-2-adsorption treatment increases the Raman intensity coming from metallic SWCNTs, and the dc electrical conductivity increased by 15% because of the I-2-adsorption treatment, strongly suggesting the presence of charge-transfer interaction between I-2 and SWCNTs irrespective of small coverage by I-2.

A novel perovskite, PbFe1/2V1/2O3 was successfully synthesized tinder 7 GPa. PbFe1/2V1/2O3 exhibits a highly distorted tetragonal perovskite structure (c/a = 1.18) with the disordered arrangement of Fe and V at room temperature. The XPS reveals that the oxidation states of each ion are Pb2+, Fe3+, and V5+, respectively. The large tetragonal distortion is related to not only the presence of Pb2+ ion but also V5+ with an electronic configuration of d(0). No structural phase transition up to 490 K above room temperature was observed by a high-temperature X-ray diffraction experiment. The temperature dependence of magnetic susceptibility exhibits non-Curie-Weiss behavior, which is attributed to the antiferromagnetic interaction between Fe3+-O2--Fe3+ originated from the disordered arrangement of Fe3+ and V5+ ions. (C)2009 The Ceramic society of Japan. All rights reserved.

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 m(2)/g. The highest surface area of the re-activated ACFs was 2930 m(2)/g as determined from an alpha(S)-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 H-2. The amounts of CH4 and H-2 adsorbed were enhanced by 52% and 30%, respectively, as a result of re-activation.

Predominant water adsorption in hydrophobic slit-shaped carbon nanopores begins at a threshold pressure of water vapor. Adsorption of water vapor was faster for pores of 0.7 nm in width than for pores of 1.1 nm in width. The formation of water dimers is the rate-determining step of the water adsorption from analysis of the adsorption kinetics. The adsorption amount from grand canonical Monte Carlo simulation oscillated with the calculation cycle up to an adsorption amount of 30 mg ml(-1) and then steadily increased to an equilibrium adsorption amount. The Gibbs free energy change with the cluster size of water molecules has a barrier for the cluster growth below the critical adsorption density. The snapshot analysis of the grand canonical Monte Carlo simulation showed that formation of nanoscale clusters of water molecules begins just at the critical density of 30 mg ml(-1). Then the nanoscale cluster formation should be essential to induce the predominant adsorption at the threshold pressure corresponding to the critical adsorption density.

We report the use of chemical vapor deposition (CVD) for the bulk production (grams per day) of long, thin, and highly crystalline graphene ribbons (<20-30 mu m in length) exhibiting widths of 20-300 nm and small thicknesses (2-40 layers). These layers usually exhibit perfect ABAB... stacking as in graphite crystals. The structure of the ribbons has been carefully characterized by several techniques and the electronic transport and gas adsorption properties have been measured. With this material available to researchers, it should be possible to develop new applications and physicochemical phenomena associated with layered graphene.

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 Sp(2) to Sp(3) 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 Sp(3) bonding.

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 N-2 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 H-2 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. (c) 2008 Elsevier Inc. All rights reserved.

The crystal structure of [Cu(4,4'-bipyridine)(2)(CF3SO3)(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)(H2O)(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 N-2 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 H-2 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. (C) 2008 Elsevier Ltd. All rights reserved.

A new ternary platinum oxide, CaPtO3 was synthesized under a pressure of 7 GPa and a temperature of 1000 degrees C. The crystal structure of CaPtO3 was determined by Rietveld analysis of the X-ray powder diffraction data. CaPtO3 has a layered CalrO(3)-type structure (orthorhombic, space group: Cmcm), which is the same as that of a post-perovskite MgSiO3 in the Earth's lower mantle. The magnetic susceptibility data indicate that the Pt ion in CaPtO3 is tetravalent in the low spin state with an electron configuration of t(2g)(6)e(g)(0) (S = 0). This finding is consistent with the insulating behavior.