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Transitional metals (M) were dispersed on single. wall carbon nanohorns (M/SWCNHs, M = Fe, Co, Ni, Cu) by simple thermal treatment of the deposited metal nitrate without H-2 reduction. Nanometallic Ni particles on SWCNH were evidenced by high-resolution transmission electron microscopic observation and X-ray photoelectron spectroscopy. The nano-Ni dispersed on SWCNH showed the highest CH4 decomposition activity; the activity of used transitional metals decreases in the order Ni >> Co > Fe >> Cu. On the other hand, the reaction rate over Ni/SWCNH was much larger than that over Ni/Al2O3, and the former provided COx-free H-2 and cup-stacked carbon nanotubes, while Ni/Al2O3 produced COx in addition to H-2. SWCNH was superior to Al2O3 as the catalyst support of Ni for the CH4 decomposition reaction.

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 N-2 and H-2 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.

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 N-2 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 N-2 in the low-pressure region, thereby offering selective adsorptions, reactions, and separations on nanographene edges.

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 SA at around ambient temperatures and shows temperature dependence with an anti-Arrhenius trend: higher adsorption rate with lower temperature.

For the practical use of activated carbon (AC) as an adsorbent of CH4, tightly packed monoliths with high microporosity are supposed to be one of the best morphologies in terms of storage capacity per apparent volume of the adsorbent material. However, monolith-type ACs may cause diffusion obstacles in adsorption processes owing to their necked pore structures among the densely packed particles, which result in a lower adsorption performance than that of the corresponding powder ACs. To clarify the relationship between the pore structure and CH4 adsorptivity, microscopic observations, structural studies on the nanoscale, and conductivity measurements (thermal and electrical) were performed on recently developed binder-free, self-sinterable ACs in both powder and monolithic forms. The monolith samples exhibited higher surface areas and electrical conductivities than the corresponding powder samples. Supercritical CH4 adsorption isotherms were measured for each powder and monolith sample at up to 7 MPa at 263, 273, and 303 K to elucidate their isosteric heats of adsorption and adsorption rate constants, which revealed that the morphologies of the monolith samples did not cause serious drawbacks for the adsorption and desorption processes. This will further facilitate the availability of diffusion-barrier-free microporous carbon monoliths as practical CH4 storage adsorbents.

Water in single-walled carbon nanotubes was found to form nanosized ice-like structures (nanoice) above a water density of 0.5 g mL(-1) in SWCNTs, but nanosized liquid water-like structures (nanowater) formed below that density, i.e., nanoice grows predominantly from nanowater at a low water density of around 0.5 g mL(-1) and room temperature.

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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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 have investigated the applicability of simulations and theoretical techniques for exploring the selectivities of hydrogen isotopes. We have simulated the adsorption isotherms of H(2) 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 H(2) adsorption at 77 K. Moreover, we show that the ideal adsorption solution theory (IAST) can predict the selectivity of D(2) over H(2) 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 D(2) over H(2) 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 H(2) and D(2) in aluminophosphate AlPO(4)-5 at 77 K. Finally, we analyze the selectivity of D(2) over H(2) by IAST with the experimental single-component adsorption isotherms of H(2) and D(2) at 77 K for a variety of adsorbents: AlPO(4)-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.

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.

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.

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.

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.

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.

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.

We report the production of carbon-based xerogel film without the need for supercritical drying. Xerogel samples were characterized with field emission scanning electron microscopy, nitrogen adsorption/desorption at 77 K, Raman spectroscopy, thermogravimetric analysis, and electrical conductivity and cyclic voltammetry measurements. Experimental results reveal that the film is largely crack free and homogeneous in thickness, and, importantly, has high surface area, large nanopore volume, and an excellent performance for electrical charge storage-both per unit mass and unit volume. These results indicate that the film has potential applications for electrical energy storage devices.

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.

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.

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 TiCl4 precursor. The advantages in structural property, porosity, and surface properties (few deficiencies) lead to a much better photocatalytic activity for TiO2 nanoparticles from titanium alkoxide precursor in comparison with those from TiCl4 precursor. (C) 2008 Elsevier Inc. All rights reserved.

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 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.

We fabricated random network films of highly pure single-wall carbon nanotubes (SWCNTs) on flexible polyethylene terephthalate substrate by dip- and spray-coatings and their combination method for application to flexible transparent conducting films (TCFs). The dip-coating treatment was a more efficient method for fabricating the SWCNT-TCFs of high electrical conductivity without drastic drop in the optical transmittance, compared to the spray-coating one. This should be primarily due to more loose contact in intertube and interbundle junctions of the spray-coated SWCNT networks. Although the electrical conductivity of the SWCNT-TCFs was dramatically enhanced as increasing the number of dipping times, the dip-coating treatment with a large number of dipping times considerably reduced the transmittance without corresponding improvement in the electrical conductivity, indicating the patch-wise coating of the SWCNTs. On the other hand, the combination of the spray- and dip-coatings gave a supplementary effect for formation of a highly transparent film of better electrical conductivity. For SWCNT-TCF coated with 100 dipping times, an additional spray-coating dramatically decreased the sheet resistance from 1300 to 340 Omega/square, which is accompanied by slight reduction of the transmittance from 88 to 80%. Therefore, the post spray-coating can efficiently bridge the patch-wise SWCNT networks produced by the successive dip-coating. (C) 2007 Elsevier Inc. All rights reserved.

We synthesized a discrete type of organic-inorganic hybrid crystal [Cu(ina)(2)(NH3)(2)(H2O)(2)] (ina = isonicotinate). The monomer units connect to each other with hydrogen bonds and pi-pi interactions, forming a three-dimensional network. Removal of ammonia and water molecules by vacuum heating treatment induced a substantial change from nonporous to porous crystals. The resultant porous crystals can predominantly adsorb supercritical hydrogen rather than nitrogen vapor at 77 K.

A nano-structured alloy of Ni and Fe was prepared using poly(vinyl alcohol) (PVA) as a polymer precursor, followed by the reduction of Ni2+ and Fe3+ ions to the corresponding metals by heat treatment of the PVA film containing the metal ions under an inert atmosphere. The alloy obtained was characterized by nitrogen adsorption studies, X-ray diffraction and electron microscopy measurements, and by X-ray photoelectron spectroscopy. The nano-structured alloy had the same crystal structure as that of metallic Ni although metallic Fe formed a different structure. The introduction of Fe atoms caused disorder and less crystallinity in the crystal structure of the alloy, whereas Ni atoms tended to maintain the original crystal Structure. Nitrogen adsorption measurements at 77 K showed that the nano-structured Ni-Fe alloy contained mesopores of 4-10 nm in diameter.

A new strategy for the encapsulation of magnetic nanobeads was developed by using the in situ self-assembly of an organic-inorganic hybrid polymer. The hybrid polymer of {[Cu(bpy)(BF(4))(2)(H(2)O)(2)](bpy)}(n) (bpy=4,4'-bipyridine) was constructed on the surface of amino-functionalized magnetic beads and the resulting hybrid-polymer-encapsulated beads were utilized as catalysts for the oxidation of silyl enolates to provide the corresponding a-hydroxy carbonyl compounds in high yield. After the completion of the reaction, the catalyst was readily recovered by magnetic separation and the recovered catalyst could be reused several times. Because the current method did not require complicated procedures for incorporating the catalyst onto the magnetic beads, the preparation and the application of various other types of organic-inorganic hybrid-polymer-coated magnetic beads could be possible.

The experimental adsorption isotherm of N-2 Molecules on mutually isolated single wall carbon nanotubes at 77 K agreed well with the grand canonical Monte Carlo simulated one. The N-2 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.