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The present report describes the preparation of lanthanide-doped colorless magnetic materials based on poly-β-ketoester particles. Monodisperse poly(2-acetoacetoxy ethyl methacrylate) (PAAEM) parti...

Here, we have demonstrated the production of colorless and full-color magnetic nanoparticles based on holmium (Ho)-doped polymers, which could not be achieved with conventional dark brown iron oxid...

Mesoporous organic polymers, including poly(p-phenylene ether-sulfone) (PES), polysulfone (PSF), poly(bisphenol A-carbonate) (PC), and polyvinyl chloride (PVC), were prepared by the previously reported flash freezing method. For the four polymers, the vapor adsorption of water and hydrocarbons (C2H6, C3H8, and C6H14) was examined. PVC showed that the hydrocarbon adsorption was more selective than water adsorption. The isosteric heats of adsorption were determined from the temperature dependence of the vapor adsorption of the hydrocarbons and water. This showed the weak interaction of PVC with water and its stronger (but not too strong) interaction with hydrocarbons. The hydrophobicity and mesoporosity of PVC were determined to be suitable for such selective adsorption of hydrocarbons compared to that of water with low energy consumption during the desorption process of the hydrocarbons. Mesoporous PVC should considered a candidate for the recovery of flammable gases from water/hydrocarbon mixtures.

Potassium carbonate (K2CO3) is recognized as a potential candidate for CO2 capture by flue gas under moist conditions because of its high sorption capacity and low cost. However, undesirable effect...

A Na2CO3–carbon nanocomposite (NaC-NC) was prepared from terephthalic acid and NaOH, and its CO2 capture under moist conditions was examined by thermogravimetric analysis and X-ray diffraction. CO2 capture was repeated twice. The first CO2 capture reaction of bulk Na2CO3 was faster than its second, while the second capture reaction of NaC-NC was faster than its first. This may be because of the nanostructural properties of NaC-NC. The regeneration from NaHCO3 to Na2CO3 of NaC-NC proceeded at a lower temperature than with the bulk NaHCO3. Thus, compared with the bulk Na2CO3, we found that NaC-NC could efficiently capture CO2, increasing the reaction rate and decreasing the regeneration temperature.

Capacity and kinetics of CO2 capture of Na2CO3 were studied to determine the mechanism for CO2 sequestration under ambient conditions. Bicarbonate formation of Na2CO3 was examined by a thermogravimetric analysis (TGA) under various CO2 and water vapor concentrations and the accompanying structural changes of Na2CO3 were demonstrated by X-ray diffraction (XRD). Morphological variations were observed during the reaction of CO2 capture through scanning electron microscope (SEM). Structural changes and morphological variations, which occurred during the course of the reaction, were then connected to the kinetic and exothermic properties of the CO2 capture process from the XRD and SEM measurements. The results showed that the bicarbonate formation of Na2CO3 has two different pathways. For higher CO2 and H2O concentrations, the bicarbonate formation proceeded effectively. However, for lower CO2 and H2O concentrations, the reactions were more complicated. The formation of Na2CO3•H2O from Na2CO3 as the first step, followed by the subsequent formation of Na5H3(CO3)4, and then the bicarbonate formation proceeds. To understand such fundamental properties in CO2 capture of Na2CO3 is very important for utilization of Na2CO3 as a sorbent for CO2 capture.

Separation of CO2 based on adsorption, absorption, and membrane techniques is a crucial technology necessary to address current global warming issues. Porous media are essential for all these approaches and understanding the nature of the porous structure is important for achieving highly efficient CO2 adsorption. Porous carbon is considered to be a suitable porous media for investigating the fundamental mechanisms of CO2 adsorption, because of its simple morphology and its availability in a wide range of well-defined pore sizes. In this study, we investigated the dependence of CO2 adsorption on pore structures such as pore size, volume, and specific surface area. We also studied slit-shaped and cylindrical pore morphologies based on activated carbon fibers of 0.6–1.7 nm and carbon nanotubes of 1–5 nm, respectively, with relatively uniform structures. Porous media with larger specific surface areas gave higher CO2 adsorption densities than those of media having larger pore volumes. Narrower pores gave higher adsorption densities because of deep adsorption potential wells. However, at a higher pressure CO2 adsorption densities increased again in nanopores including micropores and small mesopores. The optimal pore size ranges of CO2 adsorption in the slit-shaped and cylindrical carbon pores were 0.4–1.2 and 1.0–2.0 nm, respectively, although a high adsorption density was only expected for the narrow carbon nanopores from adsorption potentials. The wider nanopore ranges than expected nanopore ranges are reasonable when considering intermolecular interactions in addition to CO2–carbon pore interactions. Therefore, cooperative adsorption among CO2 in relatively narrow nanopores can allow for high density and high capacity adsorption.

We have developed a laser-induced chemical vapor deposition (LCVD) method for preparing nanocarbons with the aid of SF 6 . This method would offer advantages for the production of aggregates of nanoscale foams (nanofoams) at high rates. Pyrolysis of the as-grown nanofoams induced the high surface area (1120 m 2 g −1 ) and significantly enhanced the adsorption of supercritical H 2 (16.6 mg g −1 at 77 K and 0.1 MPa). We also showed that the pyrolized nanofoams have highly ultramicroporous structures. The pyrolized nanofoams would be superior to highly microporous nanocarbons for the adsorption of supercritical gases.

Single-walled carbon nanotubes (SWCNTs) have been recognized as promising nanocarriers by many researchers from around the world through hundreds of articles published in the last decade pertaining to SWCNTs-based drug delivery applications. In line with this issue, systematic studies of non-covalent interaction between camptothecin (CPT) and the oxidized SWCNTs (Ox-SWCNTs) have been done in this work. Through the developed process of purification and acid oxidation, we obtained the Ox-SWCNTs that were essentially free of metals and well dispersed in aqueous solutions. A quenching phenomenon, which is indicative of the interactions between CPT and the Ox-SWCNTs, was observed and used as the basis of analysis for monitoring the adsorption of CPT. A comparison of the kinetic models and the overall adsorption capacity was best described by the pseudo second-order kinetic model and Weber–Morris kinetic model. Langmuir and Freundlich models were introduced to fit the adsorption isotherms data. The adsorption of CPT was found to be dependent on concentration and adsorption temperature. The thermodynamic analysis exhibited that the adsorption of CPT on the Ox-SWCNTs was exothermic and spontaneous.

Recently, various composites for reducing CO2emissions have been extensively studied. Because of their high sorption capacity and low cost, alkali metal carbonates are recognized as a potential candidate to capture CO2from flue gas under moist conditions. However, undesirable effects and characteristics such as high regeneration temperatures or the formation of byproducts lead to high energy costs associated with the desorption process and impede the application of these materials. In this study, we focused on the regeneration temperature of carbon aerogel–potassium carbonate (CA–KC) nanocomposites, where KC nanocrystals were formed in the mesopores of the CAs. We observed that the nanopore size of the original CA plays an important role in decreasing the regeneration temperature and in enhancing the CO2capture capacity. In particular, 7CA–KC, which was prepared from a CA with 7 nm pores, exhibited excellent performance, reducing the desorption temperature to 380 K and exhibiting a high CO2capture capacity of 13.0 mmol/g-K2CO3, which is higher than the theoretical value for K2CO3under moist conditions.

The enhancement of photocatalytic activity of TiO2 can be made either by promoting absorption efficiency of photon energy or by reducing recombination losses of photogenerated charge carriers, for which fabrication of nanocomposite structure with carbon materials is an optional selection. Among various nanocarbons, graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO) are more favorable as the counterpart materials because they can provide availability of both obverse and reverse surface, thus doubling effective sites for adsorption, loading of nanoparticles, and interfacial interaction with the loaded nanoparticles. Composition of G/GO with titania, therefore, is a hopeful strategy for achieving synergy or cooperative effect in photocatalysis. In this personal account, we focus on the background and methodology of several soft chemical approaches that we have utilized up to date to fabricate nanocomposites of G/GO and titania, aiming to shed light on the importance of designing of nanocomposite structure for enhancing photocatalysis. In addition, we emphasize the role of interfacial interaction between carbon and titania by exemplifying a hybridized photocatalyst based on inexpensive biomass-derived carbon sphere (CS), and demonstrate that it is a crucial influential factor underlying an enhanced visible light photocatalysis. CS can be a better selection as a counterpart component than G/GO, whose core-shell composing structure with titania (TiO2 @CS) can efficiently induce charge transfer so as to achieve a much higher photocatalytic performance under visible light illumination as compared to the composite of rGO and titania.

On the basis of the structure of the unimolecular Zn3(OAc)4–3,3′-bis(aminoimino)binaphthoxide complex, a poly-Zn3(OAc)4–3,3′-bis(aminoimino)binaphthoxide (poly-Zn) complex was prepared from 3,3′-diformylbinaphthol, tetramine, and Zn(OAc)2. The first-generation poly-Zn catalyst (poly-Zn1) was prepared from poly(aminoiminobinaphthol) and Zn(OAc)2. Although poly-Zn1 showed high catalytic activity for iodolactonization, the catalyst could not be reused. The second-generation poly-Zn catalyst (poly-Zn2) was prepared by the self-organization of 3,3′-diformylbinaphthol, tetramine, and Zn(OAc)2. This produced a stable and active poly-Zn2 catalyst for asymmetric iodolactonization that was reused over five cycles.

We report XRD and IR measurements of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI–BF4) adsorbed in activated carbons, molecular sieving carbon, and single wall carbon nanohorn, where we specifically chose a wide range of pore sizes from 0.5 nm to 2.5 nm. Electron radial distribution function analysis reveals denser packing upon adsorption in two steps, for pore widths larger and comparable to the ion size. Average ion-distance was decreased by 0.05 nm in the latter case. With support of DFT calculations we identify a suppression of specific vibrational modes, which are interpreted as constrainment by the pore walls. Possible consequences for supercapacitor application are discussed.

The capacity and kinetics of CO2 capture of K2CO3 were studied to determine the mechanism for CO2 sequestration under ambient conditions. Bicarbonate formation of K2CO3 was examined by thermogravimetric analysis under various CO2 concentrations in the presence of water vapor, and the accompanying structural changes of K2CO3 were demonstrated by X-ray diffraction (XRD). Morphological variations were observed during the reaction in the presence of different CO2 concentrations through scanning electron microscopy (SEM). Structural changes and morphological variations, which occurred during the course of the reaction, were then connected to the kinetic and exothermic properties of the CO2 capture process from XRD and SEM measurements. The XRD results showed that the bicarbonate formation process of K2CO3 could be divided into three reactions, such as the formation of K2CO3·1.5H2O from K2CO3, the subsequent formation of K4H2(CO3)3·1.5H2O from K2CO3·1.5H2O, and the slow formation of KHCO3 from K4H2(CO3)3·1.5H2O...

In this study, CO2 occlusion of K2CO3 was examined at different temperatures under moist conditions. The CO2 occlusion rate increased with increasing temperatures, whereas the saturated occlusion amount decreased. The highest occlusion amount (i.e. 6.48 mmol·g–1) was obtained at 313 K. Results of X-ray powder diffraction analysis showed that the formation of bicarbonate as a result of the K2CO3 decomposition with CO2 and H2O involved two reactions with K4H2(CO3)3·1.5H2O as an intermediate. It was determined that the lower saturated occlusion amount at higher temperatures originated from the exothermic property of the second reaction. Because the equilibrium constant for the bicarbonate formation is smaller at higher temperatures, the reaction does not proceed as quickly or efficiently according to Le Châtelier’s principle. Therefore, the CO2 occlusion of K2CO3 is suitable for the saturated occlusion amount at lower temperatures.

The ability of an activated carbon (AC) to adsorb 18 different cytokines with molecular weights ranging from 8 kDa to 70 kDa and high mobility group box-1 (HMGB1) from inflammatory model plasma at 310 K and the mechanisms of adsorption were examined. Porosity analysis using N2 gas adsorption at 77K showed that the AC had micropores with diameters of 1-2 nm and mesopores with diameters of 5-20 nm. All 18 cytokines and HMGB1 were adsorbed on the AC; however, the shapes of the adsorption isotherms changed depending on the molecular weight. The adsorption isotherms for molecules of 8-10 kDa, 10-20 kDa, 20-30 kDa, and higher molecular weights were classified as H-2, L-3, S-3, and S-1 types, respectively. These results suggested that the adsorption mechanism for the cytokines and HMGB1 in the mesopores and on the surface of the AC differed as a function of the molecular weight. On the basis of these results, it can be concluded that AC should be efficient for cytokine adsorption.

Nanostructured silicon (N-Si) was prepared by anodic electroetching of p-type silicon wafers. The obtained magnetic particles were separated by a permanent neodymium magnet as a magnetic nanostructured silicon (mN-Si). The N-Si and mN-Si exhibited different magnetic properties: the N-Si exhibited ferromagnetic-like behaviour, whereas the mN-Si exhibited superparamagnetic-like behaviour.

To develop high-performance activated carbons (ACs) for adsorption heat pumps (AHPs), it is important to characterize the adsorption behaviors of the refrigerant molecules in the pores of ACs. Not only pore structures, such as pore size and shape, but also surface functionalities strongly influences the adsorption behaviors, especially for polar molecules, such as water and ethanol, which are typical refrigerants for AHP. In this study, we examined the influence of surface functional groups on the adsorption behaviors of ethanol molecules in carbon micropores using model ACs with different amounts of oxygen-containing surface functional groups but comparable porosities. For the AC with an increased amount of surface functional groups, ethanol adsorption/desorption isotherms showed significant decreases in the adsorption amounts and shortened adsorption equilibrium times compared to those with less surface functional groups throughout the entire relative pressure region. This suggests diffusional hindrance of ethanol molecules in micropores with abundant surface functional groups. To verify our hypothesis, we examined the influence of surface functional groups on the adsorption behavior of ethanol molecules using a solid-state NMR technique. The NMR results revealed that the hydroxyl group of ethanol molecules strongly interacts with the surface functional groups, giving rise to an oriented adsorption of ethanol molecules in the micropores with oxygen-containing surface functional groups. Furthermore, electrochemical analyses confirmed that diffusion resistance of electrolyte ions in the micropores increases after the introduction of oxygen-containing surface functional groups, which supports our hypothesis.

We fabricated nanoscale BaTiO3 and its asymmetric crystal structure was obtained using an asymmetric reaction field in carbon nanospaces. The nano-crystal phases changed from symmetric to asymmetric crystals with decreasing crystallite size. The fabrication of an asymmetric crystal in a nanospace can be adapted for various ceramic fabrications.

We investigated the importance of the specific effective surface area through a detailed study on the relationship between electrical conductivity of single-walled carbon nanohorns (SWCNHs) and accessibility of the electrolyte ions in the SWCNH-based supercapacitor. After heat treatment of the SWCNHs, the ratio of sp2/sp3 carbons dramatically increased, suggesting an enhanced electrical conductivity of the SWCNHs. Even though the specific surface area (SSA) slightly decreased by 16% as a result of heat treatment, the specific capacitance per SSA of the SWCNH electrode remarkably increased from 22 to 47 μF cm–2. Such a result indicates an explicit increase in accessible effective surface area by electrolyte ions. Our result clearly showed that a higher degree of utilization for the interstitial pore of SWCNHs by solvated ions is a key factor in achieving a high volumetric capacitance of SWCNH-based supercapacitors.

Water in carbon nanotubes (CNTs) displays unique behaviors such as ring-like structure formation, anomalous hydrogen bonds, and fast transportation. We demonstrated the structures and stability of water in loading and release processes using a combination of X-ray diffraction analysis and hybrid reverse Monte Carlo simulations. Water formed nanoclusters in water loading, whereas layered structures were formed in water release. The water nanoclusters formed in water loading were well stabilized in CNTs. In contrast, in water release, the water layers were less stable than the water nanoclusters. The significant stabilization of nanoclusters in water loading and the relatively low stability of water layers in water release suggest easy water loading and release through CNTs, providing sequential water transportation through CNTs.

Electron density of single wall carbon nanotubes (SWCNT) is effectively modified by hexaiodobenzene (HIB) molecules using liquid-phase adsorption. UV-Vis-NIR absorption spectra of the HIB-adsorbed SWCNT, especially in the NIR region, showed a disappearance of S11 transitions between the V1 valance band and the C1 conduction band of van Hove singularities which can be attributed to the effective charge transfer between HIB and the SWCNT. The adsorption of HIB also caused significant peak-shifts (lower frequency shift around 170 cm−1 and higher shift around 186 cm‑1) and an intensity change (around 100–150 cm−1 and 270–290 cm−1) in the radial breathing mode of Raman spectra. The charge transfer from SWCNT to HIB was further confirmed by the change in the C1s peak of X-ray photoelectron spectrum, revealing the oxidation of carbon in SWCNT upon HIB adsorption.

Water plays an important role in controlling chemical reactions and bioactivities. For example, water transportation through water channels in a biomembrane is a key factor in bioactivities. However, molecular-level mechanisms of water transportation are as yet unknown. Here, we investigate water transportation through narrow and wide one-dimensional (1D) channels on the basis of water-vapor adsorption rates and those determined by molecular dynamics simulations. We observed that water in narrow 1D channels was transported 3-5 times faster than that in wide 1D channels, although the narrow 1D channels provide fewer free nanospaces for water transportation. This rapid transportation is attributed to the formation of fewer hydrogen bonds between water molecules adsorbed in narrow 1D channels. The water-transportation mechanism provides the possibility of rapid communication through 1D channels and will be useful in controlling reactions and activities in water systems.

On the basis of the structure of the unimolecular Zn3(OAc)4–3,3′-bis(aminoimino)binaphthoxide complex, a poly-Zn3(OAc)4–3,3′-bis(aminoimino)binaphthoxide (poly-Zn) complex was prepared from 3,3′-diformylbinaphthol, tetramine, and Zn(OAc)2. The first-generation poly-Zn catalyst (poly-Zn1) was prepared from poly(aminoiminobinaphthol) and Zn(OAc)2. Although poly-Zn1 showed high catalytic activity for iodolactonization, the catalyst could not be reused. The second-generation poly-Zn catalyst (poly-Zn2) was prepared by the self-organization of 3,3′-diformylbinaphthol, tetramine, and Zn(OAc)2. This produced a stable and active poly-Zn2 catalyst for asymmetric iodolactonization that was reused over five cycles.

Nanoscale confined electrolyte solutions are frequently observed, specifically in electrochemistry and biochemistry. However, the mechanism and structure of such electrolyte solutions are not well understood. We investigated the structure of aqueous electrolyte solutions in the internal nanospaces of single-walled carbon nanotubes, using synchrotron X-ray diffraction. The intermolecular distance between the water molecules in the electrolyte solution was increased because of anomalously strong hydration shell formation. Water correlation was further weakened at second-neighbor or longer distances. The anomalous hydrogen-bonding structure improves our understanding of electrolyte solutions in nanoenvironments.

High-density CH4 storage using adsorption techniques is an important issue in the use of CH4 as a clean energy source. The CH4 adsorption mechanism has to be understood to enable innovative improvements in CH4 adsorption storage. Here, we describe the adsorption mechanism, based on CH4 structure, and stabilities in the internal and external nanopores of single-walled carbon nanohorns, which have wide and narrow diameters, respectively. The adsorption of larger amounts of CH4 in the narrow nanopores at pressures lower than 3 MPa was the result of strong adsorption potential fields; in contrast, the wider nanopores achieve higher-density adsorption above 3 MPa, despite the relatively weak adsorption potential fields. In the wider nanopores, CH4 molecules were stabilized by trimer formation. Formation of CH4 clusters therefore compensates for the weak potential fields in the wider nanopores and enables high-density adsorption and adsorption of large amounts of CH4.

In this study, we investigated the possibilities of using activated carbon fibre (ACF) as a carbon capture and storage (CCS) technology. The CO2 adsorption isotherms of ACFs with different porosities were systematically examined at 273 and 298 K under ambient pressure conditions. The porosities of the ACFs were characterized by the adsorption of nitrogen at 77 K. We analyzed the adsorption capabilities of three types of ACFs (A5, A10 and A20) having different slit-shaped pore widths, specific surface areas and micropore volumes. Our results reveal that A5 had ultramicropores and achieved a higher adsorption of CO2 at low relative pressure (

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.

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.