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The separation of propane and propylene is the most energy-consuming and difficult separation process in the petrochemical industry because of their extremely similar physical properties. Separating propylene from propane using sorption can considerably reduce the energy consumed by current cryogenic distillation techniques. However, sorption involves several major challenges. An elastic layer-structured metal-organic framework (ELM-11) exhibited a highly efficient propane/propylene sorption separation, owing to its kinetic properties. Under equilibrium conditions, propane and propylene exhibited similar sorption capacities, gate opening pressures, and heats of sorption. Thus, their separation under equilibrium conditions is impractical. However, the sorption rates of the two gases were considerably different, showing different diffusion coefficients, resulting in a high kinetic selectivity (214 at 298 K) of propylene over propane on ELM-11. This kinetic selectivity is considerably higher than those obtained in previous studies. Thus, ELM-11 is a promising sorbent for separation technologies.

Abstract Here, an unprecedented phenomenon in which 7‐coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated H₂O molecules, form micellar cubic mesophases at room temperature, creating body‐centered cubic (BCC)‐type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self‐assembling behavior of 6‐coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions. Since the magnetic and luminescent properties of different lanthanides vary, adding arbitrary functions to spherical arrays is possible by selecting suitable lanthanides to be used. The method developed in this study using 7‐coordinate lanthanide metallomesogens as building blocks is expected to lead to the rational development of micellar cubic mesophases.

In this study, we show that doping lanthanides into lamellar crystals reorganizes the lamellar structure and dramatically changes the crystal morphology. Azo-DA, a compound with azobenzene derivatives and carboxylic acids at both ends of the diacetylene moiety, formed plate-like lamellar crystals. The doping of holmium (Ho), a lanthanide, into the film obtained by stacking Azo-DA lamellar crystals, promoted a dramatic change in crystal morphology, resulting in the formation of an Azo-DA/Ho film with a radial lamellar crystal structure. A detailed investigation of the crystal growth process revealed that Azo-DA/Ho, which is slightly formed in the solution phase during Ho doping, acts as a pseudonucleating agent and dramatically changes the morphology of the lamellar crystals. Additionally, the morphological changes in the lamellar crystal films significantly changed the surface properties of the films, such as their appearance and water repellency. Similar morphological changes in lamellar crystals were induced when other lanthanide elements were used instead of Ho, and the type of lanthanide dopant can affect the magnetic properties of the films.

Elastic layer-structured metal–organic frameworks (ELMs) have flexible structures. ELM-11 shows the gate phenomenon on CO2 sorption–desorption, and ELM-12 shows the double-step sorption of N2 at 77 K, but the CO2 sorption of ELM-12 has not been investigated in detail. Calorimetric measurements of the heats of sorption and desorption enable analysis of the sorption mechanism and behavior. The heats of sorption, desorption, and the gate phenomenon for ELM-11 and -12 were obtained calorimetrically and compared with those obtained using the van 't Hoff and Clausius–Clapeyron equations. The sorption heat was greater than that of CO2 liquefaction, despite the destabilization of the ELM resulting from interlayer expansion. Further, the heat was similar to that evaluated using van 't Hoff plots. The rapid uptake and fast rate of CO2 sorption resulting from the gate phenomenon yielded an energetically favorable process and more effective heat exchange than those of existing adsorbents, which show modest adsorption rates. Therefore, ELM-11 has applications in heat management for gas sorption. Unlike ELM-11, ELM-12 did not show gated CO2 sorption below 760 Torr but, instead, the open micropores were filled. In addition, the heat of adsorption was higher than that of the sublimation of CO2.

Holmium (Ho) is a lanthanide element with a high magnetic moment. Here, we create an amorphous metal-organic framework (MOF) that has no long-range periodic order but retains the basic components of MOF by using isophthalic acid as an organic linker and Ho as a metal species. The resulting spherical Ho-MOF particles disperse well in a solvent and exhibit excellent magnetic properties in response to magnets. Since Ho has almost no coloring, Ho-MOF particles are a colorless magnetic material, unlike conventional iron oxide particles. Taking advantage of the colorless property, the selective adsorption of dyes on Ho-MOF particles can be easily visually confirmed by magnetically separating the particles. In addition, present versatile processes that enable adaptation of lanthanide elements other than Ho enable the development of colorless multifunctional MOF particles.

The present report describes the preparation of lanthanide-doped colorless magnetic materials based on poly-beta-ketoester particles. Monodisperse poly(2-acetoacetoxy ethyl methacrylate) (PAAEM) particles were prepared by dispersion polymerization using AAEM as the monomer in the presence of a cross-linker. Because of the swelling characteristics of the cross-linked PAAEM particles in solvent, the lanthanide was effectively doped inside the particles, and the distribution of the lanthanides in the particles was visualized. By creating terbium (Tb)-doped PAAEM particles (PAAEM/Tb), which has luminescence properties in addition to magnetic properties, the relationship between efficient lanthanide doping conditions and magnetism was clarified. Because of the low coloration of lanthanides, the resulting PAAEM/Tb particles were colorless magnetic materials compared with conventional iron oxide magnetic nanoparticles. Magnetic force microscope measurements revealed that each particle exhibited magnetism. In addition, because of the high dispersibility of PAAEM/Tb particles and their colorless nature, the inkjet printing of particles and preparation of composites with commodity polymers have been demonstrated. The present technique has been shown to be widely applicable to other lanthanides instead of Tb. This versatile process enables the development of colorless functional polymeric materials with magnetic properties.

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 oxide magnetic nanoparticles. The coordination of Ho, a lanthanide with low colorability and a strong magnetic moment, with a poly(2-acetoacetoxy ethyl methacrylate) brush built on the surface of submicron-sized silica particles allowed for the formation of colorless magnetic nanoparticles. Additionally, bright and full-color magnetic nanoparticles were obtained by mixing different colored magnetic nanoparticles that were prepared by copolymerization of 2-acetoacetoxy ethyl methacrylate and dye monomers. Various colors, including transparency, were demonstrated by means of the present method, which determines the presence or absence of magnetism by Ho doping. The bright and magnetically controllable colored nanoparticles presented herein may have a significant impact on practical substances and applications, such as ink and biomedical and device applications.

[Cu(4,4 '-bipyridine)(2)(BF4)(2)] (ELM-11), an elastic layer-structured MOF (metal-organic framework), is expected to be a sophisticated CO2 reservoir candidate because of its high capacity and recovery efficiency for CO2 sorption. While ELM-11 shows a unique double-step gate sorption for CO2 gas, the dynamics of the structural transition have not yet been clarified. In this study, the dynamics of the 4,4 '-bipyridine linkers and the BF4- anions were studied by determining H-1 spin-lattice relaxation times (T-1). The ELM-11 structural transition accompanying CO2 sorption was also examined through the CO2 uptake dependence of the H-1 spin-spin relaxation time (T-2), in addition to T-1. In its closed form, the temperature dependence of the H-1 T-1 of ELM-11 was analyzed by considering the contributions of both paramagnetic and dipolar relaxations, which revealed the isotropic reorientation of BF4- and the torsional flipping of the 4,4 '-bipyridine moieties. The resultant activation energy of 32 kJ mol(-1) for the isotropic BF4- reorientation is suggestive of strong (B-F...Cu2+) interactions between Cu(II) and the F atoms in BF4-. Furthermore, the CO2 uptake dependence of T-1 was found to be dominated by competition between the increase in the longitudinal relaxation time of the electron spins and the decrease in the spin density in the unit cell.

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.

Flexible porous materials have great potential for adsorption/separation of small molecules. In this study, a highly CO2-selective two-dimensional (2D) layered metal-organic framework (MOF) showing gate-type adsorption properties was synthesized and fully characterized by single-crystal X-ray diffraction (XRD), in situ powder XRD, thermogravimetric analysis, inductively coupled plasma atomic emission spectroscopy, and gas adsorption/separation analyses. The MOF named ELM-13 is a 2D layered material functionalized with (trifluoromethyl)trifluoroborate to control interlayer interactions and exhibits dynamic guest accommodation/removal properties. In a gas adsorption study, the MOF showed no adsorption at low pressure followed by abrupt uptake and sudden desorption at a pressure lower than that of adsorption, i.e., gate adsorption, in the N-2, O-2, Ar, NO, and CO2 isotherms at the boiling/sublimation temperature of each gas. The structure of the MOF in the CO2 adsorption was influenced by both the amount adsorbed and the adsorption process. High-pressure adsorption experiments at 273 K indicated that, out of N-2, O-2, Ar, and CO2, only CO2 was adsorbed on the MOF below 900 kPa. The CO2 selectivity from an equimolar CO2/N-2 mixture with a total gas pressure of 1 MPa at 273 K was experimentally evaluated and compared with the CO2 selectivities of other selected porous materials theoretically, suggesting that ELM-13 is a good candidate for CO2 separation.

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 effects and characteristics that are associated with the desorption process, such as the slow reaction rate and the high regeneration temperature, lead to high energy costs and thus hinder its application. To improve the CO2 capture properties of K2CO3 under moist conditions, we investigated in this study the reaction rate and the regeneration temperature of a K2CO3 -carbon composite (KC-CC), which was prepared from terephthalic acid and KOH. The successful synthesis of KC-CC was confirmed by the X-ray diffraction and Raman spectrometry results, while the CO2 capture characteristics of KC-CC under moist conditions were examined by thermogravimetric analysis. The CO2 capture experiment was repeated twice. The CO2 capture by KC-CC was faster than that by bulk K2CO3, while after the CO2 capture, the regeneration proceeded at lower temperatures compared to bulk KHCO3. Moreover, after a 10-cycle repetition of the CO2 capture experiment, KC-CC exhibited a stable performance. Thus, compared to bulk K2CO3, KC-CC could efficiently capture CO2 at an increased reaction rate and a lower regeneration temperature. This may be due to the nanostructural properties of KC-CC, which were also indicated by the results of XRD analysis.

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.

Nanostructured silicon (N-Si) was prepared by anodic electro-etching 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.

Capacity and kinetics of CO2 capture of Na-2 CO3 were studied to determine the mechanism for CO2 sequestration under ambient conditions. Bicarbonate formation of Na-2 CO3 was examined by a thermogravimetric analysis (TGA) under various CO2 and water vapor concentrations and the accompanying structural changes of Na-2 CO3 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 Na-2 CO3 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 Na-2 CO3 center dot H2O from Na-2 CO3 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 Na-2 CO3 is very important for utilization of Na-2 CO3 as a sorbent for CO2 capture. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

A double-step CO2 sorption by [Cu(4,4'-bpy)(2)(BF4)(2)] (ELM-11) was observed during isothermal measurements at 195, 253, 273, and 298 K and was accompanied by interlayer expansion in the layered structure of ELM-11. The first step occurred in the range of the relative pressure (P/P-0) from 10(-3) to 10(-2). The second step was observed at P/P-0 approximate to 0.3 at the four temperatures. Structural changes in ELM-11 during the CO2 sorption process were examined by X-ray diffraction (XRD) measurements. The structural change for the first step was well understood from a detailed structural analysis, as reported previously. The XRD results showed further expansion of the layers during the second step as compared to the already expanded structure in the first step, and both steps were found to be caused by the gate phenomenon. The energy for the expansion of the layer structure was estimated from experimental and simulated data.

We have developed a laser-induced chemical vapor deposition (LCVD) method for preparing nanocarbons with the aid of SF6. 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. (C) 2016 Elsevier B.V. All rights reserved.

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. (C) 2015 Elsevier B.V. All rights reserved.

Recently, various composites for reducing CO2 emissions have been extensively studied. Because of their high sorption capacity and low cost, alkali metal carbonates are recognized as a potential candidate to capture CO2 from 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 CO2 capture 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 CO2 capture capacity of 13.0 mmol/g-K2CO3, which is higher than the theoretical value for K2CO3 under moist conditions.

On the basis of the structure of the unimolecular Zn-3(OAc)(4)-3,3-bis(aminoimino)binaphthoxide complex, a poly-Zn-3(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. (C) 2015 Elsevier B.V. All rights reserved.

SF6 and SF6-N-2 mixed gases are used widely as insulators, but such gases have high greenhouse gas potential. The separation of SF6 from SF6-N-2 mixed gases is an inevitable result of their use. Single-walled carbon nanohorns (CNHs) were used here for a fundamental study of the separation of SF6 and N-2. The diameters of the interstitial and internal nanopores of the CNHs were 0.7 and 2.9 nm, respectively. The high selectivity of SF6 over N-2 was observed only in the low-pressure regime in the interstitial 0.7 nm nanopores; the selectively was significantly decreased at higher pressures. In contrast, the high selectivity was maintained over the entire pressure range in the internal 2.9-nm nanopores. These results showed that the wide carbon nanopores were efficient for the separation of SF6 from the mixed gas.

The capacity and kinetics of CO2 capture of K2CO3 were studied to determine the mechanism for CO2 sequestration under ambient conditions. Bicarbonate formatioft 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 MID results showed that the bicarbonate formation process of K2CO3 could be divided into three reactions, such as the formation of K2CO3 center dot 1.5H(2)O from K2CO3, the subsequent formation of K4H2(CO3)(3)center dot 1.5H(2)O from K2CO3 center dot 1.5H(2)O, and the slow formation of KHCO3 from K4H2(CO3)(3)center dot 1.5H(2)O. The SEM observations showed that the morphology of the particles at all three stages played a crucial role in the kinetic behavior for CO2 sorptivity of K2CO3. CO2 capture of K2CO3 was inhibited under a concentrated CO, atmosphere during the initial stage, consisting of the first and second reactions, but the formation of KHCO3 from K4H2(CO3)(3)center dot 1.5H(2)O was thermodynamically favorable upon the increase of the CO2 concentration.

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)center dot 1.5H(2)O 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 Chatelier'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 310K and the mechanisms of adsorption were examined. Porosity analysis using N-2 gas adsorption at 77 K 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. (C) 2014 Elsevier B.V. All rights reserved.

Adsorption of lysozyme on carbon nanospaces was studied by measurement of structures and biological activities of the adsorbed lysozyme. Carbon aerogel (CA) was used as the carbon material. Several kinds of CAs with different pore sizes were prepared. Porosities of CAs were characterized by a nitrogen adsorption measurement at 77 K. Adsorption measurements showed that mesopores with diameters between 15 and 25 nm were the most suitable for lysozyme adsorption. However, because the size of lysozyme is less than 5 nm in length, this adsorption behaviour suggests that lysozyme molecules may associate with one another to form clusters on mesopores of CAs. This is a unique behaviour because it is well-known that lysozyme indicates monolayer adsorption on the flat surface. The X-ray diffraction patterns of lysozyme-adsorbed CA showed a few peaks originating from the structure of lysozyme. The strongest peak of a bulk species of lysozyme was shifted by heating because of changes in its secondary structures. Lysozyme-adsorbed CA showed behaviours different from that of bulk species of lysozyme on heating. The recovery of biological activity of lysozyme denatured by heating was promoted by CA. Thus, hydrophobic mesopores of CA influence the stability of the structure of lysozyme.

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. (C) 2014 Elsevier Ltd. All rights reserved.

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 sp(2)/sp(3) 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 mu F 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.

Fabrication of monolayer graphene is a challenge and many processes yield few-layer or multi-layer graphene materials instead. The layer number is an important property of those materials and a quality control variable in graphene manufacture. We demonstrated that N2 adsorption on graphene materials was used to distinguish its layer number. We performed grand canonical Monte Carlo simulation of N2 adsorption on graphene materials with 1-10 layers to indicate the possibility of distinction of layer number by evaluating the dependence of N2 adsorption characteristics on the layer number of graphene materials as well as the adsorption mechanism. The threshold relative pressures of monolayer adsorption of N2 on monolayer and two-layer graphene were 1 × 10-3 and 2 × 10-4, respectively, while those of the others were 1 × 10 -4. In contrast, the threshold pressures of second layer adsorption of N2 were similar to each other. The difference of threshold pressures is attributed to stabilized energies induced by interactions with graphene materials. Therefore, the layer number of graphene materials could be evaluated from the threshold pressures of adsorption, providing a guide to aid fabrication of graphene materials. © 2013 Elsevier Ltd. All rights reserved.

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.

We report the vertical alignment of propylene carbonate (PC) molecules interacting with Et4N+ and BF4- which are confined in extremely narrow slit pores (w similar to 0.7 nm) of carbide-derived carbon and pitch-based activated carbon fiber. On the basis of X-ray diffraction (XRD), electron radial distribution function analysis reveals that the nearest PC-PC distance is 0.05-0.06 nm shorter than that in the bulk solution, indicating dense packing of PC molecules in the pores. This confinement effect results from the vertically aligned PC molecules, which are indicated by the reverse Monte Carlo analysis. The ensemble structure of PC molecules in the subnanometer carbon pores will provide better understanding the supercapacitor function.

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 S-11 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.

The hydration structure of NaCl aqueous solution was elucidated in carbon nanotubes (CNTs) on the basis of canonical ensemble Monte Carlo simulations. Hydration shells were preferentially formed even in narrow CNTs to gain stabilization energy, whereas hydrogen bonding between water molecules in such CNTs was sacrificed. Nanoscale-confined aqueous electrolyte solutions therefore prioritize hydration shell formation between ions and water rather than hydrogen-bond formation between water molecules.

The facile synthesis of an organic electric conducting nanowire is described. The simple oxidation of 9-methylcarbazole by iron(III) perchlorate in a methanol/acetonitrile mixture under atmospheric pressure and temperature produces abundant nanowires without using a template. The nanowire consists of 9,9'-dimethyl-3,3'-dicarbazyl and has a rectangular nanowire shape with an average diameter of 397 +/- 50 nm and length of 17 +/- 5 mu m. The results of the elemental analysis, H-1 NMR, FT-IR, XPS, and ESR measurements revealed that the chemical composition of the nanowire is (dicarbazyl)(0.12)(dicarbazylium center dot ClO4-)(0.88)center dot H2O. This result, combined with the UV-vis-NIR measurement, demonstrates that 9,9'-dimethyl-3,3'-dicarbazyl stacks in a mixed valence state. The nanowire is electroactive and has an electric conductivity of 3.0 X 10(-5) S cm(-1).

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.

The quantum molecular sieving effects of pore-structure-controlled single-walled carbon nanotubes (SWCNTs) for H-2 and D-2 were evaluated at 20, 40, and 77 K. The adsorption amounts of D-2 were larger than those of H-2. The lower the adsorption temperature, the greater the difference between the D-2 and H-2 adsorption amounts. Bundled SWCNTs with interstitial pores of diameter 0.6 nm gave the greatest adsorption difference between D-2 and H-2 per unit pore volume. Diffusion-dominated behavior was observed in the low-pressure region at 20 and 40 K as a result of lower mobility. Bundled SWCNTs with only interstitial pores provided a significant quantum molecular sieving as a result of strongly interacting potential wells.

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.

Deposited and heat-treated phthalocyanines are promising electrocatalysts for replacing platinum in the oxygen reduction reaction (ORR), the most important process in energy conversion systems such as fuel cells; and yet its key mechanistic features are not well understood. To optimize their use, it is necessary to understand their behavior in the absence of an electric field. In the pursuit of this goal, we pyrolyzed metal-free, cobalt and copper phthalocyanines between 550 and 1000 degrees C and studied their structural and chemical changes by elemental analysis, N-2 and CO2 adsorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray analysis fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS). Their catalytic activity was assessed by non-isothermal O-2 gasification and NO reduction reactions. A comparison of these results with their other properties allowed us to reach the following conclusions: (i) the loss of reactivity of metal-free phthalocyanine with heat treatment is attributed to its structural annealing and heteroatom loss, with the porosity changes having no effect; (ii) for metal phthalocyanines at intermediate heat treatment temperatures, the optimum in reactivity correlates with the micropore surface area and the presence of metal particles, with no influence of nitrogen content; (iii) the coordination metal increases phthalocyanine thermal stability in an inert atmosphere, but in an oxidizing atmosphere it acts as a gasification catalyst even below decomposition temperatures. The implications of these findings for catalytic oxygen-transfer mechanisms are discussed. (C) 2012 Elsevier Ltd. All rights reserved.

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 (<0.015) at 273 K. However, A10, which had an average pore width of 0.9 nm, exhibited the highest adsorption capacity of 195 mg g(-1) at a higher pressure of about 100 kPa, which is a relatively high value compared with that of conventional activated carbon. By establishing the temperature dependence of CO2 adsorptivity and using Dubinin-Radushkevich analysis, we characterized the interaction energy between pores and CO2 molecules. Our results shed light on the fundamental aspects of CO2 adsorption of ACFs, moving them towards being a viable CCS.

The role of surface functionality on silica and carbonaceous materials for adsorption of cadmium(II) was examined using various mesoporous silica and activated carbon. Silica surfaces were principally functionalized by mono-amino- and mercapto-groups, while carboxylic group was introduced to the activated carbons by oxidation. Functional groups on silica surface were formed using grafting and co-condensation techniques in their preparation. Mono-amino group was found more effective than di-and tri-amino groups for cadmium(II) adsorption on the grafted silica. Mono-amino groups prepared by co-condensation adsorbed cadmium(II) as much as 0.25 mmol/g compared to mercapto- and carboxyl-groups which adsorbed around 0.12 mmol/g, whereas Langmuir adsorption affinities were as strong as 50-60 L/mmol for all of the three functions. The working pH range was wider for mercapto- and carboxyl-functions than for amino-group. Basic site could be an adsorption center for amino-functional groups while ion exchange sites were found to work for the mercapto- and carboxyl-functions to adsorb cadmium(II) from aqueous phase. Based on the experimental results, surface functional groups rather than structure of silica and carbon seemed to play a decisive role for cadmium(II) adsorption. (C) 2012 Elsevier B.V. All rights reserved.

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

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