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Enhanced hydrogen spillover on molecular fullerene C60, which represents extremely curved graphene sheets, is experimentally demonstrated around ambient temperature. Since the spillover hydrogen is strongly attracted by C60, the increase of C60 mass can be directly confirmed by mass spectroscopy. [ABSTRACT FROM AUTHOR]

With the aim of understanding three-dimensional graphene-based frameworks in detail, a realistic structure model of zeolite-templated carbon (ZTC) is constructed by using computer simulation, and its simulated physical properties are compared with experimental data. The proposed structure model provides the insight into a unique X-ray diffraction pattern of ZTC: disordered building units comprised of curved and non-stacked graphene fragments are connected along the ordered zeolite nanochannels, forming a long-range structure order derived from zeolite (111) and (220) planes. Though ZTC is one of the superporous carbons with a very large Brunauer–Emmett–Teller (BET) surface area (3935 m 2  g −1 ), the simulation study indicates a possibility to achieve further higher BET surface area up to 4845 m 2  g −1 . Moreover, the presence of carbon polygons other than hexagon in graphene matrices is analyzed by a high-resolution pair distribution function obtained from neutron diffraction measurement. The comparison between experimental data and simulation suggests that ZTC framework contains a diverse range of carbon polygons such as hexagons, heptagons and octagons, while pentagons are minor. Such distribution of carbon polygons demonstrates interesting similarity between the real three-dimensional graphene-based framework and imaginary ones like Mackay crystals and carbon Schwarzites. [ABSTRACT FROM AUTHOR]

Nanoporous materials, such as zeolites, activated carbons, and metal-organic frameworks (MOFs), are peculiar platforms in which a variety of guest molecules are stored, reacted, and/or separated. The size of the nanopores is essential to realize advanced functions. In this work, we demonstrate a very simple but innovative method for the control of nanopore size, that is, reversible and continuous control by mechanical force loaded to soft nanoporous materials. The elastic properties of several microporous materials, including zeolites, zeolite-templated carbon (ZTC), activated carbon, and MOFs (e.g., ZIF-8), are examined and it is found that ZTC is a material that is suitable for the aforementioned idea thanks to its extraordinary soft properties compared to the others. The original pore size of ZTC (1.2 nm) can be contracted to 0.85 nm by using a relatively weak loading force of 135 MPa, whereas the other microporous materials barely contracted. To demonstrate the change in the physical properties induced by such artificial deformation, in situ gas adsorption measurements were performed on ZTC with and without loading mechanical force, by using CO2, CH4, and H2, as adsorbates. Upon the contraction by loading 69 or 135 MPa, CO2 adsorption amount is increased, due to the deepening of the physisorption potential well inside the micropores, as proved by the increase of the heat of adsorption. Moreover, the adsorption amount is completely restored to the original one after releasing the mechanical force, indicating the fully reversible contraction/recovery of the ZTC framework against mechanical force. The experimental results are theoretically supported by a simulation using Grand Canonical Monte Carlo method. The similar adsorption enhancement is observed also on CH4, whereas H2 is found as an exception due to the weak interaction potential. [ABSTRACT FROM AUTHOR]

Abstract: To evaluate the adsorption sites of hydrogen atom on buckybowl-like molecule (C36H12), which is a model fragment structure of zeolite-templated carbon (ZTC), we have performed path integral molecular dynamics (PIMD) simulation including thermal and nuclear quantum fluctuations under the semi-empirical PM3 potential. Here we have picked up ten carbons as the adsorption sites of additional hydrogen atom (H*), which are labeled as α-, β1-, β2-, γ-, and δ-carbon from edge to bottom carbon for inside and outside of C36H12, respectively. In the static PM3 calculation and conventional MD simulation the ten stable adsorption sites of H* are obtained both inside and outside of C36H12. In PIMD simulation, on the other hand, the nine stable adsorption sites are obtained, except for δ-carbon for inside of C36H12. This result is due to the fact that the thermal effect and zero point vibration of δ-carbon and H* stretching motion make adsorbed hydrogen atom go over potential barrier from δ- and β1-carbon for inside of C36H12 more readily. The thermal and nuclear quantum effects are important to evaluate the hydrogen adsorption site on carbon materials. [ABSTRACT FROM AUTHOR]

In the study to examine effects of three-dimensional (3D) film connectivity on superfluid He film in the pore network, we have measured heat capacities of He film adsorbed in zeolite templated carbon (ZTC), which is an assembly of graphene fragments and has network of 1.2 nm pore with the 3D period of 1.4 nm, shorter than those of nanoporous materials studied so far. From the heat of desorption, the He film adsorbed in ZTC was observed to be formed up to about 1.4 atomic layers. Heat capacities of the He film are rather similar to those on SiO-based porous materials than those on graphite, except for large heat capacities of monolayer He film. At low coverages, the heat capacity rapidly decreases below a temperature T, suggesting a localized state of He at T< T. The T almost monotonically lowers with increasing the coverage. Heat capacity isotherms show maxima around 1.1 layers, which suggests quantum degenerate fluid (Bose fluid) above the coverage. From these results, the phase diagram of He film adsorbed in ZTC has been determined. [ABSTRACT FROM AUTHOR]

Abstract: Ordered microporous carbon that was synthesized in the nanochannels of zeolite Y is characterized by an extremely large surface area, surprisingly uniform micropores and a long-range periodicity originating from the parent zeolite. However, the molecular structure of this zeolite templated carbon (ZTC) has been completely unknown. In this study, an attempt was made to construct a possible molecular model for ZTC. The proposed model is made up of buckybowl-like nanographenes assembled into a three-dimensionally regular network, which reflects all the experimental results obtained from Raman spectroscopy, electron energy-loss spectroscopy, and previously obtained analyses with several other means. Starting from this idealized model, possible forms of defects that would be included in the actual ZTC were also investigated. Moreover, the amount and the type of oxygen functional groups were analyzed and, as per the results, some functional groups were bound to the edge sites of each buckybowl unit in the molecular model. The elemental composition, pore curvature, pore size and pore volume and surface area estimated from such oxygen-containing model agree well with the corresponding experimentally obtained results. The present model can be considered as a reasonable starting point for future refinements of the structure of this quite novel carbon material. [Copyright &y& Elsevier]

Zeolite-templated carbon is a promising candidate as an electrode material for constructing an electric double layer capacitor with both high-power and high-energy densities, due to its three-dimensionally arrayed and mutually connected 1.2-nm nanopores. This carbon exhibits both very high gravimetric (140-190 F g-1) and volumetric (75-83 F cm-3) capacitances in an organic electrolyte solution. Moreover, such a high capacitance can be well retained even at a very high current up to 20 A g-1. This extraordinary high performance is attributed to the unique pore structure. [ABSTRACT FROM AUTHOR]

Zeolite‐templated carbon  is extraordinarily flexible and behaves as a kind of elastic microporous material, unlike other microporous materials, such as activated carbons, zeolites, and metal–organic frameworks. Its uniform micropores (1.2 nm) can be contracted/recovered reversibly just by loading mechanical force, and such pore‐size change induces noticeable increase in gas‐physisorption amount. For more details see the Full Paper by H. Nishihara et al. on page 13009 ff. [ABSTRACT FROM AUTHOR]

We report on nuclear magnetic resonance (NMR) study of zeolite-templated carbon (ZTC) material. Analysis of 13 C and 1 H NMR spectra shows that its structure includes a condensed aromatic ring system and reveals hydrogen atoms bound to aromatic carbons. Small amount (∼3%) of sp 3 carbons is also detected. The proposed ZTC structure consists of large conductive graphene units connected by carbon hexagons and rare sp 3 carbon links. Such structure keeps electrical conduction throughout the carbon network by means of conductive sp 2 carbon bridges and a charge hopping through the short non-conductive sp 3 carbon links. [ABSTRACT FROM AUTHOR]

For the first time, we present in this work a simple method to achieve high energy density device by functionalizing zeolite-templated carbon (ZTC) with quinone molecules. Two types of quinone, anthraquinone and tetrachlorohydroquinone, which have different redox potential, were introduced into ZTC framework by a wet impregnation method, and were characterized in a sulfuric acid. An organic proton battery was assembled from two different functionalized-ZTC electrodes in the sulfuric acid, where the energy is stored by a proton-rocking-chair mechanism resulting from a quinone couple trapped inside the nanopores of ZTC with a less crystalline or nanocrystalline structure. The assembled device possesses an energy density as high as 30.6 Wh kg −1 , which is superior to the activated-carbon-based capacitors working in the organic electrolytes and lead batteries. [ABSTRACT FROM AUTHOR]

A novel and selective electrochemical functionalization of a highly reactive superporous zeolite templated carbon (ZTC) with two different aminobenzene acids (2-aminobenzoic and 4-aminobenzoic acid) was achieved. The functionalization was done through potentiodynamic treatment in acid media under oxidative conditions, which were optimized to preserve the unique ZTC structure. Interestingly, it was possible to avoid the electrochemical oxidation of the highly reactive ZTC structure by controlling the potential limit of the potentiodynamic experiment in presence of aminobenzene acids. The electrochemical characterization demonstrated the formation of polymer chains along with covalently bonded functionalities to the ZTC surface. The functionalized ZTCs showed several redox processes, producing a capacitance increase in both basic and acid media. The rate performance showed that the capacitance increase is retained at scan rates as high as 100 mV s −1 , indicating that there is a fast charge transfer between the polymer chains formed inside the ZTC porosity or the new surface functionalities and the ZTC itself. The success of the proposed approach was also confirmed by using other characterization techniques, which confirmed the presence of different nitrogen groups in the ZTC surface. This promising method could be used to achieve highly selective functionalization of highly porous carbon materials. [ABSTRACT FROM AUTHOR]

Abstract: The magnetic properties of host–guest systems composed of a nanoporous network of curved sp2-nanocarbon sheets are investigated by using zeolite-templated carbon (ZTC) as a host material with focus on the effects of aging after synthesis, the presence of the template, and guest adsorption. There are two kinds of localized magnetic moments originating from a radical state at a curved part and an edge state at an edge part of the individual nanocarbon sheet. The ZTC sample just after synthesis shows an antiferromagnetic transition at 13K, which disappears through aging process under ambient gas species such as oxygen. On the other hand, the template removing process during synthesis by using non-oxidizing reagent does not influence the magnetism of ZTC. The results of bromine adsorption reveal that a curved part responsible for the radical state in ZTC is destroyed through chemical reactions with the electron-accepting species. Potassium adsorbed into the nanopores in ZTC, forms magnetic clusters which undergo a ferromagnetic transition at 24K. The ZTC spins well decoupled with the potassium spins act as a probe in observing the magnetic behavior of the guest potassium. [Copyright &y& Elsevier]

Two zeolite templated carbons (ZTC) with comparable structure and different surface chemistry have been synthesized by chemical vapor deposition of different precursors, producing a non-doped and a N-doped carbon material (4 at. % XPS) in which most of the functionalities are quaternary N. A larger specific capacitance (farads per surface area) has been measured in acid electrolyte for the N-doped ZTC, that can be related to an improved wettability due to the presence of nitrogen and oxygen. The capacitance of N-doped ZTC is lower in alkaline electrolyte, probably due to the loss of electrochemical activity of certain oxygen functionalities. Interestingly, the electro-oxidation process of N-ZTC implies lower irreversible currents (providing higher electrochemical stability) than for ZTC. The presence of quaternary nitrogen greatly improves the electric conductivity of N-ZTC, which shows a superior rate performance. ZTC and N-ZTC capacitors were constructed using 1 M H 2 SO 4 . Under the same conditions, N-doped ZTC based capacitor has higher energy density, 6.7 vs 5.9 W h/kg. The power density of N-ZTC is four times higher, producing an outstanding maximum power of 98 kW/kg. These results provide clear evidences of the advantages of doping advanced porous carbon materials with nitrogen functionalities. [ABSTRACT FROM AUTHOR]

Highlights: [•] Confined water in zeolite-templated carbon (ZTC) was studied by XRD, DSC, NMR and MD. [•] Water of 140wt.% is adsorbed. It is highly mobile and liquid like down to 200K. [•] Crossover between low-density (LD) and high-density (HD) states is discussed. [•] The glass transition temperature to LD amorphous (LDA) is around 150K. [•] ZTC provides a new platform to study three-dimensional ‘supercooled’ water. [Copyright &y& Elsevier]

Abstract: Ordered microporous carbons synthesized by the template method using zeolite Y were hot-pressed at 573K up to 147MPa, aiming at densification of the templated carbons for the future use as energy storage media. Upon the hot-pressing, the powdery templated carbons were easily pelletized without any binder and the bulk density was significantly increased from 0.2g/cm3 to 0.7–0.9g/cm3. As a result, both the surface area and micropore volume per unit volume were increased. Surprisingly, it was found that the hot-pressing treatment reduced the average micropore size and it was tunable by simply adjusting a pressure in the treatment. In contrast, such changes in the density and the pore structure were not observed for commercial KOH-activated carbons when they were hot-pressed under the same conditions. The observed peculiar behavior of the templated carbons upon the hot-pressing can be explained by their unique molecular structure as compared to the conventional activated carbons. [Copyright &y& Elsevier]

Abstract: To settle the hydrogen adsorption sites on buckybowl C36H12, which is picked up from zeolite-templated carbon (ZTC), we have performed path integral molecular dynamics (PIMD) simulation including thermal and nuclear quantum fluctuations under semi-empirical PM3 method. In the static PM3 calculation and classical simulation the five stable adsorption sites of hydrogen atom are optimized inside a buckybowl C36H12, which are labeled as α-, β1-, β2-, γ-, and δ-carbons from edge to innermost carbon. In PIMD simulation, meanwhile, stable adsorption site is not appeared on δ-carbon, but on only α-, β1-, β2-, and γ-carbons. This result is due to the fact that the adsorbed hydrogen atom can easily go over the barrier for hydrogen transferring from δ- to β1-carbons by thermal and nuclear quantum fluctuations. The thermal and nuclear quantum effects are key role to settle the hydrogen adsorption sites on carbon materials. [Copyright &y& Elsevier]