Publications by authors named "Seong-Ho Yoon"

32 Publications

Highly Chlorinated Polyvinyl Chloride as a Novel Precursor for Fibrous Carbon Material.

Polymers (Basel) 2020 Feb 5;12(2). Epub 2020 Feb 5.

Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

Pure, highly chlorinated polyvinyl chloride (CPVC), with a 63 wt % of chlorine, showed a unique-thermal-pyrolytic-phenomenon that meant it could be converted to carbon material through solid-phase carbonisation rather than liquid-phase carbonisation. The CPVC began to decompose at 270 °C, with a rapid loss in mass due to dehydrochlorination and novel aromatisation and polycondensation up to 400 °C. In this study, we attempted to prepare carbon fibre (CF) without oxidative stabilisation, using the aforementioned CPVC as a novel precursor. Through the processes of solution spinning and solid-state carbonisation, the spun CPVC fibre was directly converted to CF, with a carbonisation yield of 26.2 wt %. The CPVC-derived CF exhibited a relatively smooth surface; however, it still demonstrated a low mechanical performance. This was because the spun fibre was not stretched during the heat treatment. Tensile strength, Young's modulus and elongation values of 590 ± 84 MPa, 50 ± 8 GPa, and 1.2 ± 0.2%, respectively, were obtained from the CPVC spun fibre, with an average diameter of 19.4 μm, following carbonisation at 1600 °C for 5 min.
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http://dx.doi.org/10.3390/polym12020328DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7077477PMC
February 2020

Evolution of Phosphorus-Containing Groups on Activated Carbons during Heat Treatment.

Langmuir 2017 03 17;33(12):3112-3122. Epub 2017 Mar 17.

Institute for Materials Chemistry and Engineering Sciences, Kyushu University , Fukuoka 8168580, Japan.

Two types of activated carbons have been prepared by HPO activation of lignocellulose and by HPO modification of activated carbon, and then heat-treated at temperatures from 400 to 900 °C in an atmosphere of N or H to investigate the evolution of phosphorus-containing groups. Elemental analysis, X-ray photoelectron spectroscopy, P nuclear magnetic resonance, nitrogen adsorption, and scanning electron microscopy have been used to analyze the physicochemical properties of the activated carbons. The results show that C-O-P linkages of phosphorus-containing groups can progressively evolve into C-P-O, C-P═O, C-P, and eventually elemental phosphorus as a result of heat treatment. Phosphate-like groups are much more thermally stable in an N than in an H atmosphere. In N, C-O-P linkages significantly evolve into C-P-O and C-P═O at up to 800 °C, whereas C-P linkages are not formed even at 900 °C. In H, the corresponding evolution remarkably occurs at 500 °C, forming C-P linkages and eventually elemental phosphorus. Moreover, the two activated carbons exhibit different evolution trends, suggesting that the evolution happens more easily for phosphorus-containing groups located on the edges of graphite-like crystallites than those in the lattice. Finally, we propose different evolution pathways of phosphorus-containing groups upon heat treatment in N and H atmospheres.
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http://dx.doi.org/10.1021/acs.langmuir.7b00095DOI Listing
March 2017

Fast Water Relaxation through One-Dimensional Channels by Rapid Energy Transfer.

Chemphyschem 2016 Nov 20;17(21):3409-3415. Epub 2016 Sep 20.

Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi Tsukuba, Ibaraki, 305-8565, Japan.

Water in carbon nanotubes is surrounded by hydrophobic carbon surfaces and shows anomalous structural and fast transport properties. However, the dynamics of water in hydrophobic nanospaces is only phenomenologically understood. In this study, water dynamics in hydrophobic carbon nanotubes is evaluated based on water relaxation using nuclear magnetic resonance spectroscopy and molecular dynamics simulations. Extremely fast relaxation (0.001 s) of water confined in carbon nanotubes of 1 nm in diameter on average is observed; the relaxation times of water confined in carbon nanotubes with an average diameter of 2 nm (0.40 s) is similar to that of bulk water (0.44 s). The extremely fast relaxation time of water confined in carbon nanotubes with an average diameter of 1 nm is a result of frequent energy transfer between water and carbon surfaces. Water relaxation in carbon nanotubes of average diameter 2 nm is slow because of the limited number of collisions between water molecules. The dynamics of interfacial water can therefore be controlled by varying the size of the hydrophobic nanospace.
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http://dx.doi.org/10.1002/cphc.201600895DOI Listing
November 2016

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells.

Nanomaterials (Basel) 2016 Aug 15;6(8). Epub 2016 Aug 15.

Fuel Cell Research Center, Korea Institute of Energy Research (KIER), Daejeon 305-343, Korea.

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF-supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.
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http://dx.doi.org/10.3390/nano6080148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5224627PMC
August 2016

Formation of single-layered Pt islands on Au(111) using irreversible adsorption of Pt and selective adsorption of CO to Pt.

Langmuir 2014 Apr 9;30(15):4203-6. Epub 2014 Apr 9.

Department of Chemistry, Chungnam National University , Daejeon 305-764, Korea.

This communication compares two different multiple deposition routes of Pt on Au(111), using irreversible adsorption of Pt precursor ions and selective adsorption of CO. A scanning tunneling microscopy study revealed that the conventional route, not utilizing CO, produced multiple-layered Pt cluster islands, while the CO route, employing CO, formed single-layered Pt islands exclusively. The role of CO selectively adsorbed on pre-existing Pt islands was to prevent additional irreversible adsorption of Pt precursor ions onto Pt islands. Cyclic voltammetric works disclosed that the CO and hydrogen coverages on single-layered Pt islands were higher than those on multiple-layered ones, and that the Pt islands on Au were more effective in adsorbing CO than hydrogen.
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http://dx.doi.org/10.1021/la500005pDOI Listing
April 2014

Chemicals from direct coal liquefaction.

Chem Rev 2014 Feb 26;114(3):1637-72. Epub 2013 Dec 26.

Research and Education Center of Carbon Resources, Kyushu University , 6-1 Kasuga Koen, Kasuga, Fukuoka 816-8580, Japan.

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http://dx.doi.org/10.1021/cr4002885DOI Listing
February 2014

Chemoselective hydrogenation of functionalized nitroarenes and imines by using carbon nanofiber-supported iridium nanoparticles.

Chem Asian J 2014 Jan 4;9(1):71-4. Epub 2013 Nov 4.

Toyota Technological Institute, Nagoya, Aichi 468-8511 (Japan), Fax: (+81) 52-809-1721.

The reaction of three types of carbon nanofibers (CNFs; platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) with Ir4(CO)12 in mesitylene at 165 °C provided the corresponding CNF-supported iridium nanoparticles, Ir/CNFs (Ir content=2.3-2.6 wt.%). Transmission electron microscopy (TEM) studies of these Ir/CNF samples revealed that size-controlled Ir nanoparticles (average particle size of 1.1-1.5 nm) existed on the CNFs. Among the three Ir/CNF samples, Ir/CNF-T showed an excellent catalytic activity and chemoselectivity towards hydrogenation of functionalized nitroarenes and imines; the corresponding aniline derivatives were obtained with high turnover numbers at ambient temperature under 10 tm of H2 , and the catalyst is reusable. Ir/CNF-T was also effective for the reductive N-alkylation of anilines with carbonyl compounds.
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http://dx.doi.org/10.1002/asia.201301184DOI Listing
January 2014

Hollow fibers networked with perovskite nanoparticles for H2 production from heavy oil.

Sci Rep 2013 Oct 9;3:2902. Epub 2013 Oct 9.

1] Department of Chemical and Biomolecular Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 120-749, Korea [2].

Design of catalytic materials has been highlighted to build ultraclean use of heavy oil including liquid-to-gas technology to directly convert heavy hydrocarbons into H2-rich gas fuels. If the H2 is produced from such heavy oil through high-active and durable catalysts in reforming process that is being constructed in hydrogen infrastructure, it will be addressed into renewable energy systems. Herein, the three different hollow fiber catalysts networked with perovskite nanoparticles, LaCr(0.8)Ru(0.2)O3, LaCr(0.8)Ru(0.1)Ni(0.1)O3, and LaCr(0.8)Ni(0.2)O3 were prepared by using activated carbon fiber as a sacrificial template for H2 production from heavy gas oil reforming. The most important findings were arrived at: (i) catalysts had hollow fibrous architectures with well-crystallized structures, (ii) hollow fibers had a high specific surface area with a particle size of ≈50 nm, and (iii) the Ru substituted ones showed high efficiency for H2 production with substantial durability under high concentrations of S, N, and aromatic compounds.
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http://dx.doi.org/10.1038/srep02902DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3793222PMC
October 2013

Toward an effective adsorbent for polar pollutants: formaldehyde adsorption by activated carbon.

J Hazard Mater 2013 Sep 7;260:82-8. Epub 2013 May 7.

Department of Fine Chemical Engineering and Applied Chemistry, College of Engineering, Chungnam National University, 99 Daehak-ro (st), Yuseong-gu, Daejeon 305-764, Republic of Korea.

Due to increasing concerns about environmental pollutants, the development of an effective adsorbent or sensitive sensor has been pursued in recent years. Diverse porous materials have been selected as promising candidates for detecting and removing harmful materials, but the most appropriate pore structure and surface functional groups, both important factors for effective adsorbency, have not yet been fully elucidated. In particular, there is limited information relating to the use of activated carbon materials for effective adsorbent of specific pollutants. Here, the pore structure and surface functionality of polyacrylonitrile-based activated carbon fibers were investigated to develop an efficient adsorbent for polar pollutants. The effect of pore structure and surface functional groups on removal capability was investigated. The activated carbons with higher nitrogen content show a great ability to absorb formaldehyde because of their increased affinity with polar pollutants. In particular, nitrogen functional groups that neighbor oxygen atoms play an important role in maximizing adsorption capability. However, because there is also a similar increase in water affinity in adsorbents with polar functional groups, there is a considerable decrease in adsorption ability under humid conditions because of preferential adsorption of water to adsorbents. Therefore, it can be concluded that pore structures, surface functional groups and the water affinity of any adsorbent should be considered together to develop an effective and practical adsorbent for polar pollutants. These studies can provide vital information for developing porous materials for efficient adsorbents, especially for polar pollutants.
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http://dx.doi.org/10.1016/j.jhazmat.2013.04.049DOI Listing
September 2013

Pt nanoparticle-reduced graphene oxide nanohybrid for proton exchange membrane fuel cells.

J Nanosci Nanotechnol 2012 Jul;12(7):5669-72

Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 120-749, South Korea.

A platinum nanoparticle-reduced graphene oxide (Pt-RGO) nanohybrid for proton exchange membrane fuel cell (PEMFC) application was successfully prepared. The Pt nanoparticles (Pt NPs) were deposited onto chemically converted graphene nanosheets via ethylene glycol (EG) reduction. According to the powder X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) analysis, the face-centered cubic Pt NPs (3-5 nm in diameter) were homogeneously dispersed on the RGO nanosheets. The electrochemically active surface area and PEMFC power density of the Pt-RGO nanohybrid were determined to be 33.26 m2/g and 480 mW/cm2 (maximum values), respectively, at 75 degrees C and at a relative humidity (RH) of 100% in a single-cell test experiment.
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http://dx.doi.org/10.1166/jnn.2012.6350DOI Listing
July 2012

Synthesis of silicon monoxide-pyrolytic carbon-carbon nanofiber composites and their hybridization with natural graphite as a means of improving the anodic performance of lithium-ion batteries.

Nanotechnology 2012 Sep 15;23(35):355601. Epub 2012 Aug 15.

Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, Japan.

Novel composites of silicon monoxide, pyrolytic carbon and carbon nanofiber (SiO/PyC/CNF) were hybridized with natural graphite (NG) as a means of improving the anodic performance of Li-ion batteries. Samples were made with hybridization levels of 10-30 wt% of NG exhibited excellent cyclability with a discharge capacity of 389-522 mAh g(-1) in a Li-ion battery system. SiO/PyC/CNF composite hybrids showed better cyclability than other carbon composites containing SiO/PyC and SiO/CNF. These hybridization effects were attributed to the lower contact resistance of SiO/PyC/CNF in the electrode. The internal spaces created throughout the SiO/PyC/CNF composite and their effect on material dispersion in the hybridized electrodes may have prevented electrode damage by relieving tensions induced by the expansion of SiO particles in the electrode over the course of repeated charge and discharge processes.
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http://dx.doi.org/10.1088/0957-4484/23/35/355601DOI Listing
September 2012

Structure and electrochemical applications of boron-doped graphitized carbon nanofibers.

Nanotechnology 2012 Aug 13;23(31):315602. Epub 2012 Jul 13.

Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d₀₀₂) of the boron-doped graphitized CNFs reached 3.356 Å, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d₀₀₂ is less than 3.400 Å, were selected for further heat treatment. The first heat treatment of PCNFs at 2800 °C yielded a d₀₀₂ between 3.357 and 3.365 Å. Successive nitric acid treatment and a second heat treatment with boric acid reduced d₀₀₂ to 3.356 Å. The resulting boron-doped PCNFs exhibited a high discharge capacity of 338 mAh g⁻¹ between 0 and 0.5 V versus Li/Li⁺ and 368 mAh g⁻¹ between 0 and 1.5 V versus Li/Li⁺. The first-cycle Coulombic efficiency was also enhanced to 71-80%. Such capacity is comparable to that of natural graphite under the same charge/discharge conditions. The boron-doped PCNFs also exhibited improved rate performance with twice the capacity of boron-doped natural graphite at a discharge rate of 5 C.
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http://dx.doi.org/10.1088/0957-4484/23/31/315602DOI Listing
August 2012

High magnetic field solid-state NMR analyses by combining MAS, MQ-MAS, homo-nuclear and hetero-nuclear correlation experiments.

Magn Reson Chem 2012 Apr 6;50(4):289-94. Epub 2012 Mar 6.

Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka, 816-8580, Japan.

A general strategy of structural analysis of alumina silicate by combining various solid-state NMR measurements such as single pulse, multi-quantum magic angle spinning, double-quantum homo-nuclear correlation under magic angle spinning (DQ-MAS), and cross-polarization hetero-nuclear correlation (CP-HETCOR) was evaluated with the aid of high magnetic field NMR (800 MHz for (1) H Larmor frequency) by using anorthite as a model material. The high magnetic field greatly enhanced resolution of (27) Al in single pulse, DQ-MAS, and even in triple-quantum magic angle spinning NMR spectra. The spatial proximities through dipolar couplings were probed by the DQ-MAS methods for homo-nuclear correlations between both (27) Al-(27) Al and (29) Si-(29) Si and by CP-HETCOR for hetero-nuclear correlations between (27) Al-(29) Si in the anorthite framework. By combining various NMR methodologies, we elucidated detailed spatial correlations among various aluminum and silicon species in anorthite that was hard to be determined using conventional analytical methods at low magnetic field. Moreover, the presented approach is applicable to analyze other alumina-silicate minerals.
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http://dx.doi.org/10.1002/mrc.3804DOI Listing
April 2012

Electrochemical catalytic activity for oxygen reduction reaction of nitrogen-doped carbon nanofibers.

J Nanosci Nanotechnol 2011 Jul;11(7):6350-8

Advanced Energy Technology, University of Science and Technology (UST), Daejeon 305-333, Republic of Korea.

The electrocatalytic activity of nitrogen-doped carbon nanofibers (N-CNFs), which are synthesized directly from vaporized acetonitrile over nickel-iron based catalysts, for oxygen reduction reaction (ORR), was investigated. The nitrogen content and specific surface area of N-CNFs can be controlled through the synthesis temperature (300-680 degrees C). The graphitization degree of N-CNFs also are significantly affected by the temperature, whereas the chemical compositions of nitrogen species are similar irrespective of the synthesis conditions. From measurement of the electrochemical double layer capacitance, the surface of N-CNFs is found to have stronger interaction with ions than undoped-carbon surfaces. Although N-CNFs show higher over-potential than Pt catalysts do, N-CNFs were observed to have a noticeable ORR activity, as opposed to the carbon samples without nitrogen doping. The activity dependency of N-CNFs on the content of the nitrogen with which they were doped is discussed, based on the experiment results. The single cell of the direct methanol fuel cell (DMFC) was tested to investigate the performance of a membrane-electrode assembly that includes N-CNFs as the cathode catalyst layer.
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http://dx.doi.org/10.1166/jnn.2011.4443DOI Listing
July 2011

IVS6+5G>A found in Wiskott-Aldrich syndrome and X-linked thrombocytopenia in a Korean family.

Pediatr Blood Cancer 2012 Feb 28;58(2):297-9. Epub 2011 Oct 28.

Department of Pediatrics, Hanyang University Medical Center, Seoul, Korea.

Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) are caused by a mutation in the WAS gene on Xp11.22. We report two patients with IVS6+5G>A of WAS in a Korean family. The proband presented with classic WAS, whereas his maternal cousin had symptoms limited to XLT. Their mothers were proved to be carriers. The IVS6+5G>A mutation was reported to result in incomplete splicing of the donor site and typically associated with mild form of disease, XLT. Our observation of the intrafamilial variability of clinical manifestations of WAS further expands the genotype-phenotype correlations and suggests the presence of modifying genetic factors.
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http://dx.doi.org/10.1002/pbc.23377DOI Listing
February 2012

Graphitization behaviour of chemically derived graphene sheets.

Nanoscale 2011 Sep 1;3(9):3652-6. Epub 2011 Aug 1.

State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, China.

Graphene sheets were prepared via chemical reduction of graphite oxides and then graphitized at 2800 °C. The structure changes from pristine graphite to graphitized graphene sheets were monitored using X-ray diffraction and Raman spectroscopy. It was found that the graphitized graphene sheets exhibited relatively low degree of graphitization and high level of structural defects. XPS spectra revealed that oxygen functionalities could be completely eliminated after graphitization. Morphology observations indicated that graphitization could induce the coalescence and connection of the crumpled graphene agglomerations into compressed grains. The connections included the joint of graphitic sheets along the c-axis with van der Waals force between graphitic sheets and the joint of sheets in the in-plane with covalent bond between carbon atoms. New structures such as the formation of loop at the tip of graphene sheets and the formation of 3D concentric graphene nanoparticles occurred in the graphitized graphene sheets, as a result of self-organization to achieve their lowest potential energy. Our findings should provide some experimental implications for understanding of graphitization behaviour and thermal stability of strictly 2D graphene monolayers.
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http://dx.doi.org/10.1039/c1nr10409hDOI Listing
September 2011

Partially unzipped carbon nanotubes as a superior catalyst support for PEM fuel cells.

Chem Commun (Camb) 2011 Sep 20;47(33):9429-31. Epub 2011 Jul 20.

State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, China.

Partially unzipped carbon nanotubes prepared by strong oxidation and thermal expansion of carbon nanotubes were explored as an advanced catalyst support for PEM fuel cells. The unique hybrid structure of 1D nanotube and 2D double-side graphene resulted in an outstanding electrocatalytic performance.
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http://dx.doi.org/10.1039/c1cc13488dDOI Listing
September 2011

Fabrication of uniform graphene discs via transversal cutting of carbon nanofibers.

ACS Nano 2011 Aug 20;5(8):6254-61. Epub 2011 Jul 20.

Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

The graphene discs with well-defined shape are successfully fabricated using a simple oxidation and exfoliation process of high-crystalline carbon nanofibers (CNFs). To control the shapes of graphene discs, two different types of CNFs (platelet and herringbone-type) are used as starting materials. The CNFs are formed by the perpendicular stacking of graphene discs, resulting in free edges on the external surface and ready access to interlay spaces. Interestingly, the diameter and shape of the graphene discs can be controlled by selectively designing the morphology of starting materials and optimizing the cutting method. In addition, a mechanical reduction method for oxidized graphene discs is also proposed in order to combine the high recovery of π-conjugated electronic structure with the solution processability of graphene discs. The reduced graphene discs can be formed without any additives, such as reducing agent, and are highly dispersed in different solvents with a high content of graphene discs. This novel strategy offers great possibility for fabricating various graphene-based nanomaterials with rational nanostructure design.
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http://dx.doi.org/10.1021/nn201195gDOI Listing
August 2011

Structural units and their periodicity in carbon nanotubes.

Small 2010 Nov;6(22):2526-9

Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

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http://dx.doi.org/10.1002/smll.201001263DOI Listing
November 2010

Preparation of nitrogen-doped graphene sheets by a combined chemical and hydrothermal reduction of graphene oxide.

Langmuir 2010 Oct;26(20):16096-102

Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

Nitrogen-doped graphene sheets were prepared through a hydrothermal reduction of colloidal dispersions of graphite oxide in the presence of hydrazine and ammonia at pH of 10. The effect of hydrothermal temperature on the structure, morphology, and surface chemistry of as-prepared graphene sheets were investigated though XRD, N(2) adsorption, solid-state (13)C NMR, SEM, TEM, and XPS characterizations. Oxygen reduction and nitrogen doping were achieved simultaneously under the hydrothermal reaction. Up to 5% nitrogen-doped graphene sheets with slightly wrinkled and folded feature were obtained at the relative low hydrothermal temperature. With the increase of hydrothermal temperature, the nitrogen content decreased slightly and more pyridinic N incorporated into the graphene network. Meanwhile, a jellyfish-like graphene structure was formed by self-organization of graphene sheets at the hydrothermal temperature of 160 °C. Further increase of the temperature to 200 °C, graphene sheets could self-aggregate into agglomerate particles but still contained doping level of 4 wt % N. The unique hydrothermal environment should play an important role in the nitrogen doping and the jellyfish-like graphene formation. This simple hydrothermal method could provide the synthesis of nitrogen-doped graphene sheets in large scale for various practical applications.
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http://dx.doi.org/10.1021/la102425aDOI Listing
October 2010

Rhodium nanoparticles supported on carbon nanofibers as an arene hydrogenation catalyst highly tolerant to a coexisting epoxido group.

Org Lett 2009 Nov;11(21):5042-5

Institute for Materials Chemistry and Engineering, Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

Rhodium nanoparticles supported on a carbon nanofiber (Rh/CNF-T) show high catalytic activity toward arene hydrogenation under mild conditions in high turnover numbers without leaching the Rh species; the reaction is highly tolerant to epoxido groups, which often undergo ring-opening hydrogenation with conventional catalysts.
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http://dx.doi.org/10.1021/ol902018gDOI Listing
November 2009

Direct synthesis and structural analysis of nitrogen-doped carbon nanofibers.

Langmuir 2009 Jul;25(14):8268-73

Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 816-8580, Japan.

Carbon nanofibers containing a range of nitrogen contents of 1-10 atom % were directly synthesized by catalytic chemical vapor deposition over nickel-based catalysts at 350-600 degrees C using acetonitrile and acrylonitrile. The nitrogen content was controlled by careful choice of the reaction conditions. The N-doped carbon nanofibers showed herringbone structure with 20-60 nm diameter. X-ray photoelectron spectroscopy was applied to examine the chemical state of nitrogen in carbon nanofibers. Structural features of N-doped carbon nanofibers were examined in X-ray diffraction and electron microscopy. The mechanism for nitrogen including the structure of carbon nanofibers through the catalysis was discussed on the basis of the results.
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http://dx.doi.org/10.1021/la900472dDOI Listing
July 2009

Pore structure analysis of activated carbon fiber by microdomain-based model.

Langmuir 2009 Jul;25(13):7631-7

Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

The pore structures of commercial pitch and PAN-based activated carbon fibers (ACFs) were investigated. The pore size and pore size distribution of pitch-based ACFs were measured by nitrogen adsorption isotherms and 129Xe NMR spectroscopy and compared with each other. Scanning tunneling microscopy showed that the ACFs were composed of spherical microdomain units the size of a few nanometers. The activation mechanism of ACFs was considered and explained by novel hypothesis; the concept of microdomain structure of ACFs was considered and explained to overcome limitation of the conventional fractal hypothesis. Whereas micropores were generated on each microdomain, the origin of mesopores was interdomain pores, resulting from the microdomain hypothesis.
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http://dx.doi.org/10.1021/la9000347DOI Listing
July 2009

Chemoselective hydrogenation of nitroarenes with carbon nanofiber-supported platinum and palladium nanoparticles.

Org Lett 2008 Apr 14;10(8):1601-4. Epub 2008 Mar 14.

Graduate School of Engineering Sciences, Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka, Japan.

Platinum and palladium nanoparticles supported on three types of carbon nanofibers (CNFs) are synthesized and used as catalysts in the hydrogenation of nitroarenes. Nanosized platinum particles dispersed on platelet-type CNF efficiently catalyze the reduction of functionalized nitroarenes to the corresponding substituted anilines in high turnover numbers with other functional groups remaining intact.
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http://dx.doi.org/10.1021/ol800277aDOI Listing
April 2008

Highly efficient synthesis of optically pure 5,5',6,6',7,7',8,8'-octahydro-1,1'-bi-2-naphthol and -naphthylamine derivatives by partial hydrogenation of 1,1'-binaphthyls with carbon nanofiber supported ruthenium nanoparticles.

J Org Chem 2007 Dec 29;72(26):10291-3. Epub 2007 Nov 29.

Graduate School of Engineering Sciences, Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

Use of Ru/CNF-P, nanoruthenium particles dispersed on a nanocarbon fiber support, realizes highly efficient catalytic partial hydrogenation of 1,1'-bi-2-naphthol and -naphthyl-amine derivatives. The reactions proceed in high turnover numbers without racemization of the axial chirality, offering a practical procedure for the production of optically pure 5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyls in good to high yields.
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http://dx.doi.org/10.1021/jo702015jDOI Listing
December 2007

Ruthenium nanoparticles on nano-level-controlled carbon supports as highly effective catalysts for arene hydrogenation.

Chem Asian J 2007 Dec;2(12):1524-33

Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

The reaction of three types of carbon nanofibers (CNFs; platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) with [Ru3(CO)12] in toluene heated at reflux provided the corresponding CNF-supported ruthenium nanoparticles, Ru/CNFs (Ru content = 1.1-3.8 wt %). TEM studies of these Ru/CNFs revealed that size-controlled Ru nanoparticles (2-4 nm) exist on the CNFs, and that their location was dependent on the surface nanostructures of the CNFs: on the edge of the graphite layers (CNF-P), in the tubes and on the surface (CNF-T), and between the layers and on the edge (CNF-H). Among these Ru/CNFs, Ru/CNF-P showed excellent catalytic activity towards hydrogenation of toluene with high reproducibility; the reaction proceeded without leaching of the Ru species, and the catalyst was reusable. The total turnover number of the five recycling experiments for toluene hydrogenation reached over 180,000 (mol toluene) (mol Ru)(-1). Ru/CNF-P was also effective for the hydrogenation of functionalized benzene derivatives and pyridine. Hydrogenolysis of benzylic C-O and C-N bonds has not yet been observed. Use of poly(ethylene glycol)s (PEGs) as a solvent made possible the biphasic catalytic hydrogenation of toluene. After the reaction, the methylcyclohexane formed was separated by decantation without contamination of the ruthenium species and PEG. The insoluble PEG phase containing all of the Ru/CNF was recoverable and reusable as the catalyst without loss of activity.
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http://dx.doi.org/10.1002/asia.200700175DOI Listing
December 2007

Carbon nanofibers: a novel nanofiller for nanofluid applications.

Small 2007 Jul;3(7):1209-13

Hyperstructured Organic Materials Research Center and School of Chemical Engineering, Seoul National University, Shinlimdong 56-1, Seoul 151-742, Korea.

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http://dx.doi.org/10.1002/smll.200700066DOI Listing
July 2007

Fast preparation of PtRu catalysts supported on carbon nanofibers by the microwave-polyol method and their application to fuel cells.

Langmuir 2007 Jan;23(2):387-90

Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8580, Japan.

PtRu alloy nanoparticles (24 +/- 1 wt %, Ru/Pt atomic ratios = 0.91-0.97) supported on carbon nanofibers (CNFs) were prepared within a few minutes by using a microwave-polyol method. Three types of CNFs with very different surface structures, such as platelet, herringbone, and tubular ones, were used as new carbon supports. The dependence of particles sizes and electrochemical properties on the structures of CNFs was examined. It was found that the methanol fuel cell activities of PtRu/CNF catalysts were in the order of platelet > tubular > herringbone. The methanol fuel cell activities of PtRu/CNFs measured at 60 degrees C were 1.7-3.0 times higher than that of a standard PtRu (29 wt %, Ru/Pt atomic ratio = 0.92) catalyst loaded on carbon black (Vulcan XC72R) support. The best electrocatalytic activity was obtained for the platelet CNF, which is characterized by its edge surface and high graphitization degree.
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http://dx.doi.org/10.1021/la062223uDOI Listing
January 2007

Electrochemical capacitances of well-defined carbon surfaces.

Langmuir 2006 Oct;22(22):9086-8

Department of Chemistry, Chungnam National University, Daejeon, 305-764, South Korea.

Reported is the capacitive behavior of homogeneous and well-defined surfaces of pristine carbon nanofibers (CNFs) and surface-modified CNFs. The capacitances of the well-defined CNFs were measured with cyclic voltammetry to correlate the surface structure with capacitance. Among the studied pristine CNFs, the edge surfaces of platelet CNFs (PCNF) and herringbone CNFs were more effective in capacitive charging than the basal plane surface of tubular CNF by a factor of 3-5. Graphitization of PCNF (GPCNF) changed the edge surface of PCNF into a domelike basal plane surface, and the corresponding capacitances decreased from 12.5 to 3.2 F/g. A chemical oxidation of the GPCNF, however, recovered a clear edge surface by removal of the curved basal planes to increase the capacitance to 5.6 F/g. The difference in the contribution of the edge surface and basal-plane surface to the capacitance of CNF was discussed in terms of the anisotropic conductivity of graphitic materials.
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http://dx.doi.org/10.1021/la061380qDOI Listing
October 2006

A simple and easy home-based pulmonary rehabilitation programme for patients with chronic lung diseases.

Monaldi Arch Chest Dis 2005 Mar;63(1):30-6

Division of Pulmonary and Critical Medicine, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Korea.

Background And Aim: To develop a simple and easy home-based pulmonary rehabilitation programme and investigate its effectiveness.

Methods: Patients with stable chronic lung disease were divided into a rehabilitation group (n = 25) and a control group (n = 18). Rehabilitation consisted of education and 12 weeks of enforced aerobic and muscle-strengthening exercises. Aerobic exercise training was performed mostly by walking based on the functional capacity of the patients assessed by the maximal incremental exercise test. Patients visited hospital every two weeks for evaluation and a new exercise regimen.

Results: Five patients dropped out of the rehabilitation group but three were due to development of unrelated diseases, five controls did not co-operate in the second evaluation. After 12 weeks of rehabilitation, exercise capacity (maximum work load and VO2max), exercise endurance, 6-minute walking distance, and quality of life measured by the St. George Respiratory Questionnaire had significantly improved in the rehabilitation group but not in the controls. At a follow-up evaluation one year after the rehabilitation, some exercise parameters were still significantly higher than baseline in the rehabilitation group.

Conclusions: We developed a simple home-based pulmonary rehabilitation programme, which seems to be clinically feasible and effective.
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http://dx.doi.org/10.4081/monaldi.2005.655DOI Listing
March 2005
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