論文 - 松根 英樹
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Synthesis of hollow nanospheres consisting of amphiphilic block copolymers 査読あり
Matsune H., Sakurai D., Takenaka S., Kishida M.
Chemistry Letters 38 ( 7 ) 746 - 747 2009年7月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Chemistry Letters
Hollow polymeric nanospheres with shells consisting of inner hydrophilic and outer hydrophobic polymer chains are prepared by a surface-initiated living radical polymerization of 2-trimethylsilyloxyethyl acrylate and methyl methacrylate from initiator-modified silica nanoparticles; these nanospheres are subsequently prepared by intraparticle cross-linking and by dissolution of silica matrices with HF. The translation behavior of hydrophilic substrates from an aqueous phase to an oil phase through the nanocapsules is investigated. Copyright © 2009 The Chemical Society of Japan.
DOI： 10.1246/cl.2009.746
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Takenaka S., Matsumori H., Arike T., Matsune H., Kishida M.
Topics in Catalysis 52 ( 6-7 ) 731 - 738 2009年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Topics in Catalysis
Carbon nanotube (CNT)-supported Pt metal nanoparticles were covered with silica layers by hydrolysis of 3-aminopropyl-triethoxysilane (APTES) and/or tetraethoxysilane (TEOS). The hydrolysis of only APTES resulted in a uniform coverage of silica layers on Pt/CNT, but the thickness of the silica layers was very thin (<1 nm). Pt/CNT could also be coated with silica layers of a few nanometers in thickness by hydrolysis of TEOS, but exposed surfaces of CNTs in the sample were frequently observed. In contrast, the successive hydrolysis of APTES and TEOS brought about a uniform coverage of silica layers of a few nanometers in thickness on Pt/CNT. The silica-coated Pt/CNT showed high catalytic activity for electrochemical reactions in aqueous H2SO 4 electrolyte, in spite of a uniform coverage of Pt metal with silica layers. In addition, the coverage of Pt/CNT with silica layers improved its durability in electrochemical reactions. © Springer Science+Business Media, LLC 2009.
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Production of carbon nanotube by ethylene decomposition over silica-coated metal catalysts 査読あり
Iguchi T., Takenaka S., Nakagawa K., Orita Y., Matsune H., Kishida M.
Topics in Catalysis 52 ( 6-7 ) 563 - 570 2009年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Topics in Catalysis
Formation of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) through the decomposition of ethylene at 973 K was achieved using various metal catalysts covered with silica layers. CNFs of various diameters were formed by ethylene decomposition over a Co metal catalyst supported on the outer surface of the silica. In contrast, silica-coated Co catalysts formed CNTs with uniform diameters by ethylene decomposition. Silicacoated Ni/SiO2 and Pt/carbon black also formed CNTs with uniform diameters, while CNFs and CNTs with various diameters were formed over Ni/SiO2 and Pt/carbon black without a silica coating. These results indicate that silica layers that envelop metal particles prevent sintering of the metal particles during ethylene decomposition. This results in the preferential formation of CNTs with a uniform diameter. © Springer Science+Business Media, LLC 2009.
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Takenaka S., Iguchi T., Tanabe E., Matsune H., Kishida M.
Carbon 47 ( 5 ) 1251 - 1257 2009年4月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Carbon
Ethylene decomposition was performed over supported Pt catalysts to fabricate composites of Pt metal nanoparticles and carbon nanotubes (CNTs). All supported Pt catalysts (Pt/carbon black, Pt/CNT, Pt/MgO, Pt/Al2O3 and Pt/SiO2) showed catalytic activity for ethylene decomposition at 973 K to form CNTs. Pt metal particles were found at tips of CNTs. These results indicate that Pt metal particles have catalytic activity for growth of CNTs through hydrocarbon decomposition. A broad range (5-50 nm) of CNT diameters were formed from the use of supported Pt metal catalysts although Pt metal particles in the catalysts before ethylene decomposition were relatively uniform in size (2-5 nm). These results imply that Pt metal particles in the catalysts aggregated during ethylene decomposition at 973 K. Aggregation of Pt metal particles in catalysts during ethylene decomposition could be suppressed by covering catalysts with silica layers that were a few nanometers thick. Silica-coated Pt catalysts showed high activity for ethylene decomposition to form CNTs with uniform diameters (8-10 nm) despite the uniform coverage of Pt metal particles with silica layers. © 2009 Elsevier Ltd. All rights reserved.
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High resistance to carbon deposition of silica-coated Ni catalysts in propane stream reforming 査読あり
Takenaka S., Orita Y., Umebayashi H., Matsune H., Kishida M.
Applied Catalysis A: General 351 ( 2 ) 189 - 194 2008年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Applied Catalysis A: General
The catalytic performance of Ni metal catalysts uniformly covered with layers of silica for propane steam reforming was compared with the performances of Ni metal catalysts supported on substrates of magnesia (MgO), alumina (Al2O3) and silica (SiO2). The silica-coated Ni catalysts showed high activity for propane steam reforming at 873 K. This catalytic activity is higher than the activity of effective light alkane steam reforming Ni/Al2O3 and Ni/MgO catalysts and we found that the catalytic activity of the silica-supported Ni metal was poor. The coverage of Ni metal particles with silica thus improves their catalytic activity for this reaction. Carbon deposition on silica-coated Ni catalysts during the steam reforming of propane at 873 K was lower than that on Ni/MgO and Ni/Al2O3. Ni K-edge XANES and EXAFS spectra of silica-coated Ni catalyst showed a strong interaction between Ni metal and silica. This interaction prevents the sintering of Ni metal particles during the propane steam reforming, which results in the reduction of carbon deposition on silica-coated Ni catalysts. These properties of silica-coated Ni catalysts result in high catalytic activity and improved catalyst stability. © 2008 Elsevier B.V. All rights reserved.
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Takenaka S., Iguchi T., Tanabe E., Matsune H., Kishida M.
Chemistry Letters 37 ( 9 ) 944 - 945 2008年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Chemistry Letters
Pt metal particles supported on carriers such as MgO and SiO2 showed high activity for the formation of carbon nanotubes (CNTs) through ethylene decomposition at 973 K. However, these CNTs were not uniform in diameter because of the sintering of Pt metal particles during the reaction. Covering Pt catalysts with silica prevented the sintering of Pt metal particles during ethylene decomposition, resulting in the formation of CNTs with a uniform diameter. Copyright © 2008 The Chemical Society of Japan.
DOI： 10.1246/cl.2008.944
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Takenaka S., Matsumori H., Matsune H., Tanabe E., Kishida M.
Journal of the Electrochemical Society 155 ( 9 ) 2008年8月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of the Electrochemical Society
Multiwalled carbon nanotube (CNT)-supported Pt nanoparticles (Pt/CNT) were covered with silica layers by successive hydrolysis of 3-aminopropyl- triethoxysilane and tetraethoxysilane on CNTs with Pt metal precursors, followed by reduction with hydrogen. The Pt/CNT covered with silica layers (SiO 2/Pt/CNT) was used as a cathode catalyst for a proton exchange membrane fuel cell (PEMFC). The activity of SiO2/Pt/CNT catalyst for the oxygen reduction reaction in a single-cell PEMFC was similar to that of Pt/CNT, in spite of the uniform coverage of Pt with silica layers, indicating that the coverage of Pt/CNT with silica layers did not appreciably decrease the catalytic activity. In addition, SiO2/Pt/CNT electrocatalyst showed high stability during potential cycling from 0.05 to 1.20 V vs reversible hydrogen electrode in an aqueous H2SO4 electrolyte, whereas Pt/CNT significantly deactivated during the experiment. The structural change of Pt species in these electrocatalysts during potential cycling was investigated by transmission electron microscopy images and Pt L III-edge X-ray absorption fine structure. The crystallite size of Pt metal in SiO2/Pt/CNT did not change appreciably during the potential cycling, while Pt metal crystallites in Pt/CNT seriously aggregated. Silica layers enveloping Pt metal particles in SiO2/Pt/CNT prevent the dissolution and redeposition of Pt metal particles as well as the agglomeration of Pt metal particles on the supports. © 2008 The Electrochemical Society.
DOI： 10.1149/1.2952665
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Preparation of carbon nanotube-supported metal nanoparticles coated with silica layers 査読あり
Takenaka S., Arike T., Matsune H., Tanabe E., Kishida M.
Journal of Catalysis 257 ( 2 ) 345 - 355 2008年7月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Catalysis
Carbon nanotube (CNT)-supported Pt metal (Pt/CNT) was covered with silica layers using hydrolysis of 3-aminopropyl-triethoxysilane (APTES) and/or tetraethoxysilane (TEOS). The hydrolysis of APTES resulted in a uniform coverage of Pt/CNT with silica layers, but the silica layers were very thin. Pt/CNT could be coated with silica layers of a few nanometers thickness by hydrolysis of TEOS, but the thickness was not uniform. In contrast, the successive hydrolysis of APTES and TEOS resulted in a uniform coverage of Pt/CNT with silica layers of a few nanometers thickness. Pt metal particles in silica-coated Pt/CNT adsorbed CO chemically despite uniform coverage of Pt metal particles with silica layers. Therefore, silica-coated Pt/CNT demonstrated high catalytic activity in methane combustion. © 2008 Elsevier Inc. All rights reserved.
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Asahi T., Matsune H., Yamashita K., Masuhara H., Kasai H., Nakanishi H.
Polish Journal of Chemistry 82 ( 4 ) 687 - 699 2008年4月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Polish Journal of Chemistry
Single particle fluorescence spectroscopy coupled with AFM observation is reported for perylene nanocrystals. Fluorescence spectral measurement for individual nanocrystals with the size from 100 nm to 500 nm and fluorescence anisotropy analysis demonstrate that the size dependence in fluorescence is in the intrinsic nature of nanometer-sized crystal of perylene. Single nanoparticle fluorescence shows the enhanced monomer (M-) emission compared to the bulk crystal and a blue-shift of excimer (E-) emission peak wavelength by decreasing the nanoparticle size. It is found for the first time that the size dependence is correlated well to the surface-to-volume ratio of nanocrystal. The size-dependent fluorescence is not attributed to a quantum confinement effect of exciton, but to a change in the elastic properties of nanocrystal with size, which in turn affects excimer formation. We discuss the decrease in elastic constant of crystalline lattice due to large surface-to-volume ratio, and propose an empirical formula on the size-dependence of E-emission peak in the framework of the strong coupling model of exciton-phonon interaction.
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Matsune H., Sakurai D., Niidome Y., Takenaka S., Kishida M.
Journal of Bioscience and Bioengineering 105 ( 1 ) 58 - 60 2008年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Bioscience and Bioengineering
The degree of dynamic morphological change of murine embryonic stem cells is investigated through direct observation by microscopy. As a result, we find that the degree of dynamic morphological change is proportional to the increase in the ratio of the cellular population in subculture. © 2008 The Society for Biotechnology, Japan.
DOI： 10.1263/jbb.105.58
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Improvement in the durability of Pt electrocatalysts by coverage with silica layers 査読あり
Takenaka S., Matsumori H., Nakagawa K., Matsune H., Tanabe E., Kishida M.
Journal of Physical Chemistry C 111 ( 42 ) 15133 - 15136 2007年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Physical Chemistry C
Carbon nanotube (CNT)-supported Pt metal nanoparticles were covered with silica layers by utilizing the successive hydrolysis of 3-aminopropyl- triethoxysilane and tetraethoxysilane on CNTs with Pt hydroxide. The CNT-supported Pt metal particles covered with silica layers (denoted as SiO 2/Pt/CNT) were used as the electrocatalysts. SiO2/Pt/CNT electrocatalysts showed a high stability for the repeated potential cycling experiment, whereas Pt/CNT electrocatalysts were deactivated seriously for the experiment because of the growth of Pt metal particles in size. The silica layers in SiO2/Pt/CNT prevent the dissolution of Pt metal particles as well as the migration and agglomeration of Pt metal particles on the supports, which results in the improvement of the stability of Pt/CNT electrocatalysts. © 2007 American Chemical Society.
DOI： 10.1021/jp076120b
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Takenaka S., Orita Y., Arike T., Matsune H., Tanabe E., Kishida M.
Chemistry Letters 36 ( 10 ) 1250 - 1251 2007年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Chemistry Letters
Silica-coated Pt-based alloys (Pt-Co and Pt-Pd alloys) were prepared using a water-in-oil-type microemulsion. The silica-coated Pt-based alloys decomposed ethylene to form composites composed of the catalysts and carbon nanotubes. Copyright © 2007 The Chemical Society of Japan.
DOI： 10.1246/cl.2007.1250
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Takenaka S., Orita Y., Matsune H., Tanabe E., Kishida M.
Journal of Physical Chemistry C 111 ( 21 ) 7748 - 7756 2007年5月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Physical Chemistry C
Silica-supported Co catalysts were prepared by using microemulsion. The structure and state of the Co species in the catalysts were characterized by TEM, XRD, Co K-edge XANES/EXAFS, and diffuse reflectance UV-vis spectroscopy. Co species in the catalysts prepared using microemulsion were atomically dispersed as Co2+ with tetrahedral symmetry (CoO4), even after reduction of the catalysts with hydrogen at 773 K, while Co metal particles were supported on the silica surface for the catalysts prepared by a conventional impregnation method. The Co catalysts prepared using microemulsion selectively formed multi-walled carbon nanotubes with a uniform diameter by the decomposition of ethylene at 973 K, whereas silica-supported Co catalysts prepared by the impregnation method formed carbon nanofibers with various diameters. In addition, the Co catalysts prepared using microemulsion formed bundles of single- or double-walled carbon nanotubes by methane decomposition at 1073 K. Contact of the Co catalysts with hydrocarbons at the reaction temperatures (973 or 1073 K) resulted in the reduction of atomically dispersed Co oxide species to form small Co metal particles, which grew carbon nanotubes through hydrocarbon decomposition. © 2007 American Chemical Society.
DOI： 10.1021/jp070826o
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Production of CO-free hydrogen through the decomposition of LPG and kerosene over Ni-based catalysts 査読あり
Takenaka S., Kawashima K., Matsune H., Kishida M.
Applied Catalysis A: General 321 ( 2 ) 165 - 174 2007年4月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Applied Catalysis A: General
The catalytic performance of Ni-based catalysts for the decomposition of hydrocarbons of C3-C8 into CO-free hydrogen and carbon fibers was investigated in order to produce CO-free hydrogen as a fuel for PEFC from liquefied petroleum gas (LPG) and kerosene. The addition of Cu or Pd into Ni/SiO2 catalyst elongated its catalytic life for the propane decomposition. Especially, Ni-Pd/SiO2 catalyst showed higher activity and longer life for the decomposition of propane at 823 and 873 K, compared to Ni/SiO2 and Ni-Cu/SiO2 catalysts. Ni-Pd/SiO2 catalyst was deactivated gradually with time on stream during the decomposition of propane due to the deposition of large amounts of carbon. However, the activity of the catalyst for the propane decomposition was recovered completely by the gasification of deposited carbon with CO2 into CO. This result suggested that CO-free hydrogen and CO could be produced successively through the decomposition of hydrocarbons and the subsequent gasification of deposited carbon with CO2. Ni-Pd/SiO2 showed high catalytic activity for the decomposition of hydrocarbons of C6-C8 to form CO-free hydrogen. Thus, CO-free hydrogen was produced through the decomposition of commercial kerosene over Ni-Pd/SiO2 catalyst. © 2007 Elsevier B.V. All rights reserved.
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Nakagawa K., Takenaka S., Imagawa S., Matsune H., Kishida M.
Chemistry Letters 36 ( 2 ) 252 - 253 2007年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Chemistry Letters
Carbon nanofibers with uniform diameter of 10-15 nm were produced by the decomposition of ethylene over silica-supported Ni catalysts covered with silica layers. Copyright © 2007 The Chemical Society of Japan.
DOI： 10.1246/cl.2007.252
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Takenaka S., Umebayashi H., Tanabe E., Matsune H., Kishida M.
Journal of Catalysis 245 ( 2 ) 392 - 400 2007年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Catalysis
Silica-supported Ni catalysts were prepared by using water-in-oil typed microemulsion. By preparation using the microemulsion, Ni metal particles with diameters < ca. 5 nm were covered uniformly with silica layers with thickness of ca. 10 nm, whereas Ni metal particles were supported on the outer surface of silica by a conventional impregnation method. The Ni metal covered with silica (coat-Ni) showed excellent catalytic performance for the partial oxidation of methane into synthesis gas. Coat-Ni showed a high activity and a long life for the partial oxidation of methane at temperatures above 973 K to form CO and hydrogen, whereas Ni metal catalyst supported on silica was rapidly deactivated for the reaction. Ni K-edge XANES/EXAFS and temperature-programmed reduction for these catalysts showed that Ni metal particles in coat-Ni strongly interacted with silica. The strong interaction of Ni metal particles with silica would improve their catalytic performance for the partial oxidation of methane into synthesis gas. © 2006 Elsevier Inc. All rights reserved.
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One-pot synthesis and characterization of laccase-entrapped magnetic nanobeads 査読あり
Matsune H., Jogasaki H., Date M., Takenaka S., Kishida M.
Chemistry Letters 35 ( 12 ) 1356 - 1357 2006年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Chemistry Letters
We report the simple one-pot synthesis of magnetic nanoparticles coated with silica-gel layers that entrap laccase (Lc) by the water-in-oil microemulsion method. The amorphous porous structure of the silica layer enables the entrapped Lc to react with substrates in solution. The enzymatic activity is studied using Michaelis-Menten kinetics. The reusability of the magnetic nanoparticles is examined. Copyright © 2006 The Chemical Society of Japan.
DOI： 10.1246/cl.2006.1356
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Matsune H., Tago T., Shibata K., Wakabayashi K., Kishida M.
Journal of Nanoparticle Research 8 ( 6 ) 1083 - 1087 2006年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Nanoparticle Research
A nonionic reverse-micelle based approach is described for fabrication of a network structure consisting of chain-like arrays of gold nanoparticles followed by coating process with a uniform silica layer using a sol-gel method. The hexadecyl-poly (ethylene oxide-15) ether (designated C16E 15) is used as a template for this study. The effects of a water-to-surfactant molar ratio (w) as well as the concentration of tetraethyl orthosilicate ([TEOS]oil) are investigated on the resulting organized structures. © Springer Science+Business Media Inc. 2006.
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Asahi T., Volkov V., Matsune H., Kawai H., Masuhara H.
Proceedings - Electrochemical Society PV 2004-22 150 - 161 2006年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceedings - Electrochemical Society
We have developed a dark-field optical microspectrscopic system coupled with AFM measurement, and applied it to 1, 6-di(N-carbazolyl)-2-4-hexadiyne (DCHD) nanocrystal systems. We revealed clearly the size and shape dependent peak of the polymer-backbone electronic transition of individual poly-DCHD nanocrystals. It was found that the peak energy of the resonant Rayleigh scattering spectra shifted to a lower energy for nanocrystals having larger cross-section against its long axis. In situ observation of photopolymerization of individual monomer DCHD nanocrystals is also descried. It has been successfully demonstrated that the morphological of fibrous nanocrystal changes upon polymerization. Our single particle results demonstrate that far-field microscopy coupled with AFM is a reliable experimental approach for investigating optical properties and photochemistry of organic nanoparticles.
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Hori K., Matsune H., Takenaka S., Kishida M.
Science and Technology of Advanced Materials 7 ( 7 ) 678 - 684 2006年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Science and Technology of Advanced Materials
Pt-SiO2 catalysts were prepared by using water-in-oil type microemulsion. The catalysts were prepared by hydrolysis of tetraethylorthosilicate in the microemulsion containing Pt species, followed by calcination in air and reduction with H2. This preparation method for Pt-SiO2 provided Pt metal nanoparticles with a diameter of ca. 6 nm covered uniformly with silica layers, while a conventional impregnation method formed Pt metal particles supported on the silica surface. The Pt catalysts coated with silica (coat-Pt) showed different catalytic performance for the competitive oxidation of mixed hydrocarbons from Pt catalysts supported on silica (imp-Pt), i.e. in the competitive oxidation of methane and iso-butane, coat-Pt catalysts preferentially oxidized methane, while iso-butane was oxidized selectively over imp-Pt catalysts. The results of the adsorption of Ar on coat-Pt showed that silica in coat-Pt had porous structures of pore diameters <1 nm. Because the porous structure of silica, which wrapped Pt metal particles, controlled the diffusion rate of reactant molecules, coat-Pt showed a specific catalytic performance for competitive oxidation. © 2006.