研究者詳細 - 仁科　勇太

論文 - 仁科　勇太

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Hydrosilane-Assisted Formation of Metal Nanoparticles on Graphene Oxide 査読

Akinori Saito, Hiroshi Kinoshita, Ken-ichi Shimizu, Yuta Nishina

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 89 ( 1 ) 67 - 73 2016年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

Metal nanoparticles were formed on graphene oxide by a deposition process with hydrosilane, giving thin layer metal graphene oxide (metal/GO) composites. The particle size and catalytic activity could be controlled by varying the hydrosilane amount. Hydrosilane prevented the aggregation of GO layers by surface functionalization via silane coupling reaction. The metal/GO composites were evaluated as catalysts in hydrosilane oxidation.

DOI： 10.1246/bcsj.20150331

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Carbon-catalyzed Dehydrogenation of Indolines: Detection of Active Intermediate and Exploration of High-performance Catalyst 査読

Naoki Morimoto, Yasuo Takeuchi, Yuta Nishina

CHEMISTRY LETTERS 45 ( 1 ) 21 - 23 2016年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

Metal-free oxidation of indoline using molecular oxygen as an oxidant was investigated. Among various carbon-based catalysts, we found that reduced graphene oxide (rGO) was the most active. Superoxide radical was formed in the course of the reaction. Although graphene oxide (GO) did not function as a catalyst, rGO could be recycled at least 5 times without any structural change.

DOI： 10.1246/cl.150905

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黒鉛の酸化および還元による物性の制御

仁科勇太

炭素 2016 ( 271 ) 15 - 24 2016年

記述言語：日本語出版者・発行元：炭素材料学会

Oxidation of graphite produces graphite oxide and/or graphene oxide, both of which are abbreviated "GO". The preparation methods of these materials have been described by Brodie, Staudenmaier, and Hummers. Graphene oxide is widely recognized as a promising material in various fields, but its structure and composition has still not been fully controlled. In this article, general strategies to control the structure, particle size, and oxidation degree of graphene-like materials are introduced with emphasis on the oxidation of graphite by KMnO4 in H2SO4 (oGO) and the reduction of highly oxidized graphene oxide by hydrazine (rGO). Even though the oxygen content is the same, oGO and rGO have different properties, such as adsorption ability, oxidation ability, and electronic conductivity, because of differences in the persisting graphitic structure and defects. These results can be used as a guideline for the production of tailor-made GO. The current method of GO preparation is also discussed.

DOI： 10.7209/tanso.2016.15

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その他リンク： https://jlc.jst.go.jp/DN/JLC/20021713420?from=CiNii

Fast, scalable, and eco-friendly fabrication of an energy storage paper electrode 査読

Hirotaka Koga, Hidetsugu Tonomura, Masaya Nogi, Katsuaki Suganuma, Yuta Nishina

GREEN CHEMISTRY 18 ( 4 ) 1117 - 1124 2016年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Recent progress in portable and wearable electronics has promoted a growing demand for high-performance and flexible energy-storage devices that are abundant and affordable. Because reduced graphene oxide (rGO), originating from inexpensive graphite, serves as a higher-performance energy-storage electrode than conventional activated carbons and carbon nanotubes, research and development of rGO/polymer composite electrodes for flexible supercapacitors have become a center of attraction. However, the fabrication of rGO-based flexible electrodes frequently requires a long time with high-temperature treatment or toxic chemical treatment, resulting in the lack of scalability and eco-friendliness. Here we show a fast, scalable, and environment-compatible route to fabricate a high-performance rGO/cellulose paper supercapacitor electrode. Single-layer graphene oxide (GO) sheets and recycled waste pulp fibers were successfully fabricated into a paper composite by a well-established scalable papermaking process, followed by a room-temperature, additive-free, and millisecond-timescale flash reduction process. The as-prepared rGO/paper electrode had a high specific capacitance, up to 212 F g(-1), for an all paper-based flexible supercapacitor, comparable to those of state-of-the-art rGO-based electrodes, while dramatically decreasing the reduction time of GO from the conventional hour timescale to milliseconds. This work will pave the way for green, flexible, and mass-producible energy-storage paper in future wearable electronics.

DOI： 10.1039/c5gc01949d

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Investigations on tribological mechanisms of graphene oxide and oxidized wood-derived nanocarbons as water-based lubricating additives 査読

Hiroshi Kinoshita, Yuta Nishina

Tribology Online 11 ( 2 ) 235 - 241 2016年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Society of Tribologists

Graphene oxide (GO) contains graphitic single-layered sheets, while oxidized wood-based nanocarbon (oWNC) is composed of graphitic nanoshells. Since both materials are thoroughly oxidized with many oxygen-containing functional groups, both GOs and oWNCs form stable dispersions in water. We found that lubrication by dispersions of GOs and oWNCs in water resulted in very low friction coefficients below 0.04 with only slight plate surface wear using a steel plate and tungsten carbide ball. After lubrication, thick tribofilms are formed on the sliding surfaces, which would decrease the friction. In this study, in order to clarify the tribological mechanisms that result in such low friction coefficients, we have performed tribological tests and analyzed the tribofilms formed by dispersions of GO in water using confocal laser scanning microscopy (CLSM) with an optical data storage system, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The GO tribofilm is composed of many carbons and some oxygen, derived from the disordered and aggregated GO sheets. The GO tribofilm have higher hardness and hydrophilic properties than the steel plates, which would provide low friction and wear. It is found that both the GO tribofilm and GOs are necessary to achieve the lowest possible coefficient of friction. It is likely that the oWNC tribofilm has similar friction and wear decreasing effects to that of the GO dispersion.

DOI： 10.2474/trol.11.235

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The Scaevola frutescen (Mill.) Krause Dried-Leaves Extract as a Potential Natural Reduction System for Synthesis of Gold Nanoparticles and Their Evaluation for Antibacterial of Eschericia coli 査読

Salprima S. Yudha, Eka Angasa, Totok Eka Suharto, Yuta Nishina, Zulfikri Achid Mardlia, Sipriyadi

6TH NANOSCIENCE AND NANOTECHNOLOGY SYMPOSIUM (NNS2015) 1710 2016年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：AMER INST PHYSICS

Many reports recently show that some plant and animal extracts were useful to prepare some desired materials. In line with the statement, this report will present a bioresources candidate that can be used for green preparation of gold nanoparticles. The Scaevola fruteschen (Mill.) Krause was obtained from Enggano island, Bengkulu Province, Indonesia. The current research include synthesis, characterization and application study of the obtained nanoparticles in their original medium/reduction system as antibacterial agent of Escherichia coli. Besides that, the interaction study of the nanoparticles solution with Pb2+ ions was also studied. The results, shows that the present reduction system (aqueous extract of the plant leaves) successfully reduced gold (III) ions to gold metals as shown by new peak at 544 nm in spectrophotometry analysis. The average nanopartiles size was 96 nm based on Particles Size Analyzer (PSA) result. The stability study revealed that the nanoparticles solution was not stable in the persence of Pb(OAc)(2) at high concentration. The nanoparticles were effective enough toward E. coli as shown by inhibition zone that indicates the degree of sensitivity of bacteria to nanoparticles.

DOI： 10.1063/1.4941483

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酸化グラフェンの光還元によるsp3からsp2への構造ダイナミクス

羽田真毅, 仁科勇太, 林靖彦, 徳永智春, 腰原伸也, 一柳光平, 野澤俊介, 足立伸一, 片山郁文, 鈴木貴之, 南康夫, 武田淳

日本物理学会講演概要集 71 1279 - 1279 2016年

記述言語：日本語出版者・発行元：一般社団法人日本物理学会

<p>酸化グラフェンはグラフェンの化学誘導体であり、光照射や加熱、還元剤の添加によりグラフェンに近い特性を持つ物質に変化することが知られている。この酸化グラフェンは、液中における化学操作が可能となるため、グラフェン誘導体に関する幅広い応用へと期待されている。本講演では、フェムト秒時間分解電子線回折法及びシングルショット過渡透過率測定によって解明した酸化グラフェンの光還元反応のダイナミクスを議論する。</p>

DOI： 10.11316/jpsgaiyo.71.2.0_1279

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Preparation of graphene oxide and its metal composite materials as catalysts for organic reactions

Nishina, Y., Morimoto, N.

Graphene Science Handbook 2-6 2016年

Synthesis of 2-Arylphenol Derivatives through a One-Pot Suzuki-Miyaura Coupling/Dehydrogenative Aromatization Sequence with Pd/C Catalysis 査読

Kotaro Kikushima, Yuta Nishina

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2015 ( 26 ) 5864 - 5868 2015年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

One-pot synthesis of 2-arylphenols starting from 2-iodo-2-cyclohexen-1-one and arylboronic acids through sequential Suzuki-Miyaura coupling/dehydrogenative aromatization with Pd/C catalysis has been developed. A range of arylboronic acids serve as substrates, including those containing electron-donating or electron-withdrawing groups. Additionally, one-pot synthesis of di- or trisubstituted phenols bearing a phenyl group at the ortho position are also generated by using 2-iodo-2-cyclohexen-1-one derivatives as substrate. In the present method, commercially available and easily removable Pd/C was employed as a catalyst without any ligands. The operationally simple procedure and accessible conditions were used to provide modified phenols as the sole product in moderate to high yields.

DOI： 10.1002/ejoc.201500723

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Metal free C-H coupling of aromatic compounds by graphene oxide activated by acidic additives 査読

Nishina Yuta, Morimoto Naoki, Morioku Kumika

ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 250 2015年8月

Production of Gold Nanoparticles (AuNPs) from Chloroaurate Ions Using Aqueous Extract Of Air-Dried Premna obtusifulia Leaves 査読

Yudha Salprima S, Angasa Eka, Suharto Totok Eka, Nishina Yuta, Mardlia Zulfikri Achid

RESEARCH JOURNAL OF PHARMACEUTICAL BIOLOGICAL AND CHEMICAL SCIENCES 6 ( 4 ) 1802 - 1806 2015年7月

Highly durable carbon-supported Pt catalysts prepared by hydrosilane-assisted nanoparticle deposition and surface functionalization 査読

Akinori Saito, Hiromi Tsuji, Iwao Shimoyama, Ken-ichi Shimizu, Yuta Nishina

CHEMICAL COMMUNICATIONS 51 ( 27 ) 5883 - 5886 2015年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Hydrosilane enabled the formation of Pt nanoparticles and the silane functionalization of a carbon support material in one pot. The metal/Si-modified carbon composites are highly durable during catalytic methane oxidation.

DOI： 10.1039/c4cc10298c

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Facile identification of the critical content of multi-layer graphene oxide for epoxy composite with optimal thermal properties 査読

Tianle Zhou, Shijo Nagao, Tohru Sugahara, Hirotaka Koga, Masaya Nogi, Katsuaki Suganuma, Thi Thi Nge, Yuta Nishina

RSC ADVANCES 5 ( 26 ) 20376 - 20385 2015年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Multi-layer graphene oxide (MGO) has attracted considerable interest in conductive polymer composites. However, in most cases the optimal MGO content is determined using a complex procedure. Avoiding the complicated work of processing polymerized samples followed by testing various properties, here a facile strategy is proposed to directly identify the critical MGO content among formulations for epoxy composites with optimal thermal properties, simply by monitoring the "unusual" nonlinear MGO content-dependent cure behaviors, as well as the "unusual" pattern of double-peak curing curves. The formation mechanism of the double-peak pattern was explored, with emphasis on studying the epoxy/MGO reaction using a modified Shrinking Core Model. The optimal content determined in this work 2 wt% MGO) was verified by the thermal properties (thermal conductivity, structural thermal stability and coefficient of thermal expansion) of MGO/epoxy composites. Based on the inherent relationship between the effect of MGO percolating chains on the thermal polymerization behavior and the resulting thermal properties, this strategy can be easily extended to different kinds of conductive MGO/polymer composites.

DOI： 10.1039/c4ra15881d

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Targeted kinetic strategy for improving the thermal conductivity of epoxy composite containing percolating multi-layer graphene oxide chains 査読

Zhou, T., Koga, H., Nogi, M., Sugahara, T., Nagao, S., Nge, T.T., Suganuma, K., Cui, H.-W., Liu, F., Nishina, Y.

Express Polymer Letters 9 ( 7 ) 608 - 623 2015年

Tribological properties of graphene oxide as a lubricating additive in water and lubricating oils 査読

Kinoshita Hiroshi, Ono Hideki, Alias Aidil Azli, Nishina Yuta, Fujii Masahiro

MECHANICAL ENGINEERING JOURNAL 2 ( 6 ) 2015年

Polycyclic N-Heterocyclic Compounds 75: Synthesis and Anti-platelet Evaluation of 2,4-Disubstituted 5,6-Dihydro[1]benzofuro[3’,2’:2,3]oxepino[4,5-d]pyrimidines 査読

Okuda Kensuke, Takano Jun-ichi, Hirota Takashi, Sasaki Kenji, Nishina Yuta, Ishida Hiroyuki

JOURNAL OF HETEROCYCLIC CHEMISTRY 51 ( 3 ) 661 - 668 2014年5月

Tribological properties of monolayer graphene oxide sheets as water-based lubricant additives 査読

Hiroshi Kinoshita, Yuta Nishina, Aidil Azli Alias, Masahiro Fujii

CARBON 66 720 - 723 2014年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Application and tribological properties of graphene oxide (GO) monolayer sheets as additives in water-based lubricants were investigated. The lubricating fluids were applied to a sintered tungsten carbide ball and stainless steel flat plate. It was found that adding GO particles into water improved lubrication and provided a very low friction coefficient of approximately 0.05 with no obvious surface wear after 60,000 cycles of friction testing. GO adsorption occurred on the lubricated surfaces of both the ball and flat plate, suggesting GO sheets may behave as protective coatings. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbon.2013.08.045

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Facile preparation of Pd nanoparticles supported on single-layer graphene oxide and application for the Suzuki-Miyaura cross-coupling reaction 査読

Shun-ichi Yamamoto, Hiroshi Kinoshita, Hideki Hashimoto, Yuta Nishina

NANOSCALE 6 ( 12 ) 6501 - 6505 2014年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Pd nanoparticles supported on single layer graphene oxide (Pd-slGO) were prepared by gentle heating of palladium(II) acetate (Pd(OAc)(2)) and GO in ethanol that served as a mild reductant of the Pd precursor. Pd-slGO showed a high catalytic performance (TON and TOF = 237 000) in the Suzuki-Miyaura cross-coupling reaction.

DOI： 10.1039/c4nr00715h

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Fine tuning of the sheet distance of graphene oxide that affects the activity and substrate selectivity of a Pd/graphene oxide catalyst in the Heck reaction 査読

Akinori Saito, Shun-Ichi Yamamoto, Yuta Nishina

RSC Advances 4 ( 104 ) 59835 - 59838 2014年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Royal Society of Chemistry

The interlayer distance of graphene oxide (GO) in a Pd/GO composite could be tuned using cationic surfactants. The distance becomes larger when a large surfactant is used. The catalytic activity in Heck reactions dramatically improved using the surfactant-modified Pd/GO catalyst. Substrate selectivity could also be improved by adjusting the size of the surfactant to increase accessibility of substrates to the active catalytic centre.

DOI： 10.1039/c4ra10512e

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Application of Heterogeneous Catalysts for Organic Synthesis by Controlling the Oxidation State of Metal Species 査読

Yuta Nishina

JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN 71 ( 12 ) 1307 - 1308 2013年12月

記述言語：日本語出版者・発行元：SOC SYNTHETIC ORGANIC CHEM JPN

One of the important research topics in the synthesis of pharmaceuticals and fine chemicals is to convert homogeneous reactions to heterogeneous versions by immobilization of metal species on polymer or inorganic supports. The oxidation state of the metal species can affect the character and reactivity of the catalyst. Recently, chemists have gained excellent techniques to control particle size and oxidation state of metal species, which has led to the development of new heterogeneous catalysts for organic reactions.

DOI： 10.5059/yukigoseikyokaishi.71.1307

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