HANADA, Nobuko

写真a

Affiliation

Faculty of Science and Engineering, School of Advanced Science and Engineering

Job title

Assistant Professor

Concurrent Post 【 display / non-display

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Research Experience 【 display / non-display

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    Hiroshima University Graduate School of Advanced Sciences of Matter, Department of Quantum Matter

 

Research Areas 【 display / non-display

  • Chemical reaction and process system engineering

  • Structural materials and functional materials

Papers 【 display / non-display

  • Numerical simulation of heat supply and hydrogen desorptionby hydrogen flow to porous MgH2 sheet

    Keisuke Yoshida, Kosuke Kajiwara, Hisashi Sugime, Suguru Noda, Nobuko Hanada

    Chemical Engineering Journal     129648 - 129648  2021.04  [Refereed]

    DOI

  • Electrolysis of ammonia in aqueous solution by platinum nanoparticles supported on carbon nanotube film electrode

    Nobuko Hanada, Yusuke Kohase, Keisuke Hori, Hisashi Sugime, Suguru Noda

    Electrochimica Acta   341   136027 - 136027  2020.05  [Refereed]

    DOI

  • Effect of CO2 on hydrogen absorption in Ti-Zr-Mn-Cr based AB2 type alloys

    Nobuko Hanada, Hirotaka Asada, Tessui Nakagawa, Hiroki Higa, Masayoshi Ishida, Daichi Heshiki, Tomohiro Toki, Itoko Saita, Kohta Asano, Yumiko Nakamura, Akitoshi Fujisawa, Shinichi Miura

    Journal of Alloys and Compounds   705   507 - 516  2017.05  [Refereed]

    DOI

  • Material transformation of alumina and influence on leakage current by application of DC high voltage at high temperatures

    Satoshi Kawato, Nobuko Hanada, Masashi Mitsui, Masayoshi Ishida

    IEEJ Transactions on Fundamentals and Materials   137 ( 12 ) 685 - 692  2017

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    In order to investigate a material transformation of alumina (Al2O3) and an influence on leakage current by application of high DC voltage at high temperatures, the leakage current of two alumina samples were measured for 100 hours and the elemental analyses were carried out. The leakage current tended to decrease, and the electrical conductivity decreased with increasing applied voltage. The activation energies of electrical conduction of two samples were nearly equal. Thus, the reproducibility of these results was confirmed. After the experiments, deposits of impurities contained in alumina were observed in the surrounding area of the positive electrode. Furthermore, Na, which was contained in Pt paste used for preparing the electrodes, can be a charge career of alumina because it was detected from only negative electrodes. Therefore, the reason why the leakage current decreased is the decrease in the amount of charge careers because of the deposits of impurities.

    DOI

  • dc Voltage Insulating Properties of Various Inorganic Materials in Hydrogen Atmosphere at High Temperatures

    Koichi Takahashi, Nobuko Hanada, Masayoshi Ishida

    ELECTRICAL ENGINEERING IN JAPAN   193 ( 4 ) 1 - 8  2015.12  [Refereed]

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    In this study, the dc voltage insulating properties in a hydrogen atmosphere at high temperatures (600 degrees C to 850 degrees C) were evaluated for alumina (Al2O3), magnesia (MgO), silicon nitride (Si3N4), and mica (KMg3(Si3Al)O-10(OH)(2)) to comprehend the difference in the insulating properties of oxide, nitride, and minerals. The activation energies of the electrical conductivity of alumina and magnesia in hydrogen were larger than those in air. On the other hand, the electrical conduction values for silicon nitride and mica in hydrogen were the same as those in air. Therefore a low oxygen partial pressure would have some influence on the electrical conduction of oxides. Increasing the temperature did not result in a large change in the electrical conduction mechanism in any of the materials in either atmosphere. The maximum partial discharge (PD) in hydrogen tended to increase compared to that in air at high voltage. The applied voltage at which the maximum amount of PD started to increase rapidly became lower with increasing temperature in all materials and in both atmospheres. The total amount of PD tended to decrease with increasing temperature in all materials and in both atmospheres. However, above a certain temperature, the total amount of PD either increased or showed a slight decrease.

    DOI

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Research Projects 【 display / non-display

  • Overvoltage decrease of liquid ammonia electrolysis by electrode of nitrogen absorbing material with electrocatalysts

    Project Year :

    2016.04
    -
    2018.03
     

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    The anode reaction with nitrogen desorption has much larger overpotential than that of a cathode reaction in the electrolysis of liquid ammonia for hydrogen generation. The anode reaction properties were investigated using mono catalyst and binary catalyst electrodes. The catalyst effect on anode reaction was investigated by focusing on the metal nitride formation enthalpy which corresponds to the strength of metal-nitrogen bond. By plotting the current density at the low potential against the metal nitride formation enthalpy, the volcano plot was obtained. The binary metal catalysts of Fe and Pt (Fe-Pt) composited in nanoparticle size or atomic size (alloyed) were prepared. The current density of both Fe-Pt electrodes were lower than that of mono-Fe and mono-Pt at the low potential

  • Dielectrical reliability improvement for increasing output of solid oxide fuel cell system

    Project Year :

    2015.04
    -
    2018.03
     

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    The electrical insulation properties and morphological change of alumina in redox gas atmosphere of solid oxide fuel cells (SOFC) at high temperatures (600-900℃) were evaluated. It is shown that difference of gases greatly effects these properties. In the study on distance dependence of creepage electrical insulation properties, it was clarified that properties are not proportional to creepage distance. In applying inorganic materials to space charge distribution measurement, the distribution tended to reverse in most materials. Such a tendency was not observed in some inorganic materials which have different electrical properties, and this suggests the electrical properties have a large effect as a factor

  • Design of high efficiency electrolysis cell for liquid ammonia utilization as hydrogen storage carrier

    Project Year :

    2012.04
    -
    2014.03
     

     View Summary

    The overvoltage reduction effects of electrode morphology and materials on liquid ammonia electrolysis were investigated to design high efficiency electrolysis cell for generating hydrogen from liquid ammonia. For Pt-black electrodes prepared by electrodeposition, it is clarified that the overvoltage reduction does not relate to the electrode surface area, but relates to both of Pt deposition amount and size of deposited Pt particles. For the electrolysis by using Pt plate electrode, anode overvoltage is five times as large as cathode one. Ammonia electrolysis with the emission of hydrogen gas was performed at 0.1 V around theoretical electrolysis voltage by adapting Pt-Ru electrode which can reduce the anode overvoltage

  • Insulating design for solid oxide fuel cells based on dielectrical properties at high temperatures

    Project Year :

    2011.04
    -
    2014.03
     

     View Summary

    The dielectric properties of inorganic materials in anode gas atmosphere of solid oxide fuel cells (SOFC) at high temperatures (600-850 deg C) were evaluated, and design concepts of primary insulation of SOFC are proposed. The evaluation of DC voltage insulating properties for various inorganic materials shows that magnesia is the best insulation material among them because it has the largest insulation resistance. The effects of anode gas component on dielectric properties were investigated for primary insulation of SOFC composed of magnesia mainly. It is clarified that hydrogen gas itself or heat and flame of hydrogen combustion generated by hydrogen leak degrade primary insulation performance

Specific Research 【 display / non-display

  • 液体アンモニア電気分解のカソード反応機構解明および高電流効率化

    2020   佐々木

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    高容量水素貯蔵のキャリアとしてアンモニアに着目し、液体アンモニアから室温で電気分解により水素生成を行った。電気分解が起きていることは確認されているが、電流効率は85%程度であり100%に達していない。この原因がカソード反応における溶媒和電子発生の副反応にあるという仮説のもと、電流効率と溶媒和電子発生の関係を調べた。液体アンモニア電気分解の定電位測定において電位を-0.3、-0.5、-0.7 V vs H2/NH3 と変化させた結果、低電位であるほど溶媒和電子が多く発生することが観察された。しかし、-0.3 Vと-0.5 Vでの定電位測定の電流効率は82.9 %、82.5%とほとんど同じであったことから、低電流効率の要因は他にも存在することが示唆された。

  • オンボード水素供給に向けたアンモニア電気分解の高電流密度・高効率化

    2020   野田優, 赤木夏帆, Patil Neel, 佐々木隆一, 沓抜佳奈

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    高容量水素貯蔵のキャリアとしてアンモニアに着目し、液体アンモニアもしくはアンモニア水溶液から電気分解により水素を生成する。本研究では、高電流密度を低電圧で出力するために、2元系アノード電極触媒の検討を行った。液体アンモニア電気分解反応に対して、比較的窒素との結合強さが近い金属の組み合わせであるNi-Pt触媒を適用した。Ni板にPtをスパッタしてアニール処理した電極を用い、表面積変化の影響を除去して評価を行った。Pt単体触媒比べてNi-Pt の二元系触媒はアノード反応に対して効果が見られなかった。Ni とPt の組み合わせでは、N との結合が強いNi に律速が支配されてしまい二元系の効果が見られない可能性が高い。

  • 水素生成のための液体アンモニアおよび水溶液中アンモニア電気分解特性の向上

    2019   野田優, 小長谷優佑, 赤木夏帆, Patil Neel

     View Summary

    高容量水素貯蔵のキャリアとしてアンモニアに着目し、液体アンモニアもしくはアンモニア水溶液から電気分解により水素を生成した。本研究では、高電流密度を低電圧で出力する高効率な電気分解セル構築のための基礎検討を行った。液体アンモニア電気分解反応に対して、過電圧の高いアノード反応特性の向上のために、触媒金属の窒素との結合のしやすさに着目した。窒素との結合が中間の強さである触媒金属が高電流密度を示すことが明らかになった。また、アンモニア水溶液電気分解反応に対しては、電極の反応場を3次元的に拡張するために白金ナノ粒子を担持したカーボンナノチューブ膜電極を適用し、アノード電流密度の増大を実現した。

  • 液体アンモニア電気分解への電極触媒を内包したカーボンナノチューブ膜電極の適用

    2017  

     View Summary

    Ammonia (NH3), which has high volumetric hydrogen density and high gravimetric hydrogen density, is one of the promising media to store and transport hydrogen. We have performed the direct electrolysis of liquid ammonia for hydrogen generation. This method would be able to decompose ammonia itself by keeping high hydrogen density at room temperature. In this study 3D structured electrode with platinum nanoparticles supported on carbon nanotube (CNT) film was fabricated to increase the current density and decrease anode over potential for liquid ammonia electrolysis. The platinum nanoparticles were loaded on CNT by reducing Pt ion in Ethylene Glycol at 100 to 180 ºC. The smaller Pt nanoparticles were synthesized by increasing loading temperature. The average particle size of Pt nanoparticles on CNT was 3.6 nm and surface area of Pt was several hundred times of the electrode area. The electrode of Pt nanoparticles on CNT decreased anode overpotential and increased the current density at lower potential in ammonia electrolysis.

 

Syllabus 【 display / non-display

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