ISHIHARA Akimitsu

Affiliation

Institute of Advanced Sciences

Job Title

Specially Appointed Professor

Related SDGs




ORCID  https://orcid.org/0000-0002-7515-7374

Degree 【 display / non-display

  • Doctor of Engineering -  Yokohama National University

Campus Career 【 display / non-display

  • 2015.01
    -
    Now

    Duty   Yokohama National UniversityInstitute of Advanced Sciences   Specially Appointed Professor  

 

Books 【 display / non-display

  • Nanocarbons for Energy Conversion: Supramolecular Approaches (Nanostructure Science and Technology)

    Yuta Nabae and Akimitsu Ishihara (Part: Joint Work , Range: Chapter 11 )

    Springer   2019 ISBN: 3319929151

  • Fuel Cells and Hydrogen From Fundamentals to Applied Research

    Akimitsu Ishihara and Ken-ichiro Ota (Part: Joint Work )

    Elsevier  2018 ISBN: 0977634876

  • Advances in Hydrogen Production, Storage and Distribution

    K. Ota, K. Matsuzawa, S. Mitsushima, A. Ishihara (Part: Joint Work )

    Woodhead publising  2014

  • State-of-the-art Fuel Cells and Hydrogen Technology in Japan

    石原顕光ほか (Part: Joint Work )

    Fuel Cell Development Information Center (FCDIC)  2014

  • Non-Noble Metal Fuel Cell Catalysts

    A. Ishihara, H. Imai, K. Ota (Part: Joint Work , Range: Chap.5, Transition metal oxides, carbides, nitrides, oxynitrides, and carbonitrides for O2 reduction reaction electrocatalysts for acid PEM fuel cells, 酸化物系酸素還元触媒について分担執筆 )

    Wiley-VCH  2013

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Papers 【 display / non-display

  • Catalytic activity of zirconia on zirconium for the oxygen evolution reaction in potassium hydroxide

    K. Matsuzawa, A. Ishihara, A. Oishi, S. Mitsushima, K. Ota

    Materials Science and Engineering: B ( Elsevier )  267   115112   2021.03  [Refereed]

    Joint Work

     View Summary

    It has been reported that the Ni anode electrode used in alkaline water electrolysis (AWE) is degraded when the fluctuating electricity produced by renewable energy (wind and solar power) systems is used. To develop alternative materials, we focused on zirconium oxide because of its high chemical stability, and investigated its catalytic activity for the oxygen evolution reaction (OER) on zirconium oxides on a zirconium plate fabricated by both air oxidation (ZrO2/Zr) and arc-plasma deposition (ZrO2/Zr_APD). From cross-sectional observations and electrochemical results, the mixed tetragonal and monoclinic structure of ZrO2 was related to its catalytic activity for the OER. ZrO2/Zr_APD showed obviously a higher activity than ZrO2/Zr. The reason for this is that the particles are better dispersed in ZrO2/Zr_APD than in ZrO2/Zr, so the electrochemical surface area of ZrO2/ Zr_APD seems to be larger than that of ZrO2/Zr.

    DOI

  • Control of surface area and conductivity of niobium-added titanium oxides as durable supports for cathode of polymer electrolyte fuel cells

    Y.-B. Ma, T. Nagai, Y. Inoue, K. Ikegami, Y. Kuroda, K. Matsuzawa, Teko W. Napporn, Y. Liu, S. Mits … Show more authors

    Materials and Design ( Elsevier )  203   109623   2021.03  [Refereed]

    Joint Work

     View Summary

    Niobium-added titanium oxide is a promising candidate as a substitute carbon support for cathodes of PEFCs. Nb-added TiO2 can act as a support for platinum nanoparticles to enhance the oxygen reduction reaction (ORR) ac-tivity and durability under acidic conditions. Nb-added TiO2 supports with the desired surface area (10–130 m2 g−1) and conductivity (10−7–10−2 Scm−1) were prepared by changing the amount of Nb and the heat treatment conditions. First, we conducted a systematic investigation with changes in the amount of niobium addition, heat-treatment temperature, and time under a pure hydrogen atmosphere to reveal the physicochem-ical factors that govern the surface area and conductivity. Finally, we successfully proposed a procedure to pre-pare highly durable Nb-added TiO2 supports with the desired surface area and conductivity by controlling the amount of niobium addition, heat-treatment temperature, and time under hydrogen. The charges of the double layer were almost unchanged after 5000 cycles of an accelerated durability test (ADT).

    DOI

  • Effect of Semiconducting Properties of Oxide-Based Compounds on Oxygen Reduction Activity in Acidic Media

    A. Ishihara, J. Hirata, T. Nagai, Y. Kuroda, K. Matsuzawa, A. Imanishi, S. Mitsushima, Y. Takasu, a … Show more authors

    ECS Transaction ( The Electrochemical Society )  98 ( 9 )   457 - 464   2020.10  [Refereed]

    Single Work

     View Summary

    Effect of semiconducting properties of group 4 and 5 oxide-based films on catalytic activity of oxygen reduction reaction (ORR) has been investigated. In case of n-type semiconductor oxide catalysts, there are two reasons that the ORR activities are apparently observed to be low; one is that there are few active sites with high quality on the surface, another is that although the relative active sites are exists on the surface the Schottky barrier formed in the space charge layer of the oxides suppresses the electron transfer from bulk to the surface. The positive correlation between flat-band potential and onset potential for the ORR of thick oxide films composed of titanium-niobium, -tantalum, and -zirconium oxides was observed, indicating that the ORR activities were governed by the semiconducting properties of the films.

    DOI

  • P-Doped SnO2 Powder as a Support for PEFC Cathode

    Y. Inoue, K. Matsuzawa, Y. Ma, Y. Ohgi, T. Nagai, Y. Kuroda, S. Yamamoto, and A. Ishihara

    ECS Transaction ( The Electrochemical Society )  98 ( 9 )   565 - 572   2020.10  [Refereed]

    Joint Work

     View Summary

    A possibility of commercial P-doped SnO2 was evaluated as a non-carbon support for PEFC cathodes. The effect of heat-treatment under various conditions on the physical properties of the P-doped SnO2 was investigated. The P-doped SnO2 was sensitive by the heat-treatment in reductive atmosphere, 4%H2/Ar. The surface area was hardly affected by the heat-treatment in air or Ar even at high temperature such as 900 °C. On the other hand, the conductivity was dramatically affected by the atmosphere during the heat-treatment. The heat-treatment in Ar at higher temperature rather increased in the conductivity, whereas the heat-treatment in air caused the drastic decrease in the conductivity. This difference might be responsible for the formation and extinction of the oxygen vacancies.

    DOI

  • Factors Affecting ORR Activity of Nb-Added TiOx Catalyst Using Carbon Support for PEFC

    Y. Adachi, T. Nagai, Y. Ohgi, Y. Kuroda, K. Matsuzawa, S. Mitsushima, K. Ota, and A. Ishihara

    ECS Transaction ( The Electrochemical Society )  98 ( 9 )   555 - 563   2020.10  [Refereed]

    Joint Work

     View Summary

    Cup-stacked carbon nanotubes (CSCNTs) were covered with niobium-added titanium oxide by hydrolysis method to increase effective surface area of the oxides. In addition, reductive heat-treatment was performed to produce the active sites for the oxygen reduction reaction (ORR). The use of CSCNTs as supports was found to be effective to form the electron conductive path. The ORR currents of the Nb-added titanium oxide supported by CSCNTs significantly larger than those of Nb-added titanium oxide powder mixed with Ketjenblack. On the other hand, the ORR current at 0.6 V had maximum at the heat-treatment temperature of 800 °C. We focused on the ratio of Ti3+ of the catalysts and found that the positive correlation between the ratio of Ti3+ and the ORR current density at 0.6 V. Therefore, it was found that the formation of the oxygen vacancies on the oxide surface strongly affected the ORR activity.

    DOI

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Review Papers 【 display / non-display

  • Oxide-based oxygen reduction reaction electrocatalysts

    Akimitsu Ishihara and Ken-ichiro Ota

      67 ( 7 ) 42 - 45   2019.06

    Introduction and explanation (commerce magazine)   Joint Work

  • Hydrogen Energy System and Environmental Impact Factor

    K.Ota, A.Ishihara, K.Matsuzawa and S. Mitsushima

    Electrochemistry   78   2010

    Introduction and explanation (others)   Joint Work