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Engineering educational research section Applied Chemistry Program |
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OKUYAMA Yuji
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Research Areas 【 display / non-display 】
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Nanotechnology/Materials / Inorganic compounds and inorganic materials chemistry
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Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electron device and electronic equipment
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Nanotechnology/Materials / Metals production and resources production
Papers 【 display / non-display 】
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Murakami T., Matsumoto N., Li K., Mori M., Kobayashi S., Yamauchi K., Mikami Y., Kuroha T., Okuyama Y., Araki T.
International Journal of Hydrogen Energy 203 2026.1
Publishing type：Research paper (scientific journal) Publisher：International Journal of Hydrogen Energy
Protonic ceramic fuel cell (PCFC) performance is sensitive to H<inf>2</inf>O partial pressure, and transient response may be limited by electrode kinetics, bulk diffusion, or gas diffusion. We investigate the transient response of PCFCs under changes in H<inf>2</inf>O partial pressure on the H<inf>2</inf> side, using practical electrolyte thicknesses of 6, 13, and 24 μm at 500–700 °C. By combining high-frequency resistance (HFR) measurements with analysis based on the Fourier number, we elucidate the relationship between the HFR response and electrolyte thickness. The results show that the HFR time constant depends approximately linearly on the square of the electrolyte thickness. Moreover, the HFR time constant exhibits an Arrhenius-type temperature dependence. The results highlight bulk diffusion within the electrolyte as the dominant contributor to the transient behavior, and provide quantitative insight into the coupling of electrolyte thickness, operating temperature, and transient response, and offer guidance for optimizing practical PCFC design.
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奥山 勇治
Journal of Materials Chemistry A 13 35480 - 35488 2025.9
Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)
To clarify the elementary reactions of multiple impedance components in fuel cell electrodes, the impedance characteristics of Ni anode-supported fuel cells with BaZr0.8Yb0.2O3−δ and Zr0.84Y0.16O2−δ electrolytes were evaluated using BaZr0.3Yb0.2Co0.5O3−δ as the cathode. The elementary reactions were identified by separating impedance components based on isotope effects during proton/deuteron substitution. Distribution of relaxation time analysis showed that the electrode impedances of the proton-conducting ceramic fuel cells (PCFCs) and solid-oxide fuel cells (SOFCs) could be separated into five components. The isotope effect in the impedance was investigated by replacing the anode gas from H2O–H2 to D2O–D2. For PCFCs, isotope effects appeared in two high-frequency components under open-circuit voltage (OCV), indicating their relation to the anodic reaction; however, isotope effects appeared in the lowest-frequency component under bias (0.85 V). This component was attributable to water vapor formation in PCFCs. By contrast, isotope effects were observed in the three middle-frequency components under bias (0.85 V) in SOFCs, indicating their relation to the anodic reaction; however, no isotope effects appeared in the highest-frequency component among three middle-furequency components under OCV. This component was attributed to water vapor formation in SOFCs.
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Mochammad W., Fukunaga T., Norsingha P., Nagamine M., Kiyoshi K., Inoue K., Okuyama Y.
ACS Sustainable Resource Management 2 ( 8 ) 1373 - 1378 2025.8
Publishing type：Research paper (scientific journal) Publisher：ACS Sustainable Resource Management
A hydrogen sensor utilizing proton-conducting ceramics was investigated for real-time monitoring of biohydrogen produced from soybean food wastewater using Clostridium neuense strain SDL48. Biohydrogen production began approximately 42 h after inoculation with strain SDL48, eventually reaching a concentration where hydrogen accounted for 43% of the gas phase. Additionally, the biohydrogen was purified using proton-conducting ceramics, successfully yielding hydrogen of high purity, qualifying it as pure hydrogen.
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OKUYAMA Yuji
Denki Kagaku 93 ( 1 ) 43 - 43 2025.3
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Electrochemical Society of Japan
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Li K., Murakami T., Nagata Y., Mikami Y., Yamauchi K., Kuroha T., Okuyama Y., Mizutani Y., Mori M., Araki T.
Applied Energy 381 2025.3
Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Energy
Protonic ceramic fuel cells (PCFCs) have garnered significant interest due to their theoretically high fuel utilization and excellent energy efficiency at intermediate temperatures (400–600 °C). While the performance of PCFCs has improved dramatically in recent years, the system electrical efficiency is often lower than the corresponding cell energy efficiency due to energy loss in a PCFC system. This study focuses on achieving >70% system electrical efficiency (lower heating value-LHV) in a H2-powered PCFC system. The required property values such as the conductivities and diffusion coefficients of proton and hole in the electrolyte, as well as the exchange current densities and reaction resistances at electrodes are revealed through a validated numerical model compared to the experimental results of a high-performance PCFC. It offers significant empirical insights for advancing high-performance PCFCs capable of achieving >70% system electrical efficiency.
Books 【 display / non-display 】
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カーボンニュートラルに向けた水素製造・P2Gと関連技術の最新動向
奥山勇治（ Role： Contributor , 第3章 プロトン伝導性セラミックスを用いた純水素製造）
シーエムシーリサーチ 2022.12
Language：Japanese Book type：Scholarly book
MISC 【 display / non-display 】
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機械学習を用いた ペロブスカイト型 酸化物中のプロトン 伝導度予測 Invited Reviewed
奥山勇治、堂園航汰
セラミックス 58 ( 11 ) 727 - 731 2023.11
Authorship：Lead author, Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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Phase stability of Ba(Zr,Yb)O<sub>3-δ</sub>-based perovskite electrolytes under a fabrication process
松田マリック隆磨, 小林駿, 森昌史, 島田寛之, 鷲見裕史, 水谷安伸, 奥山勇治, 見神祐一, 山内孝祐, 黒羽智宏
燃料電池シンポジウム講演予稿集(CD-ROM) 30th 2023
Publishing type：Rapid communication, short report, research note, etc. (scientific journal)
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プロトン伝導性セラミックスを用いた電気化学デバイス Invited Reviewed
奥山勇治
セラミックス 57 ( 11 ) 10 - 714 2022.11
Authorship：Lead author, Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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コヒーレントテラヘルツパルスでみる燃料電池で用いられる固体電解質内の高速イオン伝導
永井正也、奥山勇治、可児幸宗
レーザー研究 ( 50 ) 198 - 201 2022
Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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20 ( 4 ) 80 - 91 2021
Language：Japanese Publishing type：Rapid communication, short report, research note, etc. (scientific journal)
Presentations 【 display / non-display 】
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PCFC材料開発の現状と将来展望 Invited
奥山勇治
セラミックス協会年会サテライトミーティング ワークショップ 2025.3.5
Event date： 2025.3.5 - 2025.3.7
Language：Japanese Presentation type：Oral presentation (invited, special)
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機械学習を活用した固体酸化物形燃料電池材料の探索 Invited
奥山勇治、川上廉太、盛満優雅、東雲遥香、堂園航汰
セラミックス協会年会科学技術委員会企画インフォマティクスセッション 2025.3.6
Event date： 2025.3.5 - 2025.3.7
Language：Japanese Presentation type：Oral presentation (invited, special)
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Yb添加ジルコン酸バリウムを電解質とした燃料電池のカソード開発状況
奥山勇治、西屋智皓、東雲遥香、春日圭太、見神祐一、山内孝祐、黒羽智宏
第33回SOFC研究発表会 2024.12.19
Event date： 2024.12.19 - 2024.12.20
Language：Japanese Presentation type：Oral presentation (general)
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Yb添加ジルコン酸バリウムを用いた燃料電池における電解質表面処理の効果
奥山勇治、原田佳明、見神祐一、山内孝祐、黒羽智宏
第50回固体イオニクス討論会 2024.12.10
Event date： 2024.12.9 - 2024.12.11
Language：Japanese Presentation type：Oral presentation (general)
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Hydrogen Isotope Effects on the Impedance of Electrodes in Protonic Ceramic Fuel Cells International conference
Yuji Okuyama, Keita Kasuga, and Hirofumi Sumi
4th Asian Symposium on Electrochemical Impedance Spectroscopy 2024.11.25
Event date： 2024.11.25 - 2024.11.26
Language：English Presentation type：Oral presentation (general)
Awards 【 display / non-display 】
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ポスター賞
2024.9 宮崎大学
東雲遥香、奥山勇治
Award type：Award from Japanese society, conference, symposium, etc.
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Interface Ionicss/SSI seminar Award 2023 Platinum Prize
2023.8 第17回固体イオニクスセミナー
原田佳明、奥山勇治
Award type：Award from Japanese society, conference, symposium, etc.
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第60回化学関連支部合同九州大会電気化学セッション優秀研究発表賞
2023.7 電気化学会九州支部
東雲遥香、奥山勇治
Award type：Award from Japanese society, conference, symposium, etc.
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第59回化学関連支部合同九州大会電気化学セッション優秀研究発表賞
2022.7 電気化学九州支部
藤本聖、奥山勇治
Award type：Award from Japanese society, conference, symposium, etc.
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PACRIM13 FCDICポスター賞
2019.10 宮崎大学
辻川皓太
Award type：Award from international society, conference, symposium, etc. Country：Japan
Grant-in-Aid for Scientific Research 【 display / non-display 】
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Ultrafast spectroscopy of mixed electron-ion conductors for its application to fuel cells
Grant number：24K00558 2024.04 - 2027.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Authorship：Coinvestigator(s)
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Determination of defect structure in proton-conductive ceramic-electrolyte materials by light-induced pulsed ESR
Grant number：24K06923 2024.04 - 2027.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
Authorship：Coinvestigator(s)
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プロトン伝導性酸化物中の内部ポテンシャル分布制御による機能創製
Grant number：16H06124 2016.04 - 2019.03
科学研究費補助金 若手研究(A)
Authorship：Principal investigator
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酸化物の微視的欠陥制御による高プロトン伝導性材料の設計
Grant number：25709072 2013.04 - 2016.03
科学研究費補助金 若手研究(A)
本研究では化学的安定性、高い機械的強度を備えた酸化物型プロトン伝導体のプロトン伝導性を最大限まで向上させる材料設計指針を明らかにし、発電システムとして実用に耐えうるプロトン伝導体を用いてPCFC（プロトンセラミック燃料電池）を開発することを目的とする。
これまで酸化物プロトン導電体はアクセプタードーパント（低原子価カチオン）を添加した際の負の相対電荷をプロトンで補うことから添加した低原子カチオン濃度までプロトンが溶解すると考えられていた。しかしながら申請者のこれまでの研究でプロトンの最大溶解量は低原子価カチオン濃度まで達していないことが明らかになった。また、プロトンは低原子価カチオンと会合（トラップ）しており著しく水素の拡散係数を減少させていることが確認され、プロトン伝導体には大きな2つ問題点を抱えていることが明らかとなった。本研究はこの２つの問題を材料調製の観点から解決することでプロトンが溶解しやすく動きやすい酸化物すなわち最高性能を有した酸化物プロトン伝導体を設計創製し、燃料電池への応用を目指すものである。 -
不定比複合酸化物をベースとした固体電解質の高温電気化学特性とその工学的応用
Grant number：07J11286 2007.04 - 2009.03
科学研究費補助金 特別研究員推奨費
マグネシウムアルミネートスピネルの電気化学的特性(ガス濃淡電池、電気伝導度、水素溶解量、水素拡散係数)を評価しスピネルを電解質とした溶融鋳鉄用Mgセンサーの開発を試みた。
Available Technology 【 display / non-display 】
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プロトン伝導性セラミックスを用いた次世代燃料電池開発
ガス濃淡電池型水素センサの開発
機械学習を活用した新規プロトン伝導性セラミックスの探索Related fields where technical consultation is available：材料科学分野、電気化学分野、水素エネルギー関連分野、金属生産工学分野、固体イオニクス分野
Message：セラミックス合成から機能性評価、応用研究まで研究室で実施しています。
学術的な点でお困りの場合はご相談ください。