Naoki SHINYOSHI
| Department of Engineering Science | Assistant Professor |
| Cluster III (Fundamental Science and Engineering) | Assistant Professor |
Researcher Information
Research Keyword
Field Of Study
- Nanotechnology/Materials, Nanomaterials, nanoparticle synthesis
- Energy, Quantum beam science, nanoparticle synthesis
- Energy, Quantum beam science, radiation chemistry
- Nanotechnology/Materials, Structural and functional materials, electrocatalyst
- Nanotechnology/Materials, Structural and functional materials, metal oxide
Career
- May 2026 - Present
The University of Osaka, Graduate School of Engineering Department of Management of Industry and Technology, Visiting Researcher - Apr. 2026 - Present
The University of Electro-Communications, Graduate School of Informatics and Engineering Department of Engineering Science, Assistant Professor - Apr. 2025 - Mar. 2026
Japan Society for the Promotion of Science, Institute of Science Tokyo, Research Fellows - PD - Apr. 2024 - Mar. 2025
Japan Society for the Promotion of Science, Osaka University, Research Fellows - DC
Educational Background
- Apr. 2022 - Mar. 2025
Osaka University, Graduate School of Engineering, Management of Industry and Technology, Ph.D. program - Apr. 2020 - Mar. 2022
Osaka University, Graduate School of Engineering, Management of Industry and Technology, Master's program - Apr. 2016 - Mar. 2020
Osaka University, School of Engineering, Department of Sustainable Energy and Environmental Engineering
Research Activity Information
Award
- Jul. 2023
Japan Radioisotope Association
Radiation Induced Synthesis of Tin-based Nanoparticles and Investigation of the Generating Mechanism
The 27th RADIOISOTOPES Journal Incentive Award, Naoki Shinyoshi;Satoshi Seino;Naoto Uegaki;Shun Fujieda;Yuta Uetake;Takashi Nakagawa - Mar. 2023
The Ceramic Society of Japan
The 17th Material and Fabrication and Designs Study System Group of The Ceramic Society of Japan, Outstanding Material Design Award, 新��直樹;清野智史;植竹裕太;永井崇昭;門田隆二;石原顕光;中川貴 - Sep. 2022
The Ceramic Society of Japan
The Ceramic Society of Japan, The 35th Fall Meeting, Incentive Award, 新��直樹;清野智史;小野源弥;永井崇昭;門田隆二;石原顕光;植竹裕太;中川貴
Paper
- Effect of particle size on the oxygen reduction reaction activity of carbon‐supported niobium-oxide‐based nanoparticle catalysts
Naoki Shinyoshi; Satoshi Seino; Yuta Hasegawa; Yuta Uetake; Takaaki Nagai; Ryuji Monden; Akimitsu Ishihara; Takashi Nakagawa
Lead, Journal of Materials Science, 03 Feb. 2025, Peer-reviwed, Abstract:
In this study, niobium oxynitride nanoparticles were examined to determine the effect of particle size on oxygen reduction reaction (ORR) activity. To this end, catalyst precursors with niobium oxides dispersed on carbon supports were prepared using the irradiation or impregnation method. Polyacrylonitrile was added to each precursor, followed by heat treatment under an ammonia‐containing atmosphere to synthesize niobium oxynitride nanoparticles. The structures of the prepared catalysts were analyzed using transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. The results indicated that two catalysts with the same crystal phase but different particle sizes were obtained. Comparing their ORR activities revealed that the effect of particle size on ORR activity was limited. Thus, it was inferred that controlling the microelectron conduction paths can help maximize the benefits of particle size reduction. In addition, niobium oxynitride nanoparticles with different structures were obtained by varying the heat-treatment temperatures, and the ORR activity of each prepared catalyst was evaluated. These findings suggest that forming graphitized carbon residues with high electrical conductivity and controlling nitrogen-doping in the oxide nanoparticles are crucial steps for enhancing the ORR activity of oxide-based catalysts. These findings offer valuable insights for developing material design strategies to improve oxide-based catalyst performance.
Scientific journal, English - Synthesis and characterization of titanium oxynitride catalyst via direct ammonia nitridation of titanium polyacrylate for oxygen reduction reaction
Yushi Tamaki; Satoshi Seino; Naoki Shinyoshi; Yuta Uetake; Takaaki Nagai; Ryuji Monden; Akimitsu Ishihara; Takashi Nakagawa
Journal of Materials Science: Materials in Engineering, 18 Nov. 2024, Peer-reviwed, Abstract:
A titanium oxynitride catalyst for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells was synthesized through the direct ammonia nitridation of titanium complexes. Titanium polyacrylate was employed as the catalyst precursor, and the effect of the calcination temperature between 600 and 1000 °C on the catalyst structure was studied. The catalysts were characterized via X-ray diffraction, X-ray absorption spectroscopy, transmission electron microscopy, cyclic voltammetry, and powder electrical resistivity measurements. The formation of titanium oxynitride particles and deposited carbon was observed for all the samples; however, significant variations in the catalyst structure and catalytic activity were also observed. With an increase in the calcination temperature, nitridation of titanium oxynitride progressed, and the conductivity of the catalyst powder increased. The highest rest potential and ORR current density were achieved with calcination at 800 °C. Importantly, the results suggest that maintaining an optimal nitrogen doping level within the catalyst particles, along with ensuring the formation of electroconductive deposited carbon, is essential for achieving a high ORR current. This work introduces the direct ammonia nitridation of metal complexes as a promising process for designing metal oxynitride catalysts.
Scientific journal, English - Radiation-induced synthesis of carbon-supported niobium oxide nanoparticle catalysts and investigation of heat treatment conditions to improve the oxygen reduction reaction activity
Naoki Shinyoshi; Satoshi Seino; Yuta Uetake; Takaaki Nagai; Ryuji Monden; Akimitsu Ishihara; Takashi Nakagawa
Lead, Journal of the Ceramic Society of Japan, 01 Sep. 2023, Peer-reviwed, Abstract:
Carbon-supported niobium oxide nanoparticle catalysts were synthesized for the oxygen reduction reaction (ORR) in acidic media. These catalysts were prepared using a 60Co gamma-ray and heat-treated with polyacrylonitrile. Carbon black powder or multi-walled carbon nanotube (CNT) was used as the support for the niobium nanoparticle. Nb2O5 nanoparticles with low crystallinity were fine and well dispersed on the carbon support in the as-irradiated samples. The loading amount of niobium increased with the absorbed dose, which indicated that niobium nanoparticles were produced by the irradiation. The as-irradiated composite nanoparticles were heat-treated under an H2 atmosphere (5 %) or a mixed atmosphere of H2 (2 %) and O2 (0.05 %) to introduce active sites. The ORR activities were significantly enhanced by the heat treatment. Furthermore, the ORR activities were improved by using multi-walled CNT as the support.
Scientific journal, English - Radiation Induced Synthesis of Tin-based Nanoparticles and Investigation of the Generating Mechanism
Naoki Shinyoshi; Satoshi Seino; Naoto Uegaki; Shun Fujieda; Yuta Uetake; Takashi Nakagawa
Lead, RADIOISOTOPES, 15 Jul. 2022, Peer-reviwed, Abstract:
Tin nanoparticles were synthesized by chemical reactions induced by irradiation. γ-ray irradiation of aqueous solution of SnCl2 resulted in the formation of metallic Sn nanoparticles. It was indicated that Sn2+ions are reduced to zero valence by radiochemical species generated by the irradiation. On the other hand, SnO2 nanoparticles were obtained when irradiated in the presence of carbon support. Small metallic Sn nanoparticles were well dispersed on the surface of carbon support which are assumed to be easily oxidized to form SnO2 nanoparticles. It was indicated that nanoparticle synthesis techniques using radiation is applicable to form tin.
Scientific journal, Japanese
MISC
- The Effect of Particle Size on the Oxygen Reduction Reaction Activity of Carbon-Supported Niobium-Oxide-Based Nanoparticle Catalysts
Naoki Shinyoshi; Satoshi Seino; Yuta Hasegawa; Yuta Uetake; Takaaki Nagai; Ryuji Monden; Akimitsu Ishihara; Takashi Nakagawa; Yuta Nabae
Lead, One of the alternatives to platinum catalysts for the cathode of polymer electrolyte fuel cells is transition metal oxide-based catalysts, such as TiO x , ZrO x , and NbO x . Although these catalysts have been considered for their potential because of their high chemical stability under acidic conditions, their low oxygen reduction reaction (ORR) activity requires significant improvement. A contributing factor to this low activity is the poor conductivity of oxides. To improve this, it is believed necessary to control the crystal phase, the size of the oxides, and the local conduction paths near the oxide particles. Generally, it is difficult to separate and discuss these factors independently, making it unclear which factor is the most influential. In this study, niobium oxide nanoparticles with significantly different sizes were synthesized using either the irradiation method or impregnation method for the preparation of catalysts precursors, followed by heat treatment. Here, we report on the comparison of ORR activity, focusing on the differences in the size of the niobium oxide nanoparticles in the catalyst.
The irradiation method is a simple one-pot process, in which a glass vial containing ultra-pure water together with conductive carbon nanopowder and metal source (Nb 2 (C 2 O 4 ) 5 ) are irradiated with gamma-ray from a cobalt-60 source. The impregnation method places conductive carbon nanopowder and the metal source in ethanol, followed by a drying process to obtain the sample. Thus-prepared composite nanoparticles, acquired in powder form, were used as precursors. Polyacrylonitrile was added and the mixture was heat-treated in an ammonia atmosphere to prepare the catalyst. It is expected that polyacrylonitrile will be graphitized upon heat treatment, forming local conduction paths near the oxide particles.
These samples were characterized by the techniques of TEM, XRD, and LSV. When the precursor prepared by the irradiation method was heat-treated, TEM observation revealed that the Nb-based nanoparticles on the surface of the carbon support had a particle size of 7 nm (Figure 1 (a)). Following heat treatment of the impregnation-prepared precursor, the size of the Nb-based nanoparticles on the surface of the support was 13 nm (Figure 1 (b)), indicating that each method of precursor preparation successfully produced Nb-based nanoparticles of different sizes. In both cases, XRD showed diffraction patterns corresponding to niobium oxynitride. Additionally, composition ratios of niobium oxynitride determined from Vegard’s law, assuming NbO x N 1- x , were consistent regardless of the precursor preparation method.
These catalytic activities were evaluated using Linear Sweep Voltammetry in an acidic medium, based on the open circuit potential in oxygen and current density. After heat-treating the irradiation-prepared precursor, the open circuit potential and current density were slightly higher compared to the impregnation method; however, no significant difference was observed. Using a model based on several assumptions, it was suggested that the dominant factor affecting ORR activity is not the size of the metal oxide nanoparticles, but the length of the local conduction paths near the oxide nanoparticles. The present study revealed that the ORR activity in niobium oxide nanoparticle catalysts does not significantly depend on the size of the oxide nanoparticles.
[Acknowledgments]
The authors thank Koga Isotope Co. Ltd. for their cooperation with the gamma-ray irradiation. XAS experiments were performed at the NW-10A beamline of KEK under the approval of the Photon Factory Program Advisory Committee (Proposal No. 2022G074). This study was supported by JSPS KAKENHI (Grant Nos. 23K04912 and 24KJ1592).
Figure 1: TEM images of the samples obtained from heat treatment of the precursor prepared by the (a) irradiation method and (b) impregnation method.
Figure 1
, The Electrochemical Society, 24 Nov. 2025, ECS Meeting Abstracts, MA2025-02, 38, 1770-1770, Peer-reviwed, Summary international conference, 2151-2043
Lectures, oral presentations, etc.
- The Effect of Particle Size on the Oxygen Reduction Reaction Activity of Carbon-Supported Niobium-Oxide-Based Nanoparticle Catalysts
N. Shinyoshi; S. Seino; Y. Hasegawa; Y. Uetake; T. Nagai; R. Monden; A. Ishihara; T. Nakagawa; Y. Nabae
248th ECS Meeting, Peer-reviewed
12 Oct. 2025- 16 Oct. 2025 - ニオブ高分子錯体への放射線照射によるニオブ/カーボン複合ナノ粒子の合成
新��直樹; 清野智史; 山本春也; 植竹裕太; 門田隆二; 石原顕光; 中川貴
第67回放射線化学討論会
06 Sep. 2024- 07 Sep. 2024 - 高分子錯体を原料とした金属酸化物ナノ粒子の放射線法による合成
新��直樹; 清野智史; 長谷川優太; 植竹裕太; 永井崇昭; 門田隆二; 石原顕光; 中川貴
第19回日本セラミックス協会マテリアル・ファブリケーション・デザイン研究会
27 Mar. 2024- 29 Mar. 2024 - 高分子錯体を原料としたニオブ酸化物ナノ粒子の放射線法による合成
新��直樹; 清野智史; 長谷川優太; 永井崇昭; 門田隆二; 石原顕光; 中川貴
第66回放射線化学討論会
28 Sep. 2023- 29 Sep. 2023 - カーボン担持ニオブ酸化物ナノ粒子触媒の合成におけるポリアクリロニトリル添加の影響
新��直樹; 清野智史; 植竹裕太; 永井崇昭; 門田隆二; 石原顕光; 中川貴
第17回日本セラミックス協会マテリアル・ファブリケーション・デザイン研究会
28 Mar. 2023- 29 Mar. 2023 - カーボン担持ニオブ酸化物ナノ粒子触媒の合成におけるポリアクリロニトリル添加の影響
新��直樹
第17回日本セラミックス協会マテリアル・ファブリケーション・デザイン研究会, Invited
28 Mar. 2023- 29 Mar. 2023 - 放射線を用いたMOx/CNTナノ粒子触媒の合成 (M = Nb, Zr)
新��直樹; 清野智史; 長谷川優太; 植竹裕太; 永井崇昭; 門田隆二; 石原顕光; 中川貴
日本セラミックス協会 2023年年会
08 Mar. 2023- 10 Mar. 2023 - Radiation Induced Synthesis of Niobium Oxide Nanoparticle Catalyst for Polymer Electrolyte Fuel Cells: Effect of Carbon Support on Catalytic Activity
Y. Hasegawa; N. Shinyoshi; G. Ono; S. Seino; T. Nagai; A. Ishihara; T. Nakagawa
1st STACY Young Generation Symposium
14 Dec. 2022- 17 Dec. 2022 - PEFC用カソード触媒のための非白金系金属酸化物ナノ粒子の合成およびORR活性向上に向けた熱処理条件の検討
新��直樹; 清野智史; 小野源弥; 永井崇昭; 門田隆二; 石原顕光; 植竹裕太; 中川貴
日本セラミックス協会 第35回秋季シンポジウム
14 Sep. 2022- 16 Sep. 2022 - 放射線を用いた Sn 系ナノ粒子の合成
新��直樹; 清野智史; 上垣直人; 中川貴
第64回放射線化学討論会
06 Sep. 2021- 08 Sep. 2021 - 放射線を用いたカーボン担持SnO2ナノ粒子の合成
新��直樹; 清野智史; 上垣直人; 藤枝俊; 中川貴; 山本孝夫
ナノ学会 第19回大会
20 May 2021- 22 May 2021 - 放射線を用いたカーボン担持SnO2ナノ粒子の合成
新��直樹; 清野智史; 上垣直人; 藤枝俊; 中川貴; 山本孝夫
日本化学会 第101春季年会
19 Mar. 2021- 22 Mar. 2021
Courses
Research Themes
- 高分子錯体を原料とする非白金系酸素還元反応触媒の大線量放射線を用いた合成
新��直樹
日本学術振興会, 科学研究費助成事業, 東京科学大学, 特別研究員奨励費, Principal investigator, 25KJ0128
Apr. 2025 - Mar. 2028 - Radiation-induced Synthesis of Carbon-supported Metal Oxide Nanoparticle Catalysts
新��直樹
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Osaka University, Grant-in-Aid for JSPS Fellows, Principal investigator, 24KJ1592
Apr. 2024 - Mar. 2026
