Updated on 2025/07/25

Information

 

写真a

 
HOJO HAJIME
 
Organization
Faculty of Engineering Sciences Department of Advanced Materials Science and Engineering Associate Professor
Interdisciplinary Graduate School of Engineering Sciences Department of Interdisciplinary Engineering Sciences（Concurrent）
School of Engineering （Concurrent）
Title
Associate Professor
Contact information
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Tel
0925837526
Profile
機能性酸化物材料の合成と、第一原理計算、透過型電子顕微鏡法を駆使したその機能発現機構の解明を目指した研究を行っています。
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Research Areas

  • Nanotechnology/Materials / Inorganic compounds and inorganic materials chemistry

  • Nanotechnology/Materials / Thin film/surface and interfacial physical properties

  • Nanotechnology/Materials / Inorganic materials and properties

Degree

  • Ph.D.

Research History

  • Tokyo Institute of Technology   

Education

  • Kyoto University   大学院工学研究科   材料化学専攻

    2005.4 - 2008.3

  • Kyoto University   大学院工学研究科   材料化学専攻

    2003.4 - 2005.3

  • Kyoto University   工学部   工業化学科

    1999.4 - 2003.3

Research Interests・Research Keywords

  • Research theme： functional transition metal oxide thin films

    Keyword： piezoelectric materials, multiferroic materials

    Research period： 2011.4

  • Research theme： Transmission electron microscopy analysis of functional oxides

    Keyword： Crystal structure, electronic structure

    Research period： 2008.4

Awards

  • 文部科学省ナノテクノロジープラットフォーム　令和元年度　秀でた利用成果　優秀賞

    2020.1   文部科学省ナノテクプラットフォーム、国立研究開発法人物質・材料研究機構  

  • ATI研究奨励賞

    2019.5   公益財団法人新世代研究所   室温で強誘電性と弱強磁性が共存したマルチフェロイック物質であるBiFe1-xCoxO3薄膜について、室温で電場による磁化反転が起こることを実証した。

  • フロンティア材料研究所学術賞　研究奨励部門

    2018.9   東京工業大学　科学技術創成研究院 フロンティア材料研究所   室温で強誘電性と弱強磁性が共存したBiFe1-xCoxO3薄膜の合成に成功し、強誘電性秩序と強磁性秩序の間に相関が存在することを明らかにした。

  • International Conference on Ferrite (ICF) 11, Young Researcher Award

    2013.5  

Papers

  • Lattice-Plane-Dependent Distribution of Ce3+ at Pt and CeO2 Interfaces for Pt/CeO2 Catalysts Reviewed International journal

    Hajime Hojo, Minori Nakashima, Satoru Yoshizaki, Hisahiro Einaga

    ACS Nano   18 ( 6 )   4775 - 4782   2023.12

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    Language：English   Publishing type：Research paper (scientific journal)  

    The interaction between a metal and a support, which is known as the metal−support interaction, often plays a determining role in the catalytic properties of supported metal catalysts. Herein, we have developed model Pt/CeO2 catalysts, which enabled us to investigate the interface atomic and electronic structures between Pt and the {001}, {011}, and {111} planes of CeO2 using scanning transmission electron microscopy and electron energy-loss spectroscopy. We found that the number of Ce3+ ions around the Pt nanoparticles followed the order {001} > {011} > {111}, which was the opposite order of the generally accepted stability of low index surfaces of CeO2. Systematic first-principles calculations revealed that the presence of Pt nanoparticles facilitated the formation of oxygen vacancies and that the appearance of the Ptδ+ state was preferred when Pt nanoparticles were in contact with CeO2 {001} planes due to direct charge transfer from Pt to CeO2. These results provide important insights into the nature of the metal−support interaction for a comprehensive understanding of the properties of supported metal catalysts.

    DOI： https://doi.org/10.1021/acsnano.3c09092

  • Reduction Mechanism for CeO2 Revealed by Direct Observation of the Oxygen Vacancy Distribution in Shape-Controlled CeO2 Invited Reviewed International journal

    Hajime Hojo, Kazuki Hirota, So Ito, Hisahiro Einaga

    Advanced Materials Interfaces   10   2201954   2022.12

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    Language：English   Publishing type：Research paper (scientific journal)  

    Repository Public URL： https://hdl.handle.net/2324/7181933

  • Direct identification of the charge state in a single platinum nanoparticle on titanium oxide Invited Reviewed International journal

    Ryotaro Aso, Hajime Hojo, Yoshio Takahashi, Tetsuya Akashi, Yoshihiro Midoh, Fumiaki Ichihashi, Hiroshi Nakajima, Takehiro Tamaoka, Kunio Yubuta, Hiroshi Nakanishi, Hisahiro Einaga, Toshiaki Tanigaki, Hiroyuki Shinada, Yasukazu Murakami

    Science   378   202 - 206   2022.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    A goal in the characterization of supported metal catalysts is to achieve particle-by-particle analysis of the charge state strongly correlated with the catalytic activity. Here, we demonstrate the direct identification of the charge state of individual platinum nanoparticles (NPs) supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. Sophisticated phase-shift analysis for the part of the NPs protruding into the vacuum visualized slight potential changes around individual platinum NPs. The analysis revealed the number (only one to six electrons) and sense (positive or negative) of the charge per platinum NP. The underlying mechanism of platinum charging is explained by the work function differences between platinum and titanium dioxide (depending on the orientation relationship and lattice distortion) and by first-principles calculations in terms of the charge transfer processes.

    Repository Public URL： https://hdl.handle.net/2324/7173150

  • Atomic and Electronic Structure of Pt/TiO2 Catalysts and Their Relationship to Catalytic Activity Invited Reviewed International journal

    Hajime Hojo, Miki Gondo, Satoru Yoshizaki, and Hisahiro Einaga

    Nano Letters   22 ( 1 )   145 - 150   2021.12

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    Language：English   Publishing type：Research paper (scientific journal)  

    Understanding the nature of the interaction between a metal and support, which is known as the metal−support interaction, in supported metal catalysts is crucial to design catalysts with desired properties. Here, we have
    developed model Pt/TiO2 catalysts based on the deposition of colloidal Pt nanoparticles and studied their atomic and electronic structures before and after a postdeposition treatment that induces catalytic activity using aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles calculations. Direct contact between Pt nanoparticles and TiO2 is realized after the postdeposition treatment, which is accompanied by the formation
    of a Ti3+ state on the TiO2 surface close to the Pt nanoparticles and a Ptδ+ state on the Pt nanoparticles. The origin of these two states and their effect on the catalytic properties are discussed. These findings pave the way for a comprehensive understanding of metal−support interactions in supported metal catalysts.

  • Development of Bismuth Ferrite as a Piezoelectric and Multiferroic Material by Cobalt Substitution Invited Reviewed International journal

    #Hajime Hojo, @Kengo Oka, @Keisuke Shimizu, @Hajime Yamamoto, @Ryo Kawabe, and @Masaki Azuma

    Advanced Materials   30 ( 33 )   1705665-1 - 1705665-15   2018.8

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    Language：Japanese   Publishing type：Research paper (scientific journal)  

    室温で強磁性と強誘電性が共存したマルチフェロイック物質であるBiFe1-xCoxO3について、その圧電特性とマルチフェロイック特性と結晶構造との相関を明らかにした一連の研究の総説

    DOI： 10.1002/adma.201705665

  • Ferromagnetism at Room Temperature Induced by Spin Structure Change in BiFe1−xCoxO3 Thin Films Reviewed

    Hajime Hojo, Ryo Kawabe, Keisuke Shimizu, Hajime Yamamoto, Ko Mibu, Kartik Samanta, Tanusri Saha-Dasgupta, Masaki Azuma

    Advanced Materials   29 ( 9 )   2017.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1002/adma.201603131

  • Enhanced Piezoelectric Response due to Polarization Rotation in Cobalt-Substituted BiFeO3Epitaxial Thin Films Reviewed

    Keisuke Shimizu, Hajime Hojo, Yuichi Ikuhara, Masaki Azuma

    Advanced Materials   28 ( 39 )   8639 - 8644   2016.1

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1002/adma.201602450

  • Atomic structure of a CeO2 grain boundary: The role of oxygen vacancies Reviewed

    Hajime Hojo, Teruyasu Mizoguchi, Hiromichi Ohta, Scott D. Findlay, Naoya Shibata, Takahisa Yamamoto, Yuichi Ikuhara

    Nano Letters   10 ( 11 )   4668 - 4672   2010.11

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/nl1029336

  • Room-temperature ferrimagnetic semiconductor 0.6FeTiO3 ̇ 0.4Fe2O3 solid solution thin films Reviewed

    Hajime Hojo, Koji Fujita, Katsuhisa Tanaka, Kazuyuki Hirao

    Applied Physics Letters   89 ( 14 )   2006.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.2357547

  • Direct Visualization of Surface Structure and Charge States of Ceria-Supported Gold Catalysts Under Redox Conditions

    Aso, R; Tamaoka, T; Yoshida, H; Hojo, H; Sano, H; Midoh, Y; Einaga, H; Tanigaki, T; Murakami, Y

    ADVANCED SCIENCE   e08554   2025.7   （ eISSN:2198-3844 ）

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    Language：English   Publisher：Advanced Science  

    Observing the surface structure and charge dynamics of catalysts during catalytic reactions is crucial for elucidating reaction mechanisms. However, nanoscale characterization of the catalyst structure and charge states in the presence of reactive gases presents experimental challenges. Here, the structures and charge states of a gold nanoparticle (NP) are directly visualized on ceria during redox cycles using electron holography, a method related to transmission electron microscopy. The introduction of oxidizing O<inf>2</inf> gas to the microscope led to structural changes on the NP surface and decrease the intrinsic negative charge of the NP. Conversely, under reducing H<inf>2</inf> gas, the surface structure and charge state of the NP remained almost unchanged compared to those in vacuum. Systematic analysis revealed that the injection and removal of O<inf>2</inf> gas caused reversible changes in the charge state of the NP within the range of a few electrons. The effect of O<inf>2</inf> gas on charging of the NP is confirmed by first-principles calculations. These findings demonstrate the potential of electron holography in gas environments for advancing the understanding the reaction mechanisms on heterogeneous catalysts.

    DOI： 10.1002/advs.202508554

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    PubMed

  • Ag plasmon adjusted single crystal Cu2O nanoreactor array with ordered charge transport and light multiplication effect for high photocatalytic conversion of CO2

    Xu, MY; Yan, CL; Chang, BQ; Hou, YC; Wang, HQ; Song, XH; Zhou, WQ; Liu, X; Yan, Y; Zhang, JS; Yang, YY; Einaga, H; Hojo, H; Huo, PW

    NANO ENERGY   139   2025.6   （ ISSN:2211-2855 eISSN:2211-3282 ）

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    Publisher：Nano Energy  

    Local surface plasmon resonance (LSPR) is introduced into traditional photocatalytic systems, which has become a research focus. However, there is still a huge gap in the research of LSPR effect, especially the requirement of ideal plasma carrier has not been fully elaborated and planned. Here, a single crystal Cu<inf>2</inf>O nanoreactor (Cu<inf>2</inf>O-V) was synthesized with surface modified silver nanoparticles as an optical antenna for CO<inf>2</inf> conversion. The precisely designed Cu<inf>2</inf>O single crystal structure has a highly ordered atomic arrangement and fewer grain boundary defects, which provides a high-speed electron transport path and greatly improves the stability of Cu<sup>+</sup>. Meanwhile, the vesicle structure and thin shell array formation of Cu<inf>2</inf>O-V form a "double light trap", showing prominent LSPR amplification effect. This allows the catalyst to be uniformly immersed in the local electromagnetic field, further increasing the rate of carrier generation and transfer. Finally, under the synergistic action of “double light trap” and LSPR, Ag<inf>5 %</inf>-Cu<inf>2</inf>O-V shows first-class performance and excellent stability. A small amount of C<inf>2</inf>H<inf>4</inf> was also detected. This study reveals the effect of a single crystal Cu<inf>2</inf>O catalyst characterized by a high-speed electron transport channel and vesicle array structure combined with LSPR on the photoreactivity.

    DOI： 10.1016/j.nanoen.2025.110930

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  • Kinetic advantages of microwave activation in the dry reforming of methane: insights gained by SSITKA

    Hamashima, T; Palomo, J; Coppens, M; Hojo, H; Einaga, H; Urakawa, A

    INDUSTRIAL CHEMISTRY & MATERIALS   2025.6   （ ISSN:2755-2608 eISSN:2755-2500 ）

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  • Nanosecond electric pulse-induced ultrafast piezoelectric responses in Co<SUP>3+</SUP> substituted BiFeO<sub>3</sub> epitaxial thin films

    Unithrattil, S; Min, T; Anoop, G; Lee, JY; Kim, TY; Samanta, S; Qi, YB; Zhang, JH; Hwang, SH; Lee, HJ; Guo, K; Lee, SY; Imai, Y; Sakata, O; Shimizu, K; Shigematsu, K; Hojo, H; Yao, K; Azuma, M; Lee, J; Rappe, AM; Jo, JY

    CURRENT APPLIED PHYSICS   70   76 - 80   2025.2   （ ISSN:1567-1739 eISSN:1878-1675 ）

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    Publisher：Current Applied Physics  

    Understanding the ultra-fast dynamics of ferroelectric materials is essential for advancing the development of next-generation high speed electronic and photonic devices. Here, the ultrafast piezoelectric response of cobalt-substituted BiFeO<inf>3</inf> (BiFe<inf>1-x</inf>Co<inf>x</inf>O<inf>3</inf>) with x = 0.15, consisting of morphotropic phase boundary of monoclinic M<inf>C</inf> and M<inf>A</inf> –type phases is investigated. The real-time piezoelectric response in (001)-oriented BiFe<inf>0.85</inf>Co<inf>0.15</inf>O<inf>3</inf> (BFCO) epitaxial thin film was monitored using the time-resolved X-ray microdiffraction technique under an applied electric field with pulse widths 70 ns and 100 ns. The BFCO thin film yielded a high piezoelectric strain of approximately 0.53 % along [001] direction, with a giant c/a ratio (∼1.26) at an electric field of 1.3 MV/cm and a pulse width of 100 ns, with a piezoelectric coefficient (d<inf>33</inf>) of 40 pm/V. This finding is an important step towards the development of a high performance lead-free piezoelectric material for ultrafast operations in advanced technological applications.

    DOI： 10.1016/j.cap.2024.11.012

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  • Microwave-Assisted Heating for Dehydration of Ethanol to Ethylene Using HPW/SBA-15

    Ni, ZT; Hojo, H; Einaga, H

    INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH   64 ( 5 )   2686 - 2695   2025.1   （ ISSN:0888-5885 eISSN:1520-5045 ）

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    Publisher：Industrial and Engineering Chemistry Research  

    Catalytic dehydration of bioethanol using tungsten polyoxometalate (POM) clusters is a viable method for the sustainable production of ethylene, a valuable industrial chemical. The reaction process of ethanol dehydration on mesoporous-silica-SBA-15 (SBA-15)-supported heteropolyacids (HPAs) involves complex parallel-consecutive pathways, which differ from those involved in pure HPAs systems. Notably, the reaction progresses from the formation of diethyl ether at lower temperatures to the complete generation of ethylene at higher temperatures. To conserve energy, achieving high selectivity for ethylene at lower temperatures is crucial. In this study, we impregnated 12-tungstophosphoric acid into an SBA-15 catalyst, followed by microwave-assisted heating to obtain a catalyst that facilitates the dehydration of ethanol to ethylene. Experimental findings revealed that this catalytic technique achieves a reaction at lower temperatures than conventional thermal catalysis, exhibiting conversion rates and selectivity values exceeding 99%. Additionally, the influence of the substrate on the entire reaction process was elucidated by clarifying the reaction pathways using theoretical calculations.

    DOI： 10.1021/acs.iecr.4c04420

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  • Comparative Evaluation of Microwave Heating Performance across Structurally Diverse Tungsten Oxides

    Ni, ZT; Hojo, H; Einaga, H

    JOURNAL OF PHYSICAL CHEMISTRY C   128 ( 33 )   13807 - 13815   2024.8   （ ISSN:1932-7447 eISSN:1932-7455 ）

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    Publisher：Journal of Physical Chemistry C  

    Microwave heating is an effective method for efficiently heating a target material, allowing the chemical reaction processes to proceed quickly. In catalytic reactions under microwave irradiation, it is essential to understand the relationship between the structure and physical properties of the material to be used as a catalyst and microwave heating. In this study, we focused on tungsten oxides, which absorb microwaves and convert them into heat, and we compared the microwave heating properties of tungsten oxides with different structures. The heating properties of tungsten oxides under microwave irradiation are highly dependent on their morphologies. WO<inf>3</inf> nanoflakes with a monoclinic phase structure have a more rapidly heated surface than tungsten oxides with other morphologies. The heating characteristics of each tungsten oxide were consistent with the dielectric loss factor obtained by the perturbation method. Finite element analysis was used to gain a better understanding of the thermal distribution of materials during microwave irradiation.

    DOI： 10.1021/acs.jpcc.4c02936

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  • Mechanism of intermetallic charge transfer and bond disproportionation in BiNiO3 and PbNiO3 revealed by hard x-ray photoemission spectroscopy

    Yamaguchi, T; Furo, M; Sakai, Y; Nishikubo, T; Hojo, H; Azuma, M; Oka, K; Mori, D; Inaguma, Y; Mizumaki, M; Yamamoto, K; Kunes, J; Mizokawa, T; Hariki, A

    PHYSICAL REVIEW B   109 ( 20 )   2024.5   （ ISSN:2469-9950 eISSN:2469-9969 ）

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    Publisher：Physical Review B  

    Perovskites with Bi or Pb on the A site host a number of interesting and yet to be understood phenomena such as negative thermal expansion in BiNiO3. We employ hard x-ray photoemission spectroscopy of Ni 2p core level as well as valence band to probe the electronic structure of BiNiO3 and PbNiO3. The experimental results supported by theoretical calculations using dynamical mean-field theory reveal essentially identical electronic structure of the Ni-O subsystem typical of Ni2+ charge-transfer insulators. The two materials are distinguished by filling of the Bi(Pb)-O antibonding states in the vicinity of the Fermi level, which is responsible for the Bi disproportionation in BiNiO3 at ambient pressure and absence of similar behavior in PbNiO3. The present experiments provide evidence for this conclusion by revealing the presence/absence of Bi/Pb 6s states at the top of the valence band in the two materials.

    DOI： 10.1103/PhysRevB.109.205131

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  • Microwave-assisted CO oxidation over LaNiO3 and Ce-promoted LaNiO3

    Hamashima, T; Sugiyama, T; Hojo, H; Einaga, H

    JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS   158   2024.5   （ ISSN:1876-1070 eISSN:1876-1089 ）

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    Publisher：Journal of the Taiwan Institute of Chemical Engineers  

    Microwave-assisted catalytic reactions have been investigated for energy-efficient chemical processes. However, catalysts with comparatively high heating properties, activities, and economics have been developed with limited success. In this study, we investigated the catalytic properties of Ce addition to LaNiO<inf>3</inf> catalyst, which has high CO oxidation activity and high microwave heating properties. Ce-added catalysts exhibited high heating properties under microwave heating. Increasing the Ce content in the catalyst enhanced the dielectric loss factor, the ability to absorb microwaves and convert them to heat, and improved the microwave heating properties of the catalyst. The catalytic activity toward CO oxidation over Ce-added catalysts decreased in the order of La<inf>0.8</inf>Ce<inf>0.2</inf>NiO<inf>3</inf> > La<inf>0.9</inf>Ce<inf>0.1</inf>NiO<inf>3</inf> > LaNiO<inf>3</inf> at all oxygen partial pressures when compared to the same microwave power. To clarify the role of Ce addition, temperature programmed reduction (TPR) by H<inf>2</inf> <inf>,</inf> CO, and XAFS measurements were performed. TPR results suggested that Ce promotes oxygen mobility and then affects both CO oxidation and microwave heating properties.

    DOI： 10.1016/j.jtice.2023.105041

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  • Enhanced Benzene Oxidation of Sintered Pd/γ-Al2O3 Catalysts by SO2 Treatment Reviewed International journal

    Saki Shigenobu, Takeharu Sugiyama, Hajime Hojo, Hisahiro Einaga

    Catalysis Letters   153 ( 11 )   3423 - 3432   2023.11

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    Language：English   Publishing type：Research paper (scientific journal)  

  • Confirmation of ferroelectricity, piezoelectricity, and crystal structure of the electronic dielectric TmFe2O4 Reviewed International journal

    Shinya Konishi, Daisuke Urushihara, Tatsuya Hayakawa, Koichiro Fukuda, Toru Asaka, Koji Ishii, Noriaki Naoda, Mari Okada, Hirofumi Akamatsu, Hajime Hojo, Masaki Azuma, Katsuhisa Tanaka

    Physical Review B   108 ( 1 )   014105   2023.7

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    Language：English   Publishing type：Research paper (scientific journal)  

  • Catalytic properties of LaNiO3 and Mn-modified LaNiO3 catalysts for oxidation of CO and benzene Invited Reviewed International journal

    Hajime Hojo, Yuka Inohara, Ryo Ichitsubo, Hisahiro Einaga

    Catalysis Today   410   127 - 134   2023.6

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    Language：English   Publishing type：Research paper (scientific journal)  

    Repository Public URL： https://hdl.handle.net/2324/7181937

  • Effect of dislocations and impurities on carrier transport in α-Ga2O3 on m-plane sapphire substrate Reviewed International journal

    Hitoshi Takane, Hirokazu Izumi, Hajime Hojo, Takeru Wakamatsu, Katsuhisa Tanaka, Kentaro Kaneko

    Journal of Materials Research   38 ( 10 )   2645 - 2654   2023.5

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  • Insights into the effect of cobalt substitution into copper-manganese oxides on enhanced benzene oxidation activity Invited Reviewed International journal

    Siyu Ding, Chen Zhu, Hajime Hojo, Hisahiro Einaga

    Applied Catalysis B: Environmental   323   122099   2023.4

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    Language：English   Publishing type：Research paper (scientific journal)  

  • Insights into the effect of cobalt substitution into copper-manganese oxides on enhanced benzene oxidation activity

    Ding, SY; Zhu, C; Hojo, H; Einaga, H

    APPLIED CATALYSIS B-ENVIRONMENT AND ENERGY   323   2023.4   （ ISSN:0926-3373 eISSN:1873-3883 ）

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    Publisher：Applied Catalysis B Environmental  

    Co-substituted Cu-Mn spinel oxides were synthesized, characterized, and catalytic performance for benzene oxidation was evaluated. Spinel phases, and the substitution of Mn sites by Co were confirmed for the ternary oxides. Co<inf>0.2</inf>Cu<inf>0.8</inf>MnO<inf>y</inf> showed the highest activities with the lowest apparent activation energy among the ternary oxides. The improved catalytic properties due to Co substitution are attributed to more activated lattice oxygen, stronger adsorption of benzene, and a larger specific surface area. Density functional theory simulations also revealed that the Co substitution enhanced the reactivity of the lattice oxygen. Adsorbed and activated benzene reacted with lattice oxygen to form abundant oxygen defects, which promoted O<inf>2</inf> adsorption and dissociation, contributing to enhanced catalytic activity. The effect of water vapor on the catalytic benzene oxidation was also clarified.

    DOI： 10.1016/j.apcatb.2022.122099

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  • Reduction Mechanism for CeO_2 Revealed by Direct Observation of the Oxygen Vacancy Distribution in Shape-Controlled CeO_2

    Hojo Hajime, Hirota Kazuki, Ito So, Einaga Hisahiro

    Advanced Materials Interfaces   10 ( 6 )   2201954   2023.2   （ ISSN:21967350 eISSN:21967350 ）

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    Language：English   Publisher：Wiley  

    CeO_2 and CeO_2-based materials are widely used as catalysts and catalyst supports for a variety of chemical reactions. The ability to form oxygen vacancies plays an important role in the catalytic activities in these materials. Therefore, revealing the reduction mechanism for CeO_2 is crucial to uderstanding the catalytic activities. In this study, shape-controlled CeO_2 nanoparticles are fabricated and the distribution of surface oxygen vacancies on the (100) and (111) surfaces is systematically studied using scanning transmission electron microscopy and electron energy-loss spectroscopy and the response to H_2 reduction treatment. It is successfully demonstrated that both catalytic activities and the ability to form oxygen vacancies are strongly dependent on the type of lattice planes. Moreover, the present results provide important insights into the reduction mechanism for CeO_2, in which bulk oxygen instead of the widely believed surface capping oxygen makes no small contribution to the initial reduction step.

    DOI： 10.1002/admi.202201954

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    CiNii Research

  • Catalytic properties of LaNiO3 and Mn-modified LaNiO3 catalysts for oxidation of CO and benzene

    Hojo, H; Inohara, Y; Ichitsubo, R; Einaga, H

    CATALYSIS TODAY   410   127 - 134   2023.2   （ ISSN:0920-5861 eISSN:1873-4308 ）

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    Publisher：Catalysis Today  

    ABO<inf>3</inf>-type perovskite oxides containing transition metals at the B site are effective catalysts for oxidation reactions. In this study, LaNiO<inf>3</inf> was prepared by the hydrolysis-precipitation method, and LaNiO<inf>3</inf> was modified with Mn by the impregnation method. LaNiO<inf>3</inf> showed higher CO oxidation activity than LaCoO<inf>3</inf>, LaMnO<inf>3</inf>, and LaFeO<inf>3</inf>. The high activity of LaNiO<inf>3</inf> was attributed to the reactivity of the lattice oxygen in LaNiO<inf>3</inf>, as confirmed by temperature-programmed reduction by H<inf>2</inf> (H<inf>2</inf>-TPR) and CO-TPR studies. The Mn-modified LaNiO<inf>3</inf> exhibited higher activity for benzene oxidation than LaNiO<inf>3</inf>. The CO oxidation properties of the Mn-modified LaNiO<inf>3</inf> catalysts correlated with their H<inf>2</inf>-reduction properties, whereas benzene oxidation properties were improved by the increasing amount of Mn on the catalyst surface.

    DOI： 10.1016/j.cattod.2022.07.002

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  • Enhanced Photocatalytic Benzene Oxidation to Phenol over Monoclinic WO<sub>3</sub> Nanorods under Visible Light

    Wang, ZR; Zhu, C; Ni, ZT; Hojo, H; Einaga, H

    ACS CATALYSIS   12 ( 24 )   14976 - 14989   2022.12   （ ISSN:2155-5435 ）

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    Publisher：ACS Catalysis  

    The photocatalytic oxidation of benzene to phenol driven by visible light (λ > 420 nm) at room temperature and under ambient pressure is a promising process. In particular, the application of heterogeneous catalysts to benzene photooxidation, where the catalyst and product are easily separated, facilitates the construction of practical processes. Here, we report that a Pt-loaded 1D monoclinic WO<inf>3</inf>nanorod (Pt/m-WNR) exhibited higher activities than other Pt/WO<inf>3</inf>catalysts with different crystal structures and morphologies in water under ambient conditions and visible light. Pt/m-WNR showed high stability in repeated reactions. Furthermore, other typical photocatalysts (TiO<inf>2</inf>, Bi<inf>2</inf>WO<inf>6</inf>, Bi<inf>2</inf>MoO<inf>6</inf>, BiOBr, and C<inf>3</inf>N<inf>4</inf>) showed negligible phenol formation using Pt as a cocatalyst. Both experimental results and density functional theory calculations show that the specific performance of Pt/m-WNR is due to the efficient reduction of O<inf>2</inf>to produce hydroxyl radicals via H<inf>2</inf>O<inf>2</inf>as an intermediate. Notably, m-WNR shows much higher phenol formation than h-WNR, although h-WNR has a higher surface area. The higher activity of m-WNR may be due to its lower work function to provide electrons for O<inf>2</inf>reduction. A lower work function will favorably form a higher Schottky barrier with Pt nanoparticles to suppress the recombination of photogenerated charge carriers. The effect of the Schottky barrier is further confirmed by different activities using various metal particles as cocatalysts.

    DOI： 10.1021/acscatal.2c03832

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  • Catalytic Oxidation of CO to CO2 over CeO2-Supported Pd-Cu Catalysts under Dilute O2 Conditions

    Shigenobu, S; Hojo, H; Einaga, H

    INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH   61 ( 43 )   15856 - 15865   2022.10   （ ISSN:0888-5885 ）

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    Publisher：Industrial and Engineering Chemistry Research  

    Catalytic CO oxidation processes under dilute oxygen conditions are key industrial and environmental processes. CeO<inf>2</inf>-supported Pd and Pd-Cu catalysts (Pd/CeO<inf>2</inf>and Pd-Cu/CeO<inf>2</inf>) were prepared by impregnation, and the effect of Cu addition on the catalytic properties of CO oxidation was investigated under CO/O<inf>2</inf>stoichiometric conditions. The activity of Pd/CeO<inf>2</inf>was superior to that of Pd/TiO<inf>2</inf>and Pd/Al<inf>2</inf>O<inf>3</inf>at low temperatures. The Cu addition to Pd/CeO<inf>2</inf>with a Cu/Pd molar ratio of approximately 1-5 enhanced the CO oxidation activity. Small PdO particles were distributed over the CeO<inf>2</inf>surfaces, and Cu addition decreased the size of the Pd particles on the CeO<inf>2</inf>and increased the fraction of highly reactive Pd sites. As the Cu/Pd mole fraction in the Pd-Cu/CeO<inf>2</inf>catalyst increased to 10, the PdO on CeO<inf>2</inf>agglomerated significantly, and the CO oxidation activity decreased.

    DOI： 10.1021/acs.iecr.2c02199

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  • Direct identification of the charge state in a single platinum nanoparticle on titanium oxide

    Aso, R; Hojo, H; Takahashi, Y; Akashi, T; Midoh, Y; Ichihashi, F; Nakajima, H; Tamaoka, T; Yubuta, K; Nakanishi, H; Einaga, H; Tanigaki, T; Shinada, H; Murakami, Y

    SCIENCE   378 ( 6616 )   202 - 206   2022.10   （ ISSN:0036-8075 eISSN:1095-9203 ）

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    A goal in the characterization of supported metal catalysts is to achieve particle-by-particle analysis of the charge state strongly correlated with the catalytic activity. Here, we demonstrate the direct identification of the charge state of individual platinum nanoparticles (NPs) supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. Sophisticated phase-shift analysis for the part of the NPs protruding into the vacuum visualized slight potential changes around individual platinum NPs. The analysis revealed the number (only one to six electrons) and sense (positive or negative) of the charge per platinum NP. The underlying mechanism of platinum charging is explained by the work function differences between platinum and titanium dioxide (depending on the orientation relationship and lattice distortion) and by first-principles calculations in terms of the charge transfer processes.

    DOI： 10.1126/science.abq5868

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  • Catalytic Oxidation of CO to CO2 over CeO2-Supported Pd-Cu Catalysts under Dilute O2 Conditions Invited Reviewed International journal

    Saki Shigenobu, Hajime Hojo, Hisahiro Einaga

    Industrial & Engineering Chemistry Research   61   15856   2022.10

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    Repository Public URL： https://hdl.handle.net/2324/7181932

  • Microwave-assisted removal of benzene with high efficiency on cobalt modified copper-manganese spinel oxides

    Ding, SY; Hojo, H; Einaga, H

    JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING   10 ( 5 )   2022.10   （ ISSN:2213-2929 eISSN:2213-3437 ）

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    Publisher：Journal of Environmental Chemical Engineering  

    Microwave-assisted process has been demonstrated to have immense potential for promoting chemical reactions and reducing energy consumption. In this study, catalytic oxidation of benzene was carried out over Co-Cu-Mn mixed oxides (CoxMn1-xCuOy) under microwave irradiation. The spinel-type mixed oxides were mainly formed for the Co-Cu-Mn mixed oxides with different Co/Mn ratios. The substitution of Mn sites by Co was confirmed by Fourier and Wavelet transformed extended x-ray absorption fine structure spectra. As the Co/Mn ratio increased, the heating characteristics of the catalysts under microwave irradiation monotonically improved. The benzene oxidation activity increased on the Co/Mn ratio of 2/3 due to the enhanced specific surface area, benzene adsorption properties, and lattice-oxygen reactivity. Microwave inducing significantly lowered the reaction temperature required for benzene oxidation. Co0.4Mn0.6CuOy completely oxidized benzene at a relatively low microwave power compared to pristine Cu-Mn oxides. The Co-Cu-Mn oxides showed high activity and stability for benzene oxidation even under humid conditions. Combining pre-adsorption and thermal oxidation processes on Co0.4Mn0.6CuOy improved the low concentration of benzene oxidation efficiency by rapid microwave heating. The compound of Co0.4Mn0.6CuOy and Co0.8Mn0.2CuOy mixed at 3:1 showed even higher activity than Co0.4Mn0.6CuOy.

    DOI： 10.1016/j.jece.2022.108212

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  • Insights into the Hydrogenolysis Mechanism of Diphenyl Ether over Cl-Modified Pt/γ-Al2O3 Catalysts by Experimental and Theoretical Studies Invited Reviewed International journal

    Chen Zhu, Hajime Hojo, Hisahiro Einaga

    ACS Sustainable Chemistry & Engineering   10   8897 - 8907   2022.6

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    Repository Public URL： https://hdl.handle.net/2324/7181931

  • Band Engineering-Tuned Localized Surface Plasmon Resonance in Diverse-Phased Cu2–xSySe1–y Nanocrystals Invited Reviewed International journal

    Han Li, Masahiro Shibuta, Takashi Yamada, Hajime Hojo, Hiroyuki S Kato, Toshiharu Teranishi, Masanori Sakamoto

    The Journal of Physical Chemistry C   126 ( 18 )   8107 - 8112   2022.6

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    Repository Public URL： https://hdl.handle.net/2324/7179521

  • Rational Design of Cu-Doped ZnS Nanospheres for Photocatalytic Evolution of H<sub>2</sub> with Visible Light

    Liu, X; Zhang, Y; Matsushima, S; Sugiyama, T; Hojo, H; Einaga, H

    ACS APPLIED ENERGY MATERIALS   5 ( 2 )   1849 - 1857   2022.2   （ ISSN:2574-0962 ）

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    Publisher：ACS Applied Energy Materials  

    Photocatalytic reactions to produce hydrogen from water under visible-light irradiation are an important key process for solar energy utilization. Because Cu-doped ZnS undergoes redox reactions upon irradiation with visible light, these materials have been applied to hydrogen production. In this study, Cu-doped ZnS catalysts were prepared by a solvothermal method, and their structures were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and ultraviolet-visible spectroscopic studies. Cu-doped ZnS consists of nanospherical particles with a diameter of 50 nm. Cu<sup>2+</sup> doping in ZnS causes structural distortion of the ZnS. The local structures were analyzed by X-ray absorption fine structure studies. As the amount of Cu added to ZnS increased, the degree of distortion of the ZnS structure also increased, and this degree of distortion reached a maximum when the Cu/Zn ratio was 0.07 (7% Cu doping). Cu-doped ZnS exhibited high activity in the hydrogen production reaction from water using Na<inf>2</inf>S and Na<inf>2</inf>SO<inf>3</inf> as sacrificial agents under visible-light irradiation (λ > 420 nm), and the highest activity was observed at 7% Cu doping.

    DOI： 10.1021/acsaem.1c03323

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  • Enhanced catalytic performance of spinel-type Cu-Mn oxides for benzene oxidation under microwave irradiation

    Ding, SY; Zhu, C; Hojo, H; Einaga, H

    JOURNAL OF HAZARDOUS MATERIALS   424 ( Pt C )   127523   2022.2   （ ISSN:0304-3894 eISSN:1873-3336 ）

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    Language：English   Publisher：Journal of Hazardous Materials  

    Microwave-assisted heterogeneous catalytic oxidation of benzene was investigated over Cu-Mn spinel oxides. The spinel oxides were synthesized by a coprecipitation method from metal nitrate hydrolysis in a solution using tetramethylammonium hydroxide (TMAH) as a precipitation reagent. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption fine structure, scanning electron microscopy, transmission electron microscope and H<inf>2</inf>-temperature-programmed reduction studies. Microwave absorption by the Cu-Mn spinel oxide is mainly driven by dielectric losses (dielectric heating). Cu-Mn spinel oxide with a Cu/Mn ratio of 1 exhibited superior activity to single oxides under microwave heating, demonstrating lower apparent activation energy than that obtained under conventional heating. Microwave irradiation lowered the reaction temperature required for benzene oxidation compared with conventional heating. Transient tests were used to investigate the reactivity of oxygen species in the catalytic reaction, and the high reactivity of Cu-Mn spinel oxides was related to the high reactivity of lattice oxygen on the catalyst surface. The reactivity of the oxygen species was enhanced under microwave heating, leading to an enhanced benzene oxidation reaction. The combination of adsorption and catalytic oxidation processes using Cu-Mn spinel oxides and zeolites efficiently decomposed benzene at low concentrations.

    DOI： 10.1016/j.jhazmat.2021.127523

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  • Rational Design of Cu-Doped ZnS Nanospheres for Photocatalytic Evolution of H2with Visible Light Reviewed International journal

    Xin Liu, Ya Zhang, Shigenori Matsushima, Takeharu Sugiyama, Hajime Hojo, Hisahiro Einaga

    ACS Applied Energy Materials   5 ( 2 )   1849 - 1857   2022.2

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    Repository Public URL： https://hdl.handle.net/2324/7179520

  • Enhanced catalytic performance of spinel-type Cu-Mn oxides for benzene oxidation under microwave irradiation Invited Reviewed International journal

    Siyu Ding, Chen Zhu, Hajime Hojo, Hisahiro Einaga

    Journal of Hazardous Materials   424   127527   2022.2

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    Repository Public URL： https://hdl.handle.net/2324/7179519

  • Automatic electron hologram acquisition of catalyst nanoparticles using particle detection with image processing and machine learning Invited Reviewed International journal

    Fumiaki Ichihashi, Akira Koyama, Tetsuya Akashi, Shoko Miyauchi, Ken'ichi Morooka, Hajime Hojo, Hisahiro Einaga, Yoshio Takahashi, Toshiaki Tanigaki, Hiroyuki Shinada, Yasukazu Murakami

    Applied Physics Letters   120 ( 6 )   064103   2022.2

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    Repository Public URL： https://hdl.handle.net/2324/7161519

  • Atomic and Electronic Structure of Pt/TiO<sub>2</sub> Catalysts and Their Relationship to Catalytic Activity

    Hojo, H; Gondo, M; Yoshizaki, S; Einaga, H

    NANO LETTERS   22 ( 1 )   145 - 150   2022.1   （ ISSN:1530-6984 eISSN:1530-6992 ）

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    Understanding the nature of the interaction between a metal and support, which is known as the metal–support interaction, in supported metal catalysts is crucial to design catalysts with desired properties. Here, we have developed model Pt/TiO<inf>2</inf> catalysts based on the deposition of colloidal Pt nanoparticles and studied their atomic and electronic structures before and after a postdeposition treatment that induces catalytic activity using aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles calculations. Direct contact between Pt nanoparticles and TiO<inf>2</inf> is realized after the postdeposition treatment, which is accompanied by the formation of a Ti<sup>3+</sup> state on the TiO<inf>2</inf> surface close to the Pt nanoparticles and a Pt<sup>δ+</sup> state on the Pt nanoparticles. The origin of these two states and their effect on the catalytic properties are discussed. These findings pave the way for a comprehensive understanding of metal–support interactions in supported metal catalysts.

    DOI： 10.1021/acs.nanolett.1c03485

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  • Magnetic Ordering and Structural Transition in the Ordered Double-Perovskite Pb<sub>2</sub>NiMoO<sub>6</sub>

    Zhao, JF; Wang, X; Shen, X; Sahle, CJ; Dong, C; Hojo, H; Sakai, Y; Zhang, J; Li, WM; Duan, L; Chan, TS; Chen, CT; Falke, J; Liu, CE; Kuo, CY; Deng, Z; Wang, XC; Yu, RC; Yu, RZ; Hu, ZW; Greenblatt, M; Jin, CQ

    CHEMISTRY OF MATERIALS   34 ( 1 )   97 - 106   2022.1   （ ISSN:0897-4756 eISSN:1520-5002 ）

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    Publisher：Chemistry of Materials  

    The B-site-ordered double-perovskite Pb2NiMoO6 was prepared at high pressure and high temperature. The structural analysis of synchrotron powder X-ray diffraction data shows that Pb2NiMoO6 crystallizes into monoclinic symmetry with the space group Pc (no. 7), where the Ni and Mo ions are ordered in a rock-salt-type manner. The magnetic and specific heat characterizations reveal unusual two-step antiferromagnetic (AFM) transitions at 18 and 26 K for Pb2NiMoO6. The X-ray absorption spectra at the Ni-L2,3 edge and the Mo-L3 edge and the high-resolution partial fluorescence yield at the Pb-L3 edge indicate Pb2+2Ni2+Mo6+O6 valence states. Although in A2NiMoO6 (A = Sr2+, Pb2+, and Ba2+), the size of the A cation increases gradually from Sr2+ (1.44 Å) to Pb2+ (1.49 Å) to Ba2+ (1.61 Å), Pb2NiMoO6 exhibits much lower symmetry structure and AFM transition temperature, TN, compared with Sr2NiMoO6 (I4/m, TN = 81 K) and Ba2NiMoO6 (Fm3¯ m, TN = 64 K), which is attributed to the large distortion of NiO6 and MoO6 octahedra induced by the lone pair electron effect of Pb2+ with a 6s2 electronic configuration. Moreover, symmetry-breaking phase transition from a high-temperature centrosymmetric, cubic Fm3¯ m phase to a low-temperature non-centrosymmetric, monoclinic Pc phase was observed at 393-413 K in Pb2NiMoO6.

    DOI： 10.1021/acs.chemmater.1c02826

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  • One-step oxidation of benzene to phenol with H<sub>3</sub>PW<sub>12</sub>O<sub>40</sub> under photoirradiation: Effect of operating conditions

    Wang, ZR; Hojo, H; Einaga, H

    CHEMICAL ENGINEERING JOURNAL   427   2022.1   （ ISSN:1385-8947 eISSN:1873-3212 ）

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    Publisher：Chemical Engineering Journal  

    The synthesis of phenol by one-pot oxidation of benzene with dioxygen (O<inf>2</inf>) is a significant conceptual and practical challenge because benzene has low reactivity to O<inf>2</inf> at room temperature and ambient pressure. Furthermore, phenol is more reactive than benzene and is easily overoxidized, so complete oxidation is more likely to proceed in the benzene oxidation reaction, which generally results in lower phenol yield and selectivity. Herein, we report that a heteropolyacid H<inf>3</inf>PW<inf>12</inf>O<inf>40</inf> functions as a photocatalyst for benzene oxidation reaction in an aqueous acetonitrile solution using O<inf>2</inf> in high phenol yield (23–41%) and selectivity (80–90%). The addition of acetonitrile to the reaction solution significantly inhibited the complexation between phenol and H<inf>3</inf>PW<inf>12</inf>O<inf>40</inf>, preventing phenol overoxidation. Furthermore, no decomposition of H<inf>3</inf>PW<inf>12</inf>O<inf>40</inf> during the reaction was evidenced by UV–VIS spectra. This photocatalyst can be used repeatedly with only a slight decrease in the rate of phenol formation. For the mechanistic study, the initial rates, which depended on the reaction conditions, were investigated in detail. The benzene oxidation under anaerobic conditions was also conducted as a control experiment. A color change of reaction solution from colorless to blue has confirmed the reduction of H<inf>3</inf>PW<inf>12</inf>O<inf>40</inf> during the catalytic process and the formation of reduced H<inf>3</inf>PW<inf>12</inf>O<inf>40</inf> detected in the UV–VIS spectra. A kinetic isotope effect (KIE), k<inf>H</inf>/k<inf>D</inf> = 1.15, is found for the oxidation of benzene/benzene‑d<inf>6</inf>, indicating electron transfer is the principal C−H bond activation process in the mechanism. We identified hydrogen peroxide as an intermediate and found that phenol was generated in both the photocatalytic reduction and reoxidation process in our system.

    DOI： 10.1016/j.cej.2021.131369

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  • Fabrication and characterization of La-added MgFe2O4 as catalyst support for CO oxidation Invited Reviewed International journal

    Akane Doi, Kenji Obata, Shigenori Matsushima, Hajime Hojo, Hisahiro Einaga

    Ceramics International   47 ( 23 )   32793   2021.12

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    Repository Public URL： https://hdl.handle.net/2324/7181923

  • Magnetic Ordering and Structural Transition in the Ordered Double-Perovskite Pb2NiMoO6 Invited Reviewed International journal

    Jianfa Zhao, Xiao Wang, Xi Shen, Christoph J Sahle, Cheng Dong, Hajime Hojo, Yuki Sakai, Jun Zhang, Wenmin Li, Lei Duan, Ting-Shan Chan, Chien-Te Chen, Johannes Falke, Cheng-En Liu, Chang-Yang Kuo, Zheng Deng, Xiancheng Wang, Richeng Yu, Runze Yu, Zhiwei Hu, Martha Greenblatt, Changqing Jin

    Chemistry of Materials   34 ( 1 )   97 - 106   2021.12

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  • Analysis of TEM images of metallic nanoparticles using convolutional neural networks and transfer learning Invited Reviewed International journal

    Akira Koyama, Shoko Miyauchi, Ken'ichi Morooka, Hajime Hojo, Hisahiro Einaga, Yasukazu Murakami

    Journal of Magnetism and Magnetic Materials   538   168225   2021.11

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  • Topochemical synthesis of perovskite-type CuNb2O6 with colossal dielectric constant Invited Reviewed International journal

    Masayuki Fukuda, Ikuya Yamada, Hajime Hojo, Chihiro Takahashi, Yuya Yoshida, Katsuhisa Tanaka, Masaki Azuma, Koji Fujita

    JOURNAL OF MATERIALS CHEMISTRY C   9 ( 39 )   13981 - 13990   2021.10

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    DOI： 10.1039/d1tc01711j

  • Photocatalytic hydroxylation of benzene to phenol with dioxygen using sodium decatungstate Invited Reviewed International journal

    Ziru Wang, Hajime Hojo, Hisahiro Einaga

    Molecular Catalysis   515   11933   2021.10

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  • Controlling Diphenyl Ether Hydrogenolysis Selectivity by Tuning the Pt Support and H-Donors under Mild Conditions Reviewed International journal

    Chen Zhu, Siyu Ding, Hajime Hojo, Hisahiro Einaga

    ACS Catalysis   11 ( 20 )   12661 - 12672   2021.10

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  • Catalyst design of Pt/TiO2 microsphere for benzene oxidation under microwave irradiation Reviewed International journal

    Xin Liu, Siyu Ding, Saki Shigenobu, Hajime Hojo, Hisahiro Einaga

    Catalysis Today   376   285 - 291   2021.9

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  • Enhanced Piezoelectric Response in Orientation-Controlled BiFe1–xGaxO3 Thin Films with Polarization Rotation Reviewed International journal

    Keisuke Shimizu, Hajime Hojo, Masaki Azuma

    ACS Applied Electronic Materials   3 ( 10 )   4459 - 4464   2021.9

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  • Functional Transition Metal Perovskite Oxides with 6s2 Lone Pair Activity Stabilized by High-Pressure Synthesis Invited Reviewed International journal

    Masaki Azuma, Hajime Hojo, Kengo Oka, Hajime Yamamoto, Keisuke Shimizu, Kei Shigematsu, Yuki Sakai

    Annual Review of Materials Research   51   329 - 349   2021.6

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  • Observation of novel charge ordering and spin reorientation in perovskite oxide PbFeO3 Invited Reviewed International journal

    Ye, Xubin; Zhao, Jianfa; Das, Hena; Sheptyakov, Denis; Yang, Junye; Sakai, Yuki; Hojo, Hajime; Liu, Zhehong; Zhou, Long; Cao, Lipeng; Nishikubo, Takumi; Wakazaki, Shogo; Dong, Cheng; Wang, Xiao; Hu, Zhiwei; Lin, Hong-Ji; Chen, Chien-Te; Sahle, Christoph; Efiminko, Anna; Cao, Huibo; Calder, Stuart; Mibu, Ko; Kenzelmann, Michel; Tjeng, Liu Hao; Yu, Runze; Azuma, Masaki; Jin, Changqing; Long, Youwen

    NATURE COMMUNICATIONS   12 ( 1 )   2021.3

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    DOI： 10.1038/s41467-021-22064-9

  • Polarization Rotation at Morphotropic Phase Boundary in New Lead-Free Na1/2Bi1/2V1-xTixO3 Piezoceramics Invited Reviewed International journal

    Pan, Zhao; Zhang, Mao-Hua; Nishikubo, Takumi; Sakai, Yuki; Yamamoto, Hajime; Hojo, Hajime; Fukuda, Masayuki; Hu, Lei; Ishizaki, Hayato; Kaneko, Satoru; Kawaguchi, Shogo; Koruza, Jurij; Roedel, Juergen; Azuma, Masaki

    ACS APPLIED MATERIALS & INTERFACES   13 ( 4 )   5208 - 5215   2021.2

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    DOI： 10.1021/acsami.0c18482

  • Photocatalytic oxidation process for treatment of gas phase benzene using Ti3+ self-doped TiO2 microsphere with sea urchin-like structure Invited Reviewed International journal

    Liu, Xin; Zhang, Ya; Matsushima, Shigenori; Hojo, Hajime; Einaga, Hisahiro

    CHEMICAL ENGINEERING JOURNAL   402   2020.12

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    DOI： 10.1016/j.cej.2020.126220

  • Efficient visible light photocatalysis enabled by the interaction between dual cooperative defect sites Reviewed

    Rongjie Qi, Pengfei Yu, Jiachen Zhang, Weiqi Guo, Yaoyu He, Hajime Hojo, Hisahiro Einaga, Qun Zhang, Xiaosong Liu, Zhi Jiang, Wenfeng Shangguan

    Applied Catalysis B: Environmental   274   2020.10

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    Modifying photocatalyst with defects offers effective pathway to tailor light absorption properties, but may result in more sluggish kinetics. Therefore, enhanced light absorption often could not guarantee increased activity. Here, we report a dual defect strategy to extend light absorption with minimal loss in charge dynamics. Fine-tuned amount of dual defect, i.e., nitrogen defects and single-site copper, is simultaneously generated in polymer carbon nitride(PCN) through in-situ vapor diffusion method. Surface nitrogen defect extends the light absorption to long-wavelength via sub-band absorption. The interaction between nitrogen and single-site copper at certain concentration retains the charge dynamics by making the photogenerated electrons more delocalized through the newly-formed copper-nitrogen bonds. As a result, champion modified PCN exhibits robust hydrogen production activity, roughly 4.5-fold greater than the pristine counterpart in both visible and full light ranges. More intriguingly, this synergism provides PCN with efficient visible light activity even in faint tailing optical absorption region(>450 nm).

    DOI： 10.1016/j.apcatb.2020.119099

  • Perovskite-Type CuNbO3 Exhibiting Unusual Noncollinear Ferrielectric to Collinear Ferroelectric Dipole Order Transition Invited Reviewed International journal

    Fukuda, Masayuki; Yamada, Ikuya; Murata, Hidenobu; Hojo, Hajime; Hernandez, Olivier J.; Ritter, Clemens; Tanaka, Katsuhisa; Fujita, Koji

    CHEMISTRY OF MATERIALS   32 ( 12 )   5016 - 5027   2020.6

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    DOI： 10.1021/acs.chemmater.0c00444

  • Modulating the Structure and Magnetic Properties of ϵ-Fe2O3 Nanoparticles via Electrochemical Li+ Insertion Reviewed

    Sou Yasuhara, Yosuke Hamasaki, Tsukasa Katayama, Takahiro Ao, Yoshiyuki Inaguma, Hajime Hojo, Maarit Karppinen, Anish Philip, Shintaro Yasui, Mitsuru Itoh

    Inorganic chemistry   59 ( 7 )   4357 - 4365   2020.4

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    ϵ-Fe2O3, a metastable phase of iron oxide, is widely known as a roomerature multiferroic material or as a superhard magnet. Element substitution into ϵ-Fe2O3 has been reported in the literature; however, the substituted ions have a strong site preference depending on their ionic radii and valence. In this study, in order to characterize the crystal structure and magnetic properties of ϵ-Fe2O3 in the Fe2+/Fe3+ coexisting states, Li+ was electrochemically inserted into ϵ-Fe2O3 to reduce Fe3+. The discharge and charge of Li+ into/from ϵ-Fe2O3 revealed that Li+ insertion was successful. X-ray magnetic circular dichroism results indicated that the reduced Fe did not exhibit site preference. Increasing the Li+ content in ϵ-Fe2O3 resulted in decreased saturation magnetization and irregular variation of the coercive field. We present a comprehensive discussion of how magnetic properties are modified with increasing Li+ content using transmission electron microscopy images and considering the Li+ diffusion coefficient. The results suggest that inserting Li+ into crystalline ϵ-Fe2O3 is a useful tool for characterizing crystal structure, lithiation limit, and magnetic properties in the coexistence of Fe2+/Fe3+.

    DOI： 10.1021/acs.inorgchem.9b03302

  • Enhanced Negative Thermal Expansion Induced by Simultaneous Charge Transfer and Polar-Nonpolar Transitions Reviewed

    Takumi Nishikubo, Yuki Sakai, Kengo Oka, Tetsu Watanuki, Akihiko Machida, Masaichiro Mizumaki, Koki Maebayashi, Takashi Imai, Takahiro Ogata, Keisuke Yokoyama, Yoichi Okimoto, Shin Ya Koshihara, Hajime Hojo, Takashi Mizokawa, Masaki Azuma

    Journal of the American Chemical Society   2020.1

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    DOI： 10.1021/jacs.9b10336

  • Catalyst design of Pt/TiO2 microsphere for benzene oxidation under microwave irradiation Reviewed

    Xin Liu, Siyu Ding, Saki Shigenobu, Hajime Hojo, Hisahiro Einaga

    Catalysis Today   2020.1

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    Pt/TiO2 microspheres with sea-urchin like structures were prepared by sequential processes including the preparation of TiO2 by a hydrothermal method and the preheating of the TiO2, the deposition of Pt nanoparticles on the TiO2 surface, followed by post heating in O2/N2 and H2. The TiO2 and Pt/TiO2 catalysts were characterized by XRD, Raman, SEM, TEM and N2 adsorption studies. The average diameter of TiO2 microspheres was about 250 nm. The TiO2 microspheres were composed of TiO2 nanoparticles with the size of 20−30 nm. Pt particles with the size of 3 nm were highly dispersed on the TiO2 microsphere by liquid phase adsorption of colloidal Pt particles. The heating of TiO2 at 300 °C before and after the Pt deposition did not change the size of TiO2 microsphere and reduced the surface area from 238 to 137 m2 g-1. The Pt/TiO2 microsphere exhibited higher catalytic activity for benzene oxidation than Pt/TiO2 P25 under normal outer heating, whereas pristine TiO2 exhibited almost no activity. Activated carbon was used as a catalyst with a mixture of Pt/TiO2 microspheres when performing the catalytic reaction under microwave heating. The mixture of Pt/TiO2 and activated carbon showed higher benzene oxidation activity under microwave irradiation than under normal external heating. The mixture was applied to benzene adsorption-catalytic oxidation combined processes.

    DOI： 10.1016/j.cattod.2020.05.021

  • Catalytic Removal of Benzene at Mild Temperature over Manganese Oxide Catalysts Reviewed

    Hao Guo, Zhixiang Zhang, Hajime Hojo, Mingxia Chen, Hisahiro Einaga, Wenfeng Shangguan

    Catalysis Surveys from Asia   23 ( 3 )   199 - 209   2019.9

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    DOI： 10.1007/s10563-019-09268-2

  • Effect of catalyst composition and reactor configuration on benzene oxidation with a nonthermal plasma-catalyst combined reactor Reviewed

    Shoma Hamada, Hajime Hojo, Hisahiro Einaga

    Catalysis Today   144 - 152   2019.7

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    DOI： 10.1016/j.cattod.2018.07.055

  • Direct Observation of Magnetization Reversal by Electric Field at Room Temperature in Co-Substituted Bismuth Ferrite Thin Film Invited Reviewed International journal

    Keisuke Shimizu, Ryo Kawabe, Hajime Hojo, Haruki Shimizu, Hajime Yamamoto, Marin Katsumata, Kei Shigematsu, Ko Mibu, Yu Kumagai, Fumiyasu Oba, and Masaki Azuma

    Nano Letters   19 ( 3 )   1767 - 1773   2019.3

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    DOI： 10.1021/acs.nanolett.8b04765

  • Removal of benzene by non-thermal plasma catalysis over manganese oxides through a facile synthesis method Reviewed

    Hao Guo, Xin Liu, Hajime Hojo, Xin Yao, Hisahiro Einaga, Wenfeng Shangguan

    Environmental Science and Pollution Research   26 ( 8 )   8237 - 8247   2019.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1007/s11356-019-04264-5

  • Large Negative Thermal Expansion Induced by Synergistic Effects of Ferroelectrostriction and Spin Crossover in PbTiO3-Based Perovskites Invited Reviewed International journal

    Zhao Pan, Jun Chen, Runze Yu, Lokanath Patra, Ponniah Ravindran, Andrea Sanson, Ruggero Milazzo, Alberto Carnera, Lei Hu, Lu Wang, Hajime Yamamoto, Yang Ren, Qingzhen Huang, Yuki Sakai, Takumi Nishikubo, Takahiro Ogata, Zi'an Fan, Yawei Li, Guangqiang Li, Hajime Hojo, Masaki Azuma, and Zianran Xing

    Chemistry of Materials   31 ( 4 )   1296 - 1303   2019.2

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    Language：Japanese   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/acs.chemmater.8b04266

  • Sodium titanium oxide bronze nanoparticles synthesized via concurrent reduction and Na+-doping into TiO2(B) Invited Reviewed International journal

    George Hasegawa, Moeko Tanaka, Junie John M. Vequizo, Akira Yamakata, Hajime Hojo, Makoto Kobayashi, Masato Kakihana, Miki Inada, Hirofumi Akamatsu, and Katsuro Hayashi

    Nanoscale   11 ( 3 )   1442 - 1450   2019.1

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    Language：Japanese   Publishing type：Research paper (scientific journal)  

    DOI： 10.1039/c8nr08372j

  • Room temperature ferromagnetism in BiFe1-xMnxO3 thin film induced by spin-structure manipulation Reviewed

    Kei Shigematsu, Takeshi Asakura, Hajime Yamamoto, Keisuke Shimizu, Marin Katsumata, Haruki Shimizu, Yuki Sakai, Hajime Hojo, Ko Mibu, Masaki Azuma

    Applied Physics Letters   112 ( 19 )   2018.5

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.5024710

  • Systematic charge distribution changes in Bi- and Pb-3d transition metal perovskites Reviewed

    Masaki Azuma, Yuki Sakai, Takumi Nishikubo, Masaichiro Mizumaki, Tetsu Watanuki, Takashi Mizokawa, Kengo Oka, Hajime Hojo, Makoto Naka

    Dalton Transactions   47 ( 5 )   1371 - 1377   2018.1

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1039/c7dt03244g

  • Realization of Large Electric Polarization and Strong Magnetoelectric Coupling in BiMn3Cr4O12 Reviewed

    Long Zhou, Jianhong Dai, Yisheng Chai, Huimin Zhang, Shuai Dong, Huibo Cao, Stuart Calder, Yunyu Yin, Xiao Wang, Xudong Shen, Zhehong Liu, Takashi Saito, Yuichi Shimakawa, Hajime Hojo, Yuichi Ikuhara, Masaki Azuma, Zhiwei Hu, Young Sun, Changqing Jin, Youwen Long

    Advanced Materials   29 ( 44 )   2017.11

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1002/adma.201703435

  • High-Pressure Synthesis of the Cobalt Pyrochlore Oxide Pb2Co2O7 with Large Cation Mixed Occupancy Reviewed

    Junye Yang, Jianhong Dai, Zhehong Liu, Runze Yu, Hajime Hojo, Zhiwei Hu, Tunwen Pi, Yunliang Soo, Changqing Jin, Masaki Azuma, Youwen Long

    Inorganic Chemistry   56 ( 19 )   11676 - 11680   2017.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/acs.inorgchem.7b01646

  • A-Site and B-Site Charge Orderings in an s-d Level Controlled Perovskite Oxide PbCoO3 Reviewed

    Yuki Sakai, Junye Yang, Runze Yu, Hajime Hojo, Ikuya Yamada, Ping Miao, Sanghyun Lee, Shuki Torii, Takashi Kamiyama, Marjana Ležaić, Gustav Bihlmayer, Masaichiro Mizumaki, Jun Komiyama, Takashi Mizokawa, Hajime Yamamoto, Takumi Nishikubo, Yuichiro Hattori, Kengo Oka, Yunyu Yin, Jianhong Dai, Wenmin Li, Shigenori Ueda, Akihisa Aimi, Daisuke Mori, Yoshiyuki Inaguma, Zhiwei Hu, Takayuki Uozumi, Changqing Jin, Youwen Long, Masaki Azuma

    Journal of the American Chemical Society   139 ( 12 )   4574 - 4581   2017.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/jacs.7b01851

  • Temperature-Independent, Large Dielectric Constant Induced by Vacancy and Partial Anion Order in the Oxyfluoride Pyrochlore Pb2Ti2O6-δF2δ Reviewed

    Kengo Oka, Hajime Hojo, Masaki Azuma, Katsuyoshi Oh-Ishi

    Chemistry of Materials   28 ( 15 )   5554 - 5559   2016.8

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/acs.chemmater.6b02509

  • High-Temperature Monoclinic Cc Phase with Reduced c/a Ratio in Bi-based Perovskite Compound Bi2ZnTi1-xMnxO6 Reviewed

    Runze Yu, Narumi Matsuda, Ken Tominaga, Keisuke Shimizu, Hajime Hojo, Yuki Sakai, Hajime Yamamoto, Kengo Oka, Masaki Azuma

    Inorganic Chemistry   55 ( 12 )   6124 - 6129   2016.6

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/acs.inorgchem.6b00618

  • Atomic structures and oxygen dynamics of CeO2 grain boundaries Reviewed

    Bin Feng, Issei Sugiyama, Hajime Hojo, Hiromichi Ohta, Naoya Shibata, Yuichi Ikuhara

    Scientific Reports   6   2016.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1038/srep20288

  • Melting of Pb Charge Glass and Simultaneous Pb-Cr Charge Transfer in PbCrO3 as the Origin of Volume Collapse Reviewed

    Runze Yu, Hajime Hojo, Tetsu Watanuki, Masaichiro Mizumaki, Takashi Mizokawa, Kengo Oka, Hyunjeong Kim, Akihiko Machida, Kouji Sakaki, Yumiko Nakamura, Akane Agui, Daisuke Mori, Yoshiyuki Inaguma, Martin Schlipf, Konstantin Z. Rushchanskii, Marjana Ležaić, Masaaki Matsuda, Jie Ma, Stuart Calder, Masahiko Isobe, Yuichi Ikuhara, Masaki Azuma

    Journal of the American Chemical Society   137 ( 39 )   12719 - 12728   2015.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/jacs.5b08216

  • A new LiNbO3-type polar oxide with closed-shell cations ZnPbO3 Reviewed

    Runze Yu, Hajime Hojo, Teruyasu Mizoguchi, Masaki Azuma

    Journal of Applied Physics   118 ( 9 )   2015.8

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.4930034

  • Ferroelectricity and weak ferromagnetism of hexagonal ErFe O3 thin films Reviewed

    Hiroko Yokota, Tomoya Nozue, Shin Nakamura, Hajime Hojo, Mamoru Fukunaga, Pierre Eymeric Janolin, Jean Michel Kiat, Akio Fuwa

    Physical Review B - Condensed Matter and Materials Physics   92 ( 5 )   2015.8

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevB.92.054101

  • New PbTiO3-type giant tetragonal compound Bi2ZnVO6 and its stability under pressure Reviewed

    Runze Yu, Hajime Hojo, Kengo Oka, Tetsu Watanuki, Akihiko Machida, Keisuke Shimizu, Kiho Nakano, Masaki Azuma

    Chemistry of Materials   27 ( 6 )   2012 - 2017   2015.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1021/cm504133e

  • Suppression of temperature hysteresis in negative thermal expansion compound BiNi1-xFexO3 and zero-thermal expansion composite Reviewed

    K. Nabetani, Y. Muramatsu, K. Oka, K. Nakano, Hajime Hojo, M. Mizumaki, A. Agui, Y. Higo, N. Hayashi, M. Takano, M. Azuma

    Applied Physics Letters   106 ( 6 )   2015.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.4908258

  • Superconductivity in noncentrosymmetric iridium silicide Li2IrSi3 Reviewed

    Sunseng Pyon, Kazutaka Kudo, Jun Ichi Matsumura, Hiroyuki Ishii, Genta Matsuo, Minoru Nohara, Hajime Hojo, Kengo Oka, Masaki Azuma, V. Ovidiu Garlea, Katsuaki Kodama, Shin Ichi Shamoto

    Journal of the Physical Society of Japan   83 ( 9 )   2014.9

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.7566/JPSJ.83.093706

  • Magnetic structures of FeTiO3-Fe2O3 solid solution thin films studied by soft X-ray magnetic circular dichroism and ab initio multiplet calculations Reviewed

    Hajime Hojo, K. Fujita, H. Ikeno, T. Matoba, T. Mizoguchi, I. Tanaka, T. Nakamura, Y. Takeda, T. Okane, K. Tanaka

    Applied Physics Letters   104 ( 11 )   2014.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.4868638

  • Structural evolution and enhanced piezoresponse in cobalt-substituted BiFeO3thin films Reviewed

    Hajime Hojo, Ko Onuma, Yuichi Ikuhara, Masaki Azuma

    Applied Physics Express   7 ( 9 )   2014.1

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.7567/APEX.7.091501

  • Crystal structure and electrical properties of (1 -x)BiFeO 3-xBiCoO3 thin films prepared by pulsed laser deposition Reviewed

    Ko Onuma, Hajime Hojo, Yuichi Ikuhara, Masaki Azuma

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   61 ( 1 )   44 - 49   2014.1

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    Language：Japanese   Publishing type：Research paper (scientific journal)  

    DOI： 10.2497/jjspm.61.44

  • Effect of oxygen pressure on electrical properties of BiFe 0.9Co0.1O3 thin films prepared by pulsed laser deposition Reviewed

    Hajime Hojo, Ko Onuma, Yuichi Ikuhara, Masaki Azuma

    Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes   52 ( 9 PART2 )   2013.9

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.7567/JJAP.52.09KD09

  • Atomic structure of a σ3 [110]/(111) grain boundary in CeO 2 Reviewed

    B. Feng, Hajime Hojo, T. Mizoguchi, H. Ohta, S. D. Findlay, Yukio Sato, N. Shibata, T. Yamamoto, Y. Ikuhara

    Applied Physics Letters   100 ( 7 )   2012.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.3682310

  • Atomic structure and strain field of threading dislocations in CeO 2 thin films on yttria-stabilized ZrO2 Reviewed

    Hajime Hojo, Eita Tochigi, Teruyasu Mizoguchi, Hiromichi Ohta, Naoya Shibata, Bin Feng, Yuichi Ikuhara

    Applied Physics Letters   98 ( 15 )   2011.4

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.3575566

  • Magnetic properties of ilmenite-hematite solid-solution thin films Direct observation of antiphase boundaries and their correlation with magnetism Reviewed

    Hajime Hojo, Koji Fujita, Teruyasu Mizoguchi, Kazuyuki Hirao, Isao Tanaka, Katsuhisa Tanaka, Yuichi Ikuhara

    Physical Review B - Condensed Matter and Materials Physics   80 ( 7 )   2009.9

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevB.80.075414

  • Magnetic properties of disordered ferrite and ilmenite-hematite thin films Reviewed

    Katsuhisa Tanaka, Koji Fujita, Seisuke Nakashima, Hajime Hojo, Tomohiko Matoba

    Journal of Magnetism and Magnetic Materials   321 ( 7 )   818 - 821   2009.4

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.jmmm.2008.11.069

  • Fabrication of p-type ferrimagnetic semiconductor thin films based on FeTiO3-Fe2O3 solid solution Reviewed

    Hajime Hojo, Koji Fujita, Katsuhisa Tanaka, Kazuyuki Hirao

    Journal of Magnetism and Magnetic Materials   310 ( 2 SUPPL. PART 3 )   2105 - 2107   2007.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.jmmm.2006.10.782

  • Epitaxial growth of room-temperature ferrimagnetic semiconductor thin films based on the ilmenite-hematite solid solution Reviewed

    Hajime Hojo, Koji Fujita, Katsuhisa Tanaka, Kazuyuki Hirao

    Applied Physics Letters   89 ( 8 )   2006.9

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.2337276

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Presentations

  • Pt/CeO2触媒におけるPtとCeO2界面でのCe3+分布の結晶面依存

    北條 元、中島 美徳、吉﨑 達、永長 久寛

    セラミックス協会2025年年会  2025.3 

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    Event date： 2025.3

  • (La,Sr)CoO3-δ薄膜の作製とそのCO酸化特性

    井上尚祐哉、北條元、永長久寛

    第135回触媒討論会  2025.3 

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    Event date： 2025.3

  • Development of model catalysts and understanding their structure-property relationship Invited

    H. Hojo

    IOP-CAS Seminar  2025.2 

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    Event date： 2025.2

    Country：China  

  • Tuning the Piezoelectric and Multiferroic Properties of BiFeO3 Thin Films by Chemical Substitution Invited

    H. Hojo

    HPSTAR Seminar  2025.2 

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    Event date： 2025.2

    Venue：北京   Country：China  

  • Microstructures and CO oxidation properties of CeO2-δ ultrathin films

    Asuka Kai, Hajime Hojo, Hisahiro Einaga

    STAC14  2024.10 

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    Event date： 2024.10

  • Pt/TiO2(101)における酸素空孔分布とPtの電子状態

    鈴木隆玄、北條元、永長久寛

    日本顕微鏡学会学際的顕微研究領域　若手研究部会　2024年度シンポジウム  2024.10 

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    Event date： 2024.10

  • CeO2-d超薄膜の微構造とCO酸化特性

    甲斐飛翔、北條元、永長久寛

    日本顕微鏡学会学際的顕微研究領域　若手研究部会　2024年度シンポジウム  2024.10 

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    Event date： 2024.10

  • LaCoO3エピタキシャル薄膜のCO酸化特性と表面構造

    野澤悠輝、安達翔一、北條元、永長久寛

    第134回触媒討論会  2024.9 

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    Event date： 2024.9

  • Pt/TiO2薄膜モデル触媒における酸素空孔分布とPtの電子状態

    鈴木隆玄、北條元、永長久寛

    第85回応用物理学会秋季学術講演会  2024.9 

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    Event date： 2024.9

  • Pt/CeO2モデル触媒における担体上の酸素空孔量の定量的評価

    藤井和史、北條元、永長久寛

    第132回触媒討論会  2023.9 

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    Event date： 2024.4

    Language：Japanese  

    Country：Japan  

  • Atomic and Electronic Structure of Pt/TiO2 Model Catalysts and Their Relationship to Catalytic Activity International conference

    Hajime Hojo, Miki Gondo, Satoru Yoshizaki, Hisahiro Einaga

    IAMNano2023  2023.6 

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    Event date： 2024.4

    Language：Japanese  

    Country：Japan  

  • 酸化物触媒における格子酸素の反応性制御指針確立に関する研究 Invited

    北條元

    第61回オーロラセミナー  2023.8 

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    Event date： 2024.4

    Language：Japanese  

    Country：Japan  

  • Reduction Mechanism for CeO2 Revealed by Direct Observation of the Oxygen Vacancy Distribution in Shape-Controlled CeO2

    Hajime Hojo, Kazuki Hirota, So Ito, Hisahiro Einaga

    IMC20 Satellite Symposium  2023.9 

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    Event date： 2024.4

    Language：English  

    Country：Japan  

  • Pt/TiO2薄膜モデル触媒の作製とその原子・電子構造解析

    鈴木隆玄、北條元、永長久寛

    第132回触媒討論会  2023.9 

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    Event date： 2024.4

    Language：Japanese  

    Country：Japan  

  • SrCoO3-d薄膜の作製とそのCO酸化特性

    古賀幸、北條元、永長久寛

    第133回触媒討論会  2024.3 

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    Event date： 2024.4

    Language：Japanese  

    Country：Japan  

  • 結晶面・格子歪みと格子酸素の反応性の相関解明に関する研究 Invited

    北條元

    東京工業大学 第166回 フロンティア材料研究所学術講演会  2023.11 

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    Event date： 2024.4

    Language：Japanese  

    Country：Japan  

  • Ptを担持した形態制御CeO2ナノ粒子における酸素空孔分布の直接観察

    川本裕太、北條元、永長久寛

    第61回セラミックス基礎科学討論会  2023.1 

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    Event date： 2023.6

    Language：Japanese  

    Country：Japan  

  • The effect of SO2 on the catalytic properties of Pd/CeO2 International conference

    Saki Shigenobu, Hajime Hojo, Hisahiro Einaga

    TOCAT-9  2022.7 

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    Event date： 2023.6

    Language：English  

    Country：Japan  

  • Pt/CeO2モデル触媒における金属担体相互作用のナノ粒子サイズと結晶面依存性

    藤井和史、北條元、永長久寛

    第130回触媒討論会  2022.9 

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    Event date： 2023.6

    Language：Japanese  

    Country：Japan  

  • LaCoO3エピタキシャル薄膜の作製とそのCO酸化特性

    安達 翔一、北條 元、永長 久寛

    強的秩序とその操作に関わる 第16回 講演会  2023.1 

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    Event date： 2023.6

    Language：Japanese  

    Country：Japan  

  • 酸化セリウム薄膜へのエピタキシャル歪みの導入とその原子構造・電子状態解析

    日高州平、北條元、永長久寛

    第61回セラミックス基礎科学討論会  2023.1 

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    Event date： 2023.6

    Language：Japanese  

    Country：Japan  

  • Particle-size and crystal-plane-dependent metal-support interactions in Pt/CeO2 model catalysts International conference

    Kazushi Fujii, Hajime Hojo, Hisahiro Einaga

    The 19th Korea-Japan Symposium on Catalysis  2023.5 

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    Event date： 2023.5

    Language：English  

    Country：Korea, Republic of  

  • Fabrication of thin-film-based Pt/TiO2 model catalysts and their atomic and electronic structures International conference

    Ryugen Suzuki, Hajime Hojo, Hisahiro Einaga

    The 19th Korea-Japan Symposium on Catalysis  2023.5 

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    Event date： 2023.5

    Language：English  

    Country：Korea, Republic of  

  • Studies on reactivity of lattice oxygen in oxide catalysts Invited

    Hajime Hojo

    Functional Transition Metal Oxides by Design  2023.3 

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    Event date： 2023.3

    Language：English   Presentation type：Oral presentation (general)  

    Country：Japan  

  • Pd/BaCO3/Al2O3の触媒特性と硫黄被毒挙動に関する検討

    重信咲季、北條元、杉山武晴、永長久寛

    第130回触媒討論会  2022.9 

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    Event date： 2022.9 - 2023.6

    Language：Japanese  

    Country：Japan  

  • ペロブスカイト型酸化物触媒の耐硫黄被毒特性向上に関する検討

    北野史章、北條元、永長久寛

    第128回触媒討論会  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • Automatic Hologram Acquisition of Pt Catalyst Nanoparticles on TiO2 Using Particle Detection with Image Processing and AI Classification International conference

    Fumiaki Ichihashi, Akira Koyama, Tetsuya Akashi, Shoko Miyauchi, Ken'ichi Morooka, Hajime Hojo, Hisahiro Einaga, Toshiaki Tanigaki, Hiroyuki Shinada and Yasukazu Murakami

    Microscopy and Microanalyis 2021  2021.9 

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    Event date： 2022.6

    Language：English  

    Country：Japan  

  • Pd/CeO2への SO2吸着挙動に関する検討

    重信咲季，北條元，永長久寛

    第128回触媒討論会  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • 形態制御した酸化セリウムナノ粒子表面における酸素空孔量の定量化と異種元素の置換効果

    伊藤 蒼、廣田 利輝、北 條 元、永長 久寛

    日本セラミックス協会　第34回秋季シンポジウム  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • ペロブスカイト型Ni 酸化物の微構造と触媒特性

    園田 瑞歩、猪原 由香、北條 元、永長 久寛

    日本セラミックス協会　第34回秋季シンポジウム  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • Cu-Zn-Al 系酸化物の酸化還元特性制御

    永山 史也、北條 元、永長 久寛

    日本セラミックス協会　第34回秋季シンポジウム  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • 酸化マンガン担持ゼオライトの活性点構造とVOC分解特性の相関性

    Zheng Xuerui、北條元、永長久寛

    第128回触媒討論会  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • マイクロ波照射下におけるLa-Ni系ペロブスカイト型酸化物の昇温特性と触媒特性

    濱島達也、北條元、永長久寛

    第128回触媒討論会  2021.9 

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    Event date： 2022.6

    Language：Japanese  

    Country：Japan  

  • Mapping electrostatic potential around a Pt nanoparticle supported on TiO2 (110) International conference

    Yoshio Takahashi, Tetsuya Akashi, Hajime Hojo, Hisahiro Einaga, Hiroshi Nakajima, Toshiaki Tanigaki, Hiroyuki Shinada and Yasukazu Murakami

    Microscopy and Microanalyis 2021  2021.9 

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    Event date： 2021.8

    Language：English  

    Country：Japan  

▼display all

MISC

  • コバルト置換ビスマスフェライト薄膜における電場印加磁化反転 Reviewed

    重松圭、清水啓祐、北條元、東正樹

    日本物理学会誌   2023.12

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    Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

  • 次世代低消費電力メモリを実現するマルチフェロイック材料の開発 Invited Reviewed

    重松 圭、北條 元、東 正樹

    グリーンテクノロジー   1   47 - 51   2021

  • BiFe1-xCoxO3薄膜のスピン構造変化 ~電場による磁化の反転に成功、次世代低消費電力磁気メモリ実現の道開く~

    東 正樹、重松 圭、北條 元、壬生 攻

    NanoTechJapan Bulletin   13   1 - 5   2020

  • ペロブスカイトPbCrO3における電荷グラス状態

    北條元、Runze Yu、東正樹

    NEW GLASS、ニューガラスフォーラム   2016.11

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    Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

  • FeTiO3-Fe2O3固溶体薄膜における秩序構造および逆位相境界の直接観察

    北條 元、溝口 照康、幾原 雄一、藤田 晃司、田中 勝久、平尾 一之

    まてりあ   48 ( 12 )   598   2009

Industrial property rights

Patent   Number of applications: 1   Number of registrations: 1
Utility model   Number of applications: 0   Number of registrations: 0
Design   Number of applications: 0   Number of registrations: 0
Trademark   Number of applications: 0   Number of registrations: 0

Professional Memberships

  • 日本応用物理学会

  • 日本セラミックス協会

  • 触媒学会

Committee Memberships

  • 第38回日韓国際セラミックスセミナー現地実行委員  

    2024.10 - 2024.11   

  • 日本セラミック協会　第49回学術写真賞選考委員  

    2024.4 - 2025.3   

  • 日本セラミック協会　第48回学術写真賞選考委員  

    2023.4 - 2024.3   

  • 日本セラミック協会　第47回学術写真賞選考委員  

    2022.4 - 2023.3   

  • 日本セラミック協会　第46回学術写真賞選考委員  

    2021.4 - 2022.3   

  • 日本セラミック協会　第45回学術写真賞選考委員  

    2020.4 - 2021.3   

  • 強的秩序とその操作に関わる研究グループ　企画幹事  

    2015.4 - Present   

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Academic Activities

  • Screening of academic papers

    Role(s)： Peer review

    2024

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    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：10

  • Screening of academic papers

    Role(s)： Peer review

    2023

    　More details

    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：9

  • Screening of academic papers

    Role(s)： Peer review

    2022

    　More details

    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：14

  • Screening of academic papers

    Role(s)： Peer review

    2021

    　More details

    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：14

  • Screening of academic papers

    Role(s)： Peer review

    2020

    　More details

    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：10

  • Screening of academic papers

    Role(s)： Peer review

    2019

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    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：6

  • Screening of academic papers

    Role(s)： Peer review

    2018

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    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：9

  • Screening of academic papers

    Role(s)： Peer review

    2017

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    Type：Peer review 

    Number of peer-reviewed articles in foreign language journals：11

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Research Projects

  • 異相界面の定量化と触媒機能設計

    Grant number：23K26739  2023.4 - 2027.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    北條 元

    　 More details

    Grant type：Scientific research funding

    異なる結晶相が接する異相界面は、例えば半導体材料におけるダブルへテロ構造など新しい性質・機能の発現する舞台である。本研究では、申請者が独自に開発を進めているモデル触媒・モデル薄膜を対象として、原子分解能の透過電子顕微鏡法と第一原理計算を駆使し、異相界面について、原子構造・化学結合状態の観点からアプローチを行う。実用触媒を用いた解析では不可能であった異相界面を定量化することで、触媒設計の新しい方法論の構築を目指す。

    CiNii Research

  • 酸化物薄膜を用いたアプローチによる新しい触媒科学の発掘

    2023 - 2024

    三菱財団一般助成

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    Authorship：Principal investigator  Grant type：Contract research

  • 金属担持触媒の電気分極～高感度化された電子線ホログラフィーと雰囲気制御による解明

    Grant number：21H04623  2022 - 2024

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    村上 恭和, 松田 潤子, 吉岡 聰, 玉岡 武泰, 北條 元, 吉田 秀人

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    Authorship：Coinvestigator(s)  Grant type：Scientific research funding

    高感度化された電子線ホログラフィー（局所領域の電磁場解析技術）を駆使して、金属担持触媒材料における活性サイトと、その電荷分布・電位分布の特異性を明らかにする。この目的を達成するために、本研究ではガス雰囲気下での電子線ホログラフィー実験を敢行するとともに、画像取得時の電子照射量制御や、データ解析における情報科学的手法（ノイズと微弱信号の正確な分離技術等）を活用して、金属担持触媒が実働環境で示す状態の究明を試みる。

    CiNii Research

  • 金属・担体相互作用解明による金属担持触媒の高機能化

    2021 - 2024

    旭硝子財団ステップアップ助成

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    Authorship：Principal investigator  Grant type：Contract research

  • 革新的酸化物触媒実現のための格子酸素の反応性制御指針の確立

    2021 - 2023

    科学技術振興機構　創発的研究支援事業

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    Authorship：Principal investigator  Grant type：Contract research

  • Designing the reactivity of lattice oxygen by precisely controlling the lattice planes and strain

    Grant number：20H02824  2020 - 2022

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    Hojo Hajime

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    Authorship：Principal investigator  Grant type：Scientific research funding

    In this project, we have fabricated shape-controlled CeO2 nanoparticles and systematically studied the distribution of surface oxygen vacancies on {100} and {111} surfaces using scanning transmission electron microscopy and electron energy-loss spectroscopy, and the responses to H2 reduction treatments. It is successfully demonstrated that both catalytic activities and the ability to form oxygen vacancies are strongly dependent on the type of lattice planes. Moreover, the present results provide important insights into the reduction mechanism for CeO2, in which bulk oxygen instead of the widely believed surface capping oxygen makes no small contribution to the initial reduction step.

    CiNii Research

  • 室温マルチフェロイック薄膜における電場印加磁化反転機構の解明とデバイス動作実証

    Grant number：20K21092  2020 - 2021

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Challenging Research(Exploratory)

    北條 元

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    Authorship：Principal investigator  Grant type：Scientific research funding

    磁性と強誘電性が共存したマルチフェロイック物質において、電場による磁化の制御が可能であれば低消費電力の磁気メモリを実現できる。本研究では、室温で弱強磁性と強誘電性が共存したマルチフェロイックBiFe0.9Co0.1O3に着目し、まずはその電気分極反転機構を解明することで、電気分極反転に伴う磁化反転の可能性について検討する。続いて、実際に素子構造の作製し、電極を用いた電場印加による磁化反転の実証を試みる。

    CiNii Research

  • 複合機能を持つ新たな酸化物磁性体の物質探索とデバイス設計

    Grant number：17H01320  2017 - 2020

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

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    Authorship：Coinvestigator(s)  Grant type：Scientific research funding

  • 分極回転：巨大な圧電応答の設計と実現

    Grant number：17H04952  2017 - 2019

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (A)

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    Authorship：Principal investigator  Grant type：Scientific research funding

  • ビスマス・鉛ペロブスカイトのs-d軌道間電荷分布変化解明と巨大負熱膨張への展開

    Grant number：16H02393  2016 - 2018

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

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    Authorship：Coinvestigator(s)  Grant type：Scientific research funding

  • Bi系マルチフェロイック薄膜の磁気構造制御と電場による磁化反転の実現

    2016 - 2018

    旭硝子財団若手継続グラント

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    Authorship：Principal investigator  Grant type：Contract research

  • ナノ構造制御による巨大負熱膨張物質の開発

    Grant number：16H00883  2016 - 2017

    Japan Society for the Promotion of Science・Ministry of Education, Culture, Sports, Science and Technology  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

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    Authorship：Principal investigator  Grant type：Scientific research funding

  • 次世代メモリ実現のためのBi系マルチフェロイック材料の開発

    2015 - 2016

    新世代研究所研究助成

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    Authorship：Principal investigator  Grant type：Contract research

  • 電界誘起の構造相転移を用いた巨大な圧電応答の実現

    Grant number：26820291  2014 - 2015

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (B)

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    Authorship：Principal investigator  Grant type：Scientific research funding

  • 準安定酸化物薄膜の合成とスピン機能の創出

    Grant number：25249090  2013 - 2016

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

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    Authorship：Coinvestigator(s)  Grant type：Scientific research funding

  • ナノ構造の解析と制御によるBi系ペロブスカイト圧電体の開発

    2013 - 2014

    旭硝子財団研究助成

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    Authorship：Principal investigator  Grant type：Contract research

  • 基板の鋳型効果を用いた高圧相の安定化による非鉛圧電材料の開発

    2013

    日本板硝子材料工学助成会

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    Authorship：Principal investigator  Grant type：Contract research

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Educational Activities

  • 総合理工学府　総合理工学専攻　材料理工学メジャーにて「材料機能設計基盤特論I」や「先端表面反応化学」、「材料情報学特論III」を担当するとともに、工学部融合基礎工学科にて「結晶学基礎」、「セラミックス材料学I」等の講義を、基幹教育として「無機物質化学」や「基幹教育セミナー」等を担当することで、学部・大学院教育に従事している。

Class subject

  • セラミックス材料学Ⅰ

    2025.10 - 2025.12   Fall quarter

  • 先端表面反応化学 i

    2025.6 - 2025.8   Summer quarter

  • 基幹教育セミナー

    2025.6 - 2025.8   Summer quarter

  • 材料機能設計基盤特論 Ⅰ e

    2025.4 - 2025.6   Spring quarter

  • 結晶学基礎

    2025.4 - 2025.6   Spring quarter

  • セラミックス材料学Ⅰ

    2024.10 - 2024.12   Fall quarter

  • 物質材料科学実験Ⅲ

    2024.10 - 2024.12   Fall quarter

  • 材料情報学特論Ⅲ i

    2024.10 - 2024.12   Fall quarter

  • 物質材料科学実験Ⅱ

    2024.6 - 2024.8   Summer quarter

  • 先端表面反応化学 i

    2024.6 - 2024.8   Summer quarter

  • エネルギー物質工学実験Ⅱ（物質材料科学実験Ⅱ）

    2024.6 - 2024.8   Summer quarter

  • インターンシップⅡ（短期）

    2024.4 - 2025.3   Full year

  • 物質材料科学実験Ⅰ

    2024.4 - 2024.6   Spring quarter

  • エネルギー物質工学実験Ⅰ（物質材料科学実験Ⅰ）

    2024.4 - 2024.6   Spring quarter

  • 結晶学基礎

    2024.4 - 2024.6   Spring quarter

  • 材料機能設計基盤特論 Ⅰ e

    2024.4 - 2024.6   Spring quarter

  • セラミックス材料学I

    2023.10 - 2023.12   Fall quarter

  • 先端表面反応化学 i

    2023.6 - 2023.8   Summer quarter

  • 材料機能設計基盤特論 Ⅰ e

    2023.4 - 2023.6   Spring quarter

  • 結晶学基礎

    2023.4 - 2023.6   Spring quarter

  • 無機物質化学Ⅰ

    2023.4 - 2023.6   Spring quarter

  • 量子化学基礎

    2022.10 - 2022.12   Fall quarter

  • 材料情報学特論Ⅲ i

    2022.10 - 2022.12   Fall quarter

  • 先端表面反応化学 i

    2022.6 - 2022.8   Summer quarter

  • 材料機能設計基盤特論 Ⅰ e

    2022.4 - 2022.6   Spring quarter

  • 量子化学基礎

    2021.10 - 2021.12   Fall quarter

  • 先端表面反応化学 i

    2021.6 - 2021.8   Summer quarter

  • 無機物質化学Ⅱ

    2021.6 - 2021.8   Summer quarter

  • 材料機能設計基盤特論 Ⅰ e

    2021.4 - 2021.6   Spring quarter

  • 無機物質化学Ⅰ

    2021.4 - 2021.6   Spring quarter

  • 固体材料設計学

    2020.10 - 2021.3   Second semester

  • 課題集約演習

    2020.10 - 2021.3   Second semester

  • 量子化学基礎

    2020.10 - 2020.12   Fall quarter

  • 物質理工学修士実験第二

    2020.4 - 2021.3   Full year

  • 物質理工学修士演習第二

    2020.4 - 2021.3   Full year

  • 固体材料物性学

    2019.10 - 2020.3   Second semester

  • 固体材料設計学

    2019.10 - 2020.3   Second semester

  • 量子化学基礎

    2019.10 - 2019.12   Fall quarter

  • 物質理工学修士実験第二

    2019.4 - 2020.3   Full year

  • 物質理工学修士演習第二

    2019.4 - 2020.3   Full year

  • 量子化学基礎

    2018.10 - 2019.3   Second semester

  • 固体材料物性学

    2018.10 - 2019.3   Second semester

  • 物質理工学修士実験第二

    2018.4 - 2019.3   Full year

  • 物質理工学修士演習第二

    2018.4 - 2019.3   Full year

  • 無機物質化学

    2018.4 - 2018.9   First semester

  • 固体材料物性学

    2017.10 - 2018.3   Second semester

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Visiting, concurrent, or part-time lecturers at other universities, institutions, etc.

  • 2024  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2023  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2022  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2021  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2020  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2019  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2018  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

  • 2017  東京工業大学科学技術創成研究院フロンティア材料研究所  Classification:Part-time faculty  Domestic/International Classification:Japan 

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Other educational activity and Special note

  • 2024  Class Teacher  学部

  • 2023  Class Teacher  学部

  • 2022  Class Teacher  学部

  • 2022  Class Teacher  学部

  • 2021  Class Teacher  学部

  • 2020  Class Teacher  学部

  • 2019  Class Teacher  学部

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Media Coverage

  • 「未来の起源」に出演 TV or radio program

    TBS  2015.5

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    「未来の起源」に出演