Tsujikawa, Yuki

写真a

Affiliation

Faculty of Science and Technology, Department of Chemistry 表面化学研究室 ( Yagami )

Position

Assistant Professor (Non-tenured)/Research Associate (Non-tenured)/Instructor (Non-tenured)
Scopus Paper Info  
Paper Count: 27 Citation Count: 163 h-index: 7

Click to view the Scopus page. The data was downloaded from Scopus API in September 27, 2026, via http://api.elsevier.com and http://www.scopus.com .

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Career 【 Display / hide 】

  • 2021.04
    -
    2024.03

    日本学術振興会, 特別研究員(DC1)

  • 2024.04
    -
    2024.08

    東京大学物性研究所, 極限コヒーレント光研究所松田巌研究室, 特任助教

  • 2024.09
    -
    Present

    慶応義塾大学, 理工学部化学科, 助教（有期）

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Academic Background 【 Display / hide 】

  • 2015.04
    -
    2019.03

    Waseda University, 先進理工学部, 応用物理学科

    University, Graduated

  • 2019.04
    -
    2021.03

    Waseda University, 先進理工学研究科, 物理学及応用物理学専攻

    Graduate School, Completed, Master's course

  • 2021.04
    -
    2024.03

    The University of Tokyo, 理学系研究科, 物理学専攻

    Graduate School, Completed, Doctoral course

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Academic Degrees 【 Display / hide 】

  • 博士（理学）, The University of Tokyo, Coursework, 2024.03

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Papers 【 Display / hide 】

  • Existence of the Coadsorbed Phase of the CO Intermediates under CO2 Activation with Hydrogen on Ru(0001)

    Yu Murano, Masafumi Horio, Yifu Liu, Haruto Sakurai, Yuki Tsujikawa, Yoko Saito, Takeru Nakashima, Yasunobu Ando, Hiroshi Kondoh, Kenichi Ozawa, and Iwao Matsuda

    The Journal of Physical Chemistry C, 130 ( 29 ) 1026 - 10268 2026.07

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    The mechanism for CO2 activation on the Ru(0001) surface, the dominant surface of catalytic Ru nanoparticles, was elucidated using operando ambient-pressure X-ray photoelectron spectroscopy in CO2/H2. At 300 K, the major reaction was CO2 dissociation, generating CO adsorbates at both atop and bridge sites (COt* and COb*, respectively). The appearance of such a coadsorbed phase of COt* and COb* was reproduced by density functional theory calculations. At 370–470 K, these CO* species were converted to elemental carbon. Because the reaction condition matched the temperature ranges of the CO2 methanation on the Ru-based catalysts, COt* and COb* coadsorbed specifically at the interface between Ru(0001) and CO2/H2 gases seem to be the critical factor for elucidating the reaction mechanism.

  • Role of Quasi-One-Dimensional B Chains in the Catalytic Properties of CuB/Cu(111)

    Nakashima T., Tsujikawa Y., Kondo T., Koitaya T., Matsuda I., Ando Y.

    Journal of Physical Chemistry C 130 ( 15 ) 5411 - 5417 2026.04

    ISSN  19327447

    　View Summary

    The electron deficiency of boron leads to rich polymorphism and a high degree of freedom in material design. This research focuses on the newly reported CuB/Cu(111) surface and elucidates its catalytic properties. To assess its catalytic activity, this research investigates elementary steps relevant to CO<inf>2</inf> hydrogenation─specifically hydrogen, oxygen, and formate adsorption on this surface─by using a combination of first-principles calculations (OpenMX) and machine learning potentials (Matlantis). Our calculations verify five key points: (i) charge transfer occurs from copper atoms to boron chains, (ii) hydrogen atoms are observed to be adsorbed along the boron chain, (iii) hydrogen hopping between boron-tops shows three-center two-electron bonding in the transition state, (iv) surface oxidation can disrupt the boron chains, and (v) boron chains promote the adsorption of formate. In conclusion, the unique boron chains in CuB/Cu(111) can play a key role in the catalytic reactivity of this surface.

  • Adhesion between a borophane sheet and a metal substrate by interface bonding

    Yamaguchi K., Yin H., Niibe M., Tang J., Miyamoto M., Tsujikawa Y., Sakurai H., Murano Y., Ozawa K., Horio M., Yamaura J.i., Kondo T., Matsuda I.

    Applied Surface Science Advances 31 2026.01

    　View Summary

    Boron deposited on transition metal substrates has been actively investigated as a system that exhibits a wide range of surface structures. However, the specific case of nickel substrates remains largely unexplored. Nickel boride is used as a tribological material with excellent wear resistance and as a catalyst for hydrogenation, and its synthesis methods, structure, and functionality are being vigorously investigated. In this study, borophane, a two-dimensional material composed of hydrogen and boron, was heated to 300 °C in contact with a nickel substrate. We found that, compared with that annealed at 100 °C, annealed at 300 °C had a color that shifted toward longer wavelengths, and no longer dissolved in the synthesis solvent. However, x-ray diffraction and Fourier-transform infrared spectroscopy revealed no significant differences between the borophane samples annealed at 100 and 300 °C. X-ray absorption spectroscopy and x-ray photoelectron spectroscopy revealed that the surface oxide of nickel was reduced by borophane, resulting in the formation of nickel boride. Furthermore, thermal desorption spectroscopy showed that hydrogen desorbed from borophane upon contact with nickel, revealing that the borophane–nickel interface consisted of nickel boride and boron oxide layers. These findings provide insight into the surface science of boron on transition metal substrates and for the development of functional materials using these systems.

  • Discovery of bicyclic borane molecule B14H26

    Zhang X., Fujino T., Ando Y., Tsujikawa Y., Wang T., Nakashima T., Sakurai H., Yamaguchi K., Horio M., Mori H., Yoshinobu J., Kondo T., Matsuda I.

    Communications Chemistry 8 ( 1 )  2025.12

    　View Summary

    The discovery of fullerene following the synthesis of graphene marked a paradigm shift in chemistry. Here, we report the discovery of biycycloborane, arising from the synthesis of borophane (hydrogen boride). Uniquely, this synthesis method involves a decomposition mechanism rather than traditional atom-by-atom assembly, marking an unique approach to constructing complex borane structures. The mass spectrometry unveiled that the stable molecule has a mass of 178 in atomic mass unit with a stoichiometry of B<inf>14</inf>H<inf>26</inf>. Optical spectra and simulations further evidenced its bicyclic structure, featuring fulvene-like heptagons or octagons. This borane molecule, analogous to cyclic hydrocarbons, adopts a unit configuration with a three-center two-electron (3c-2e) bonding, akin to diborane. The B<inf>14</inf>H<inf>26</inf> molecule has been historically anticipated as a distant descendant of the dodecahedron borane, but it was born from the hydrogen boride sheet with a non-symmorphic symmetry. The discovery of biycycloborane expands the frontiers of boron chemistry, promising advancements in boron-based nanomaterials and beyond.

  • Electronic structure of the YCrB4 crystal surface, studied by micro-focused photoemission spectroscopy

    Zhang X., Tsujikawa Y., Miyamoto M., Yamaguchi K., Niibe M., Nishio-Hamane D., Yuan M., Ozawa K., Horio M., Yubuta K., Kondo T., Matsuda I.

    Physical Review Materials 9 ( 9 )  2025.09

    　View Summary

    We have performed a comprehensive electronic characterization of the needle-like single crystal YCrB4 metal boride, prepared by cleavage, characterized using angle-resolved photoemission spectroscopy with a microfocused beam. Our findings reveal the three-dimensional (3D) band structure of YCrB4, with band dispersions closely aligning with the first-principles calculations, confirming it is a topologically trivial insulator with a narrow band gap. Furthermore, a new metallic surface band was observed after cleavage, likely due to a space charge layer of the electron accumulation type. This study highlights the pivotal role of surface phenomena in shaping the electronic structure of YCrB4 and provides insights into the interplay between bulk and surface states, offering a path for exploring its potential applications in surface-sensitive technologies.

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Reviews, Commentaries, etc. 【 Display / hide 】

  • 表面金属放火物における周期及び準周期原子鎖構造の形成

    辻川夕貴, 松田巌

    日本放射光学会誌「放射光」 38 ( 2 ) 85 - 99 2025.03

    Article, review, commentary, editorial, etc. (scientific journal), Joint Work, Lead author

  • 全反射高速陽電子回折法による表面ホウ化銅の構造研究と新規ホウ素鎖の構造解明

    辻川夕貴，望月出海，和田健，兵頭俊夫，松田巌

    Photon Factory News 41 ( 2 ) 21 - 25 2023.08

    Article, review, commentary, editorial, etc. (bulletin of university, research institution), Lead author

  • Structure of the Boron Atomic Wire on Cu(111) and its Unique Relationships to the Carbon Chain Molecules

    Y. Tsujikawa and I. Matsuda

    Photon Factory Highlights 2022   8 - 9 2023.01

    Article, review, commentary, editorial, etc. (bulletin of university, research institution), Joint Work, Lead author

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Presentations 【 Display / hide 】

  • Recent Results of In Situ Surface Analysis Using APXPS at KEK, BL13 with a Focus on CO2 Reduction and Hydrogen Spillover

    Yuki Tsujikawa

    [International presentation]  Workshop on advanced X-ray photoemission spectroscopy, 

    2026.07
    , 

    Oral presentation (invited, special)

  • Structural Identification Using Positron Diffraction and Insights into Electronic Properties of Cu Boride Surfaces

    Yuki Tsujikawa

    The 76th REIMEI Workshop: Positron Diffraction Studies on 2D Materials and Related Novel Surface Analysis Techniques, 

    2026.03
    , 

    Oral presentation (invited, special)

  • Structure analysis of boron compound surfaces using positron beams

    Yuki Tsujikawa,　Takeru Nakashima,　Xiaoni Zhang,　Horio Masafumi, Izumi Mochizuki, Ken Wada, Toshio Hyodo, Fumio Komori, Takahiro Kondo, Yasunobu Ando, Hiroshi Kondoh, and Iwao Matsuda

    [International presentation]  The 10th International Symposium on Surface Sciecnce, 

    2025.12
    , 

    Oral presentation (general)

  • Formation and electronic structure of boron–metal composite atomic chains on a 2D surface　(会誌賞受賞記念講演)

    Yuki Tsujikawa, Xiaoni Zhang, Masafumi Horio, Fumio Komori, Takeru Nakashima, Yasunobu Ando, Takahiro Kondo and Iwao Matsuda

    [Domestic presentation]  Annual Meeting of the Japan Society of Vacuum and Surface Science 2025, 

    2025.10
    , 

    Oral presentation (invited, special)

  • Novel boron compounds and their unique structures

    Yuki Tsujikawa

    [Domestic presentation]  The Japan Society of Vacuum and Surface Science　The 8th Young Members Section Meeting &　Kanto Chapter 10th Anniversary Symposium, 

    2025.04
    , 

    Oral presentation (invited, special)

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

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Awards 【 Display / hide 】

  • 会誌賞

    (代表)Yuki Tsujikawa (他)Xiaoni Zhang, Masafumi Horio, Fumio Komori, Takeru Nakashima, Yasunobu Ando, Takahiro Kondo, Iwao Matsuda, 2025.10, 日本表面真空学会, Structure and Electronic State of Boron Atomic Chains on a Noble Metal (111) Surface

    Type of Award： Honored in official journal of a scientific society, scientific journal

  • 2023年度日本表面真空学会 女子大学院生優秀賞

    辻川夕貴, 2023.09, 日本表面真空学会, 銅基板上二次元ホウ化銅の探索と一次元ホウ素鎖の研究

    Type of Award： Award from Japanese society, conference, symposium, etc.

  • 学生奨励賞

    辻川夕貴, 2023.03, 量子ビームサイエンスフェスタ事務局

    Type of Award： Award from Japanese society, conference, symposium, etc.

  • 第11回 学生優秀発表賞受賞者 (領域9)

    辻川夕貴, 2022.09, 日本物理学会

    Type of Award： Award from Japanese society, conference, symposium, etc.

  • 第7回 学生優秀発表賞受賞者 (領域9）

    辻川夕貴, 2019.05, 日本物理学会

    Type of Award： Award from Japanese society, conference, symposium, etc.

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Courses Taught 【 Display / hide 】

  • LABORATORIES IN CHEMISTRY 1

    2026

  • LABORATORY IN SCIENCE

    2026

  • LABORATORY IN SCIENCE

    2025

  • LABORATORIES IN CHEMISTRY 1

    2025

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Memberships in Academic Societies 【 Display / hide 】

  • 日本物理学会, 

    2018
    -
    Present

  • 日本表面真空学会, 

    2018
    -
    Present
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