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研究者情報

マスター

アカウント（マスター）

  • 氏名

    福島　知宏(フクシマ　トモヒロ), フクシマ　トモヒロ

所属（マスター）

  • 理学研究院　化学部門　物理化学分野

所属（マスター）

  • 理学研究院　化学部門　物理化学分野

独自項目

syllabus

  • 2021, 分子化学（先端物理化学）, Molecular Chemistry (Advanced Physical Chemistry), 修士課程, 総合化学院, 固体の電子状態、表面構造、表面分光、触媒
  • 2021, 化学実験Ⅳ, Laboratory Work in Chemistry IV, 学士課程, 理学部, 物理化学、電気化学、光と物質の相互作用、赤外分光法、蛍光分光法、真空、放電、電子衝撃分光法, エネルギー準位
  • 2021, 化学実験Ｃ, Laboratory Work in Chemistry C, 学士課程, 理学部, See the English version
  • 2021, 化学実験Ｄ, Laboratory Work in Chemistry D, 学士課程, 理学部, See the English version
  • 2021, 電気化学, Electrochemistry, 学士課程, 理学部, 電解質溶液、イオン、電池、電気化学ポテンシャル、表面構造、電子状態、バンド構造、エネルギー変換

researchmap

プロフィール情報

学位

  • 博士(工学)（京都大学）

プロフィール情報

  • 姓

    福島, フクシマ

  • 名

    知宏, トモヒロ

  • ID各種

    Q-3044-2017, 201801001853205286

対象リソース

業績リスト

研究分野

  • ナノテク・材料 / エネルギー化学
  • ナノテク・材料 / 基礎物理化学
  • ナノテク・材料 / 機能物性化学

経歴

  • 2023年10月 - 現在 JSTさきがけ「量子フロンティア」領域 研究者
  • 2022年06月 - 現在 北海道大学 大学院理学研究院 化学部門 講師
  • 2019年07月 - 現在 産業技術総合研究所 客員研究員
  • 2017年12月 - 2022年06月 北海道大学 大学院理学研究院 化学部門 助教
  • 2016年06月 - 2017年11月 名古屋大学 JST-ERATO 伊丹分子ナノカーボンプロジェクト 博士研究員
  • 2014年06月 - 2016年05月 日本学術振興会 海外特別研究員 (マサチューセッツ工科大学)
  • 2014年04月 - 2014年05月 京都大学iCeMS 博士研究員
  • 2011年04月 - 2014年03月 日本学術振興会 特別研究員 DC1

学歴

  • 2009年04月 - 2014年03月   京都大学大学院   工学研究科   合成・生物化学専攻
  • 2005年04月 - 2009年03月   京都大学   工学部   工業化学科

受賞

  • 2024年03月 電気化学会 光電気化学研究懇談会 第20回Honda-Fujishima Prize
  • 2022年09月 分子科学会 第15回分子科学会奨励賞
  • 2021年10月 日本分光学会 若手講演賞
  • 2014年06月 2014 Reaxys PhD Prize Finalist
  • 2013年03月 日本化学会 学生講演賞
  • 2012年06月 IACIS 2012 Soft Matter Poster Prize
  • 2010年09月 分子科学会 優秀ポスター賞
  • 2010年09月 錯体化学会 ポスター賞

論文

  • Tomohiro Fukushima, Kenko Tsuchimoto, Nobuaki Oyamada, Daiki Sato, Hiro Minamimoto, Kei Murakoshi
    The Journal of Physical Chemistry C 2024年11月14日 
    Oxygen evolution reaction (OER) is the counterpart in the hydrogen production by the water electrolysis. Further challenges have been required to bypass the energy consumption processes in OER. It is still important to unveil the OER intermediates toward the effective green hydrogen production. In this study, we conducted the in-situ Raman observation of the OER intermediates over Ni nanohole-array electrodes in the various electrolyte conditions. Ni nanohole-array electrodes were prepared with the interference exposure methods. Intense Raman peaks were observed from the Ni-OH, Ni-OOH, and active oxygen species as OER intermediates. The OER behavior can be classified with the reactants, such as OH− and H2O. The presented study demonstrates the importance of the electrolyte for the designing active OER catalysis for the next generation energy society.
  • Takahiro Hayashi, Tomohiro Fukushima, Kei Murakoshi
    The Journal of Chemical Physics 2024年11月14日
  • Daiki Sato, Nobuaki Oyamada, Tomohiro Fukushima, Kei Murakoshi
    Journal of Electroanalytical Chemistry 2024年11月
  • Andrei Stefancu, Javier Aizpurua, Ivano Alessandri, Ilko Bald, Jeremy Baumberg, Lucas V. Besteiro, Phillip Christopher, Miguel Correa-Duarte, Bart de Nijs, Angela Demetriadou, Renee Frontiera, Tomohiro Fukushima, Naomi Halas, Prashant K. Jain, Zee Hwan Kim, Dmitry Kurouski, Holger Lange, Jian-Feng Li, Luis Liz-Marzán, Ivan T. Lucas, Alfred J. Meixner, Kei Murakoshi, Peter Nordlander, William Peveler, Raul Quesada-Cabrera, Emilie Ringe, George C. Schatz, Sebastian Schlücker, Zachary D. Schultz, Emily Xi Tan, ZQ Tian, Lingzhi Wang, Bert Weckhuysen, Wei Xie, Xing Yi Ling, Jinlong Zhang, Zhao Zhi-Gang, Ru-Yu Zhou, Emiliano Cortes
    ACS Nano 2024年10月14日
  • Daiki Ashizawa, Masaki Itatani, Tomohiro Fukushima, Kei Murakoshi
    2024年07月02日
  • Nobuaki Oyamada, Hiro Minamimoto, Tomohiro Fukushima, Ruifeng Zhou, Kei Murakoshi
    Bulletin of the Chemical Society of Japan 97 2 2024年01月29日 
    Abstract This review introduces the preparation, observation, and characterization of systems of molecule polaritons. We summarize recent progress by our group on the control of molecular properties in the spaces of various optical cavities, such as plasmonic metal nanostructures and Fabry-Perot mirrors. After stating our motivations, we introduce topics on single-molecule observations based on surface-enhanced Raman scattering (SERS) spectroscopy. Our original findings are not limited to the ultra-sensitive detection of molecules/materials, but include unique resonant enhancements of SERS through exotic electronic excitation processes at electrified interfaces. Comprehensive analyses of SERS spectra provide novel routes to electronic excitation using plasmonic metal nanostructures. This behavior leads to the distinct photo-energy conversion based on excited electrons and holes with anomalous electrochemical potentials. Such unique resonant electronic excitation emerges a large optical force that can be used to manipulate small single molecules on surfaces in solution, even at room temperature. We also introduce systems for examining unique interactions between molecules and the optical modes of cavities, from single molecules to molecular ensembles. Plasmonic surface lattices and Fabry–Perot mirrors allow the formation of electronic and vibrational strong coupling states, respectively, showing unique properties of molecule polaritons, even under dark conditions, i.e., without photo-illumination.
  • Ben Wang, Tomohiro Fukushima, Hiro Minamimoto, Andrey Lyalin, Kei Murakoshi, Tetsuya Taketsugu
    2024年 
    A comprehensive understanding of the electrode-electrolyte interface in energy conversion systems remains challenging due to the complex and multifaceted nature of interfacial processes. This complexity hinders the development of more efficient electrocatalysts. In this work, we propose a hybrid approach to the theoretical description of the OER process on nickel-iron-based oxyhydroxides ($γ$-Ni$_{1-x}$Fe$_x$OOH) electrodes in alkaline media as a model system. Multiple reaction pathways represented by the single- and dual-site mechanisms were investigated by taking into account the realistic structure of the catalyst, the doping, and the solvation effects using a simple and computationally feasible strategy. Accounting for the variable solvation effects considerably affects the predicted overpotential in a roughly linear relationship between overpotential and dielectric constant. By incorporating quantum chemical simulations with kinetic modeling, we demonstrate that tuning the local solvation environment can significantly enhance the OER activity, opening new routine ways for elucidation of the emerging issues of OER processes on transition metal oxide surfaces and design of cost-effective, efficient electrocatalytic systems.
  • Tomoyuki Watanabe, Kenko Tsuchimoto, Tomohiro Fukushima, Kei Murakoshi, Minoru Mizuhata, Hiro Minamimoto
    Sustainable Energy & Fuels 2024年 
    The room-temperature liquid phase process was used to prepare α-Ni(OH)2 thin films with high crystallinity for use as oxygen evolution reaction catalysts under strong alkaline conditions. It was found that...
  • Tomohiro Fukushima, Motoki Fukasawa, Kei Murakoshi
    The Journal of Physical Chemistry Letters 14 30 6808 - 6813 2023年08月03日 
    The oxygen evolution reaction (OER) is a crucial electrochemical process for hydrogen production in water electrolysis. However, due to the involvement of multiple proton-coupled electron transfer steps, it is challenging to identify the specific elementary reaction that limits the rate of the OER. Here we employed a machine-learning-based approach to extract the reaction pathway exhaustively from experimental data. Genetic algorithms were applied to search for thermodynamic and kinetic parameters using the current-electrochemical potential relationship of the OER. Interestingly, analysis of the datasets revealed the energy state distributions of reaction intermediates, which likely originated in the interactions among intermediates or the distribution of multiple sites. Through our exhaustive analyses, we successfully uncovered the hidden energy profiles of the OER. This approach can reveal the reaction pathway to activate for efficient hydrogen production, which facilitates the design of catalysts.
  • Tomohiro Fukushima, Soushi Yoshimitsu, Kei Murakoshi
    Chemical Science 14 41 11441 - 11446 2023年06月23日 
    The energy states of molecules and the vacuum electromagnetic field can be hybridized to form a strong coupling state. In particular, it has been demonstrated that vibrational strong coupling can be used to modify the chemical dynamics of molecules. Here, we propose that ion dynamics can be altered through modifications of the dynamic hydration structure in a cavity vacuum field. We investigated the effect of different electrolyte species on ionic conductivity. Infrared spectroscopy of aqueous electrolyte solutions within the cavity confirmed the formation of vibrational ultrastrong coupling of water molecules, even in the presence of electrolytes. Interestingly, we observed significant enhancements in ionic conductivity, for specific alkali cations, particularly those classified as structure-breaking cations. These enhancements cannot be explained within the current theoretical framework for liquid electrolytes. Our analysis suggests that the vibrational strong coupling modifies the local dielectric friction experienced by hydrated ions. In addition, we propose the enthalpic and entropic modification of ionic conductivity through the systematic investigation of the hydration properties of different electrolytes. This study unveils the potential role of polaritons for exploring uncharted spaces in the design of materials with enhanced ionic conduction. Harnessing the unique properties of strong coupling and its influence on hydration dynamics could lead to the development of novel electrolytes and advancements in the field of ionic conduction.
  • Tomohiro Fukushima, Soushi Yoshimitsu, Kei Murakoshi
    Journal of the American Chemical Society 144 27 12177 - 12183 2022年07月13日 
    Hydrogen bonding interactions among water molecules play a critical role in chemical reactivity, dynamic proton mobility, static dielectric behavior, and the thermodynamic properties of water. In this study, we demonstrate the modification of ionic conductivity of water through hybridization with a vacuum electromagnetic field by strongly coupling the O─H stretching mode of H2O to a Fabry-Perot cavity mode. The hybridization generates collective vibro-polaritonic states, thereby enhancing the proton conductivity by an order of magnitude at resonance. In addition, the dielectric constants increase at resonance in the coupled state. The findings presented herein reveal how a vacuum electromagnetic environment can be engineered to control the ground-state properties of water.
  • Hiro Minamimoto, Ruifeng Zhou, Tomohiro Fukushima, Kei Murakoshi
    Accounts of Chemical Research 2022年03月15日 [査読有り]
  • Tomohiro Fukushima
    CURRENT OPINION IN ELECTROCHEMISTRY 35 2022年 
    As all the atoms in monolayer graphene are on its surface, it is strongly influenced by its environment. Surface-charge transfer of graphene changes its properties including the electrical conductivity, carrier mobility, capacitance, and reactivity. The charge transfer occurs between the graphene and its substrate, and can be controlled by the electrode potential in electrochemical cells. The charge of graphene is related to its Fermi level and Fermi energy, which determines the rates of the electrochemical and photoelectrochemical reactions occurring. The simplest method to measure the charge density of graphene is Raman spectroscopy. Here, we review Raman spectroscopy measurement of graphene charge, especially that in electrochemical environments, with emphasis on its potential application in electrochemical and photoelectrochemical reactions for energy conversion.
  • Fukushima, T., Ashizawa, D., Murakoshi, K.
    RSC Advances 12 21 2022年 [査読有り]
  • Tomohiro Fukushima, Soushi Yoshimitsu, Kei Murakoshi
    The Journal of Physical Chemistry C 125 46 25832 - 25840 2021年11月08日 [査読有り]
  • Tomohiro Fukushima, Soushi Yoshimitsu, Kei Murakoshi
    2021年06月21日
  • Tomohiro Fukushima, Hidetaka Hasebe, Kei Murakoshi
    Chemistry Letters 50 9 1604 - 1606 2021年06月19日 [査読有り]
     
    The proton permeation ability of graphene has been highlighted for use as proton exchange membranes in electrochemical devices. However, the tunability of proton permeation is still limited. We have developed molecular models for the theoretical study of the proton permeation ability of modified single-layer graphene structures. Energy calculations were employed for the evaluation of the barrier height and permeation rate. The proton permeation is tunable by the presence of covalently bonded molecules, which is useful for the design of tunable interfaces for proton permeation.
  • Fukushima, T., Miyauchi, A., Oyamada, N., Minamimoto, H., Motegi, T., Murakoshi, K.
    Journal of Nanophotonics 14 2 1 - 1 2020年 [査読有り][通常論文]
     
    Optical manipulation has been used for the trapping of micrometer-scaled objects, but it is still difficult to control the motion of small molecules on the nanometer scale at room temperature. Plasmonic metal nanostructures are expected to be useful for the optical manipulation of nanoscale molecules using a highly localized electric field. We use the plasmonic Ag nanostructure for a demonstration of optical trapping through the observation using surface-enhanced Raman scattering (SERS) imaging. The optical measurements were conducted under electrochemical potential control to stabilize the nanostructure with target molecules, 4,4′-bipyridyl (44 bpy). Upon increasing the concentration of 44 bpy molecules in an electrolyte solution at room temperature, the blinking frequency of the SERS signal was different in both the spectra and imaging. The dwell time of the SERS signals was increased from several tens of milliseconds to a few seconds, which suggested the successful observation of plasmonic trapping of small molecules through the surface diffusion control. The observed results prove the importance for the control of the surface coverage of the molecules and its influence on surface diffusion under plasmonic molecular trapping.
  • Tomohiro Fukushima, Akira Miyauchi, Nobuaki Oyamada, Shunpei Oikawa, Kei Murakoshi
    Proceedings of SPIE - The International Society for Optical Engineering 11141 2019年 [査読有り][通常論文]
     
    © Optics & Photonics International Congress 2019. Here, we describe Raman imaging of plasmonic Ag nanostructure for site-dependent molecular trapping analysis under electrochemical potential control. Ag nanostructure was prepared by nanosphere lithography (NSL) techniques with the polystyrene templates. Excitation of Ag nanostructure with 633 nm laser induced the fluorescence from Ag nanocluster and Raman signals from 4,4'-bipyridine molecules. Adsorption states of molecules were defined during optical measurements by controlling the electrochemical potential. Raman imaging was conducted depending on molecular concentration and light intensity to investigate the site-dependent molecular trapping analysis. We found that we can classify the spots showing anomaly in particular to the light intensity from Raman imaging.
  • Kaga, A., Fukushima, T., Shimokawa, J., Kitamura, M.
    Synthesis (Germany) 51 17 3214 - 3220 2019年 [査読有り][通常論文]
     
    Visible light photoredox conditions were applied to the traditional Fischer indole synthesis. N , N -Diarylhydrazones were efficiently converted into the corresponding indoles even at 30 degrees C by treatment with bromotrichloromethane in the presence of Ru(bpy) (3) Cl (2) center dot 6H (2) O as the photocatalyst. Electrochemical study revealed the viability of oxidative quenching cycle for the photocatalysis, which set the basis for proposing the redox-based reaction mechanism.
  • Kim, J., Fukushima, T., Zhou, R., Murakoshi, K.
    Materials 12 2 211 - 211 2019年 [査読有り][通常論文]
     
    Oxygen evolution reactions (OER) are important reactions for energy conversion. Metal-free carbon-based catalysts potentially contribute to the catalytic materials for OER. However, it has been difficult to understand the intrinsic catalytic activity of carbon materials, due to catalyst decomposition over the course of long-term reactions. Here, we report high oxygen evolution reaction catalytic activity of F-doped carbon in alkaline media. Intrinsic OER activity was evaluated from a combination of measurements using a rotating disk electrode and O-2 sensor. The F-doped carbon catalyst is a highly active catalyst, comparable to state-of-the-art precious-metal-based catalysts such as RuO2.
  • Murakoshi, Kei, Minamimoto, Hiro, Zhou, Ruifeng, Hasebe, Hidetaka, Yasuda, Kensuke, Fukushima, Tomohiro
    Journal of Physics: Conference Series 1220 1 2019年 [査読有り][通常論文]
     
    Electronic structure of monolayer graphene with metal contacts can be modified by control of interfacial interaction. Here, we show that the strength of local interfacial interaction between graphene and Au(111) surface can be electrochemically controlled by the hydrogen evolution reaction process. Graphene/Au(111) electrodes were prepared by the chemical vapour deposition. Raman spectroscopy indicated existence of monolayer of graphene over Au surface. Local interaction of graphene/Au(111) interaction can be differentiated by intercalation of H-2 molecules at interface. This study shed lights on the possibility of proton penetration through the graphene to modify the strength of interaction between graphene and Au(111) surface.
  • Fukushima, T., Murakoshi, K.
    Current Opinion in Electrochemistry 17 158 - 166 2019年 [査読有り][通常論文]
     
    Proton plays a critical role in electrochemical systems to control electrochemical reactivity or isotopic enrichment. Graphene is intensively investigated owing to its unique electronic structure and device fabrication. Through the structural tunability of graphitic materials by chemical or physical modification of the surface, graphene is revealed to be an ideal material for proton manipulation. Here, we review the use of graphene or graphitic materials toward the manipulation of proton with regard to the following three points. (1) Electronic properties of graphene: The electronic band structure of graphene can be modified by metal contacts owing to the interaction with a metal surface. (2) Molecular control of graphitic interface: The chemical structure of graphene can be modified, as is done in molecular chemistry, and can be used as a catalytic platform. (3) Proton conduction by graphene: Proton transport through a graphene layer occurs with a unique mechanism such as tunneling. We provide a perspective on the use of graphitic materials toward controlling the behavior of protons on the basis of the aforementioned points. From the above, graphene can be used as a platform for proton manipulation.
  • Sakakibara, Y., Ito, E., Fukushima, T., Murakami, K., Itami, K.
    Chemistry - A European Journal 24 37 9254 - 9258 2018年 [査読有り][通常論文]
     
    The rapid transformation of pharmaceuticals and agrochemicals enables access to unexplored chemical space and thus has accelerated the discovery of novel bioactive molecules. Because arylacetic acids are regarded as key structures in bioactive compounds, new transformations of these structures could contribute to drug/agrochemical discovery and chemical biology. This work reports carbon-nitrogen and carbon-oxygen bond formation through the photoredox-catalyzed decarboxylation of arylacetic acids. The reaction shows good functional group compatibility without pre-activation of the nitrogen- or oxygen-based coupling partners. Under similar reaction conditions, carbon-chlorine bond formation was also feasible. This efficient derivatization of arylacetic acids makes it possible to synthesize pharmaceutical analogues and bioconjugates of pharmaceuticals and natural products.
  • Fukushima, T., Sakamoto, H., Tanaka, K., Hijikata, Y., Irle, S., Itami, K.
    Chemistry Letters 46 6 855 - 857 2017年 [査読有り][通常論文]
     
    Molecular carbon nanorings, [n]cycloparaphenylenes ([n]CPP), are a unique class of porous molecules with allbenzene surface. Herein, we report the preparation of polymorphs of [6] CPP crystals for the first time, and the discovery of their packing structure-dependent properties. We found that the herringbone-packed structure is thermodynamically more stable than the tubular-packed structure. We revealed that their host-guest interaction depends on the packing structures of [6] CPP: the tubular-packing affords one-dimensional open channels for weak guest sorption, while the herringbone-packing gives closed cavities for strong guest entrapment. This study exemplifies that the solid-state host-guest chemistry of CPP crystals can be directed by controlling their packing structures.
  • Yoshidomi, T., Fukushima, T., Itami, K., Segawa, Y.
    Chemistry Letters 46 4 587 - 590 2017年 [査読有り][通常論文]
     
    A bimetallic acetate-bridged (bis-2-pyridylidene)Pd(II) complex was synthesized and its oxidation behavior was investigated by cyclic voltammetry. The density functional theory calculation indicated that bis-2-pyridylidene is a potentially useful ligand to stabilize bimetallic Pd(III) species owing to its strong electron donation ability and high planarity. The di-tert-butylphenyl-substituted (bis-2-pyridylidene) Pd(II) carbonate complex was synthesized via sequential C-H borylation and Suzuki-Miyaura cross-coupling reactions, and the carbonate complex was successfully converted into an acetate-bridged bimetallic complex. The structural parameters and oxidation potentials of the acetate-bridged (bis-2-pyridylidene) Pd(II) complex indicated the strong electron donation ability of the bis-2-pyridylidene ligand compared with neutral bidentate ligands. Despite several attempts, (bis-2-pyridylidene) Pd(III) complexes could not be isolated because of their instability.
  • Ito, E., Fukushima, T., Kawakami, T., Murakami, K., Itami, K.
    Chem 2 3 383 - 392 2017年 [査読有り][通常論文]
     
    In light of the importance of arylamine derivatives in organic materials, pharmaceuticals, and agrochemicals, the development of efficient aromatic C-H amination has long been sought after. Although many attempts have been made to achieve dehydrogenative C-H amination, the low reactivity of simple arenes renders equimolar coupling with amine derivatives a formidable task in synthetic chemistry. Herein, we report equimolar C-H/N-H coupling of arenes and sulfonimides through dehydrogenative aromatic imidation. Thiswas accomplished by means of a ruthenium-based photoredox mediator that employed the arene as the limiting reagent. A wide range of arenes, such as polycyclic aromatic hydrocarbons and heteroarenes, as well as a variety of sulfonimides, were applicable to the reaction. This electrochemistry-based mechanistic study has uncovered that the coupling reaction is initiated by the oxidation of sulfonimides by the ruthenium catalyst.
  • Chu, S.B., Fukushima, T., Surendranath, Y.
    Chemistry of Materials 29 2 495 - 498 2017年 [査読有り][通常論文]
     
    Researchers utilize classical amide formation reactions to install capping agents of varying chain lengths to surface carboxylic acid sites on Monarch 1300 carbon black. This surface treatment generates stable colloids that remain catalytically active for the aerobic oxidation of primary amines. Using the aerobic oxidation of benzylamine to N-benzyl-1-phenylmethanimine as a test reaction, they show that the capping ligand length negligibly impacts the rate of catalysis suggesting that, for linear aliphatic ligands, the ligand shell imposes minimal steric encumbrance on colloidal nanocatalysis.
  • Ricke, N.D., Murray, A.T., Shepherd, J.J., Welborn, M.G., Fukushima, T., Van Voorhis, T., Surendranath, Y.
    ACS Catalysis 7 11 7680 - 7687 2017年 [査読有り][通常論文]
     
    Using a combination of experimental and computational investigations, we assemble a consistent mechanistic model for the oxygen reduction reaction (ORR) at molecularly well-defined graphite-conjugated catalyst (GCC) active sites featuring aryl-pyridinium moieties (N+-GCC). ORR catalysis at glassy carbon surfaces modified with N+-GCC fragments displays near-first-order dependence in O-2 partial pressure and near-zero-order dependence on electrolyte pH. Tafel analysis suggests an equilibrium one-electron transfer process followed by a rate-limiting chemical step at modest overpotentials that transitions to a rate-limiting electron transfer sequence at higher overpotentials. Finite-cluster computational modeling of the N+-GCC active site reveals preferential O-2 adsorption at electrophilic carbons alpha to the pyridinium moiety. Together, the experimental and computational data indicate that ORR proceeds via a proton-decoupled O-2 activation sequence involving either concerted or stepwise electron transfer and adsorption of O-2, which is then followed by a series of electron/proton transfer steps to generate water and turn over the catalytic cycle. The proposed mechanistic model serves as a roadmap for the bottom-up synthesis of highly active N-doped carbon ORR catalysts.
  • Ogawa, T., Iyoki, K., Fukushima, T., Kajikawa, Y.
    Materials 10 12 2017年 [査読有り][通常論文]
     
    The field of porous materials is widely spreading nowadays, and researchers need to read tremendous numbers of papers to obtain a bird's eye view of a given research area. However, it is difficult for researchers to obtain an objective database based on statistical data without any relation to subjective knowledge related to individual research interests. Here, citation network analysis was applied for a comparative analysis of the research areas for zeolites and metal-organic frameworks as examples for porous materials. The statistical and objective data contributed to the analysis of: (1) the computational screening of research areas; (2) classification of research stages to a certain domain; (3) well-cited research areas; and (4) research area preferences of specific countries. Moreover, we proposed a methodology to assist researchers to gain potential research ideas by reviewing related research areas, which is based on the detection of unfocused ideas in one area but focused in the other area by a bibliometric approach.
  • Surendranath, Yogesh, O'Reilly, Matthew, Oh, Seokjoon, Jackson, Megan, Fukushima, Tomohiro, Chu, Sterling
    Abstracts of Papers of the American Chemical Society 251 2016年 [査読有り][通常論文]
  • Chu, Sterling, Marshall-Roth, Travis, Fukushima, Tomohiro, Kaminsky, Corey, Oh, Seokjoon, Jackson, Megan, Surendranath, Yogesh
    Abstracts of Papers of the American Chemical Society 252 2016年 [査読有り][通常論文]
  • Miner, E.M., Fukushima, T., Sheberla, D., Sun, L., Surendranath, Y., Dincə, M.
    Nature Communications 7 2016年 [査読有り][通常論文]
     
    Control over the architectural and electronic properties of heterogeneous catalysts poses a major obstacle in the targeted design of active and stable non-platinum group metal electrocatalysts for the oxygen reduction reaction. Here we introduce Ni-3(HITP)(2) (HITP = 2, 3, 6, 7, 10, 11-hexaiminotriphenylene) as an intrinsically conductive metal-organic framework which functions as a well-defined, tunable oxygen reduction electrocatalyst in alkaline solution. Ni-3(HITP)(2) exhibits oxygen reduction activity competitive with the most active non-platinum group metal electrocatalysts and stability during extended polarization. The square planar Ni-N-4 sites are structurally reminiscent of the highly active and widely studied non-platinum group metal electrocatalysts containing M-N-4 units. Ni-3(HITP)(2) and analogues thereof combine the high crystallinity of metal-organic frameworks, the physical durability and electrical conductivity of graphitic materials, and the diverse yet well-controlled synthetic accessibility of molecular species. Such properties may enable the targeted synthesis and systematic optimization of oxygen reduction electrocatalysts as components of fuel cells and electrolysers for renewable energy applications.
  • Surendranath, Yogesh, Fukushima, Tomohiro
    Abstracts of Papers of the American Chemical Society 250 2015年 [査読有り][通常論文]
  • Surendranath, Yogesh, Fukushima, Tomohiro, Kim, Rebecca
    Abstracts of Papers of the American Chemical Society 250 2015年 [査読有り][通常論文]
  • Fukushima, T., Drisdell, W., Yano, J., Surendranath, Y.
    Journal of the American Chemical Society 137 34 10926 - 10929 2015年 [査読有り][通常論文]
     
    Condensation of ortho-phenylenediamine derivatives with ortho-quinone moieties at edge planes of graphitic carbon generates graphite-conjugated pyrazines (GCPs) that are active for oxygen reduction electro-catalysis in alkaline aqueous electrolyte. Catalytic rates of oxygen reduction are positively correlated with the electrophilicity of the active site pyrazine unit and can be tuned by over 70-fold by appending electron-withdrawing substituents to the phenylenediamine precursors. Discrete molecular analogs containing pyrazine moieties display no activity above background under identical conditions. This simple bottom up method for constructing molecularly well-defined active sites on ubiquitous graphitic solids enables the rational design of tunable heterogeneous catalysts.
  • Inukai, M., Fukushima, T., Hijikata, Y., Ogiwara, N., Horike, S., Kitagawa, S.
    Journal of the American Chemical Society 137 38 12183 - 12186 2015年 [査読有り][通常論文]
     
    Rational design to control the dynamics of molecular rotors in crystalline solids is of interest because it offers advanced materials with precisely tuned functionality. Herein, we describe the control of the rotational frequency of rotors in flexible porous coordination polymers (PCPs) using a solid-solution approach. Solid-solutions of the flexible PCPs [{Zn(5-nitroisophthalate)(x)(5-methoxyisophthalate)(1-x)(deuterated 4,4'-bipyridyl)}(DMF-MeOH)](n) allow continuous modulation of cell volume by changing the solid-solution ratio x. Variation of the isostructures provides continuous changes in the local environment around the molecular rotors (pyridyl rings of the 4,4'-bipyridyl group), leading to the control of the rotational frequency without the need to vary the temperature.
  • Kongpatpanich, K., Horike, S., Sugimoto, M., Fukushima, T., Umeyama, D., Tsutsumi, Y., Kitagawa, S.
    Inorganic Chemistry 53 18 9870 - 9875 2014年 [査読有り][通常論文]
     
    We developed a new route for synthesis of Cr-based porous coordination polymers (PCPs) with azole ligands and characterized the unique open structures by single-crystal X-ray studies and other spectroscopy techniques. Chromium-based PCPs have been prepared from azolate ligands 3,5-dimethyl-1H-pyrazole-4-carboxylic acid (H2dmcpz) and 1,4-di(1H-tetrazole-5yl)benzene (H2BDT) by solvothermal reactions under an Ar atmosphere. [Cr3O(Hdmcpz)(6)(DMF)(3)]superset of DMF (1 superset of DMF) is a coordination compound that forms a hydrogen-bonded porous network. [Cr3O(HBDT)(2)(BDT)Cl-3)]?DMF (2 superset of DMF) possesses a new type of trinuclear chromium mu(3)-O unit cluster and the novel topology of a Cr-based PCP with 700 m(2) g(-1) of BrunauerEmmettTeller surface area. [Cr(BDT)(DEF)]superset of DEF (3 superset of DEF) is structurally flexible and reactive to O-2 molecules because of the unsaturated Cr2+ centers. This is the first report of a Cr-based PCP/metalorganic framework with noncarboxylate ligands and characterization by single-crystal X-ray diffraction.
  • Noro, S.-I., Hijikata, Y., Inukai, M., Fukushima, T., Horike, S., Higuchi, M., Kitagawa, S., Akutagawa, T., Nakamura, T.
    Inorganic Chemistry 52 1 280 - 285 2013年 [査読有り][通常論文]
     
    High selectivity and low-energy regeneration for adsorption of CO2 gas were achieved concurrently in a two-dimensional Cu(II) porous coordination polymer, [Cu-(PF6)(2)(4,4'-bpy)(2)] (4,4'-bpy = 4,4'-bipyridine), containing inorganic fluorinated PF6- anions that can act as moderate interaction sites for CO2 molecules.
  • Horike, S., Kamitsubo, Y., Inukai, M., Fukushima, T., Umeyama, D., Itakura, T., Kitagawa, S.
    Journal of the American Chemical Society 135 12 4612 - 4615 2013年 [査読有り][通常論文]
     
    A Ca2+ porous coordination polymer with ID channels was functionalized by the postsynthesis addition of LiCl to enhance the H+ conductivity. The compound showed over 10(-2) S cm(-1) at 25 degrees C and 20% relative humidity. Pulse-field gradient NMR elucidated that the fast H+ conductivity was achieved by the support of Li+ ion movements in the channel.
  • Hijikata, Y., Horike, S., Sugimoto, M., Inukai, M., Fukushima, T., Kitagawa, S.
    Inorganic Chemistry 52 7 3634 - 3642 2013年 [査読有り][通常論文]
     
    We have synthesized four porous coordination polymers (PCPs) using Zn2+, 4,4'-sulfonyldibenzoate (sdb), and four types of dinitrogen linker ligands, 1,4-diazabicyclo[2,2,2]octane (dabco), 1,4-bis(4-pyridyl)benzene (bpb), 3,6-bis(4-pyridy1)-1,2,4,5-tetrazine (bpt), and 4,4'-bipyridyl (bpy). The bent sdb ligands form a rhombic space connected by zinc paddle-wheel units to form a one-dimensional double chain, and each dinitrogen ligand linked the one-dimensional double chains. There are different assembled structures of two-dimensional sheets with the same connectivities between Zn2+ and the organic ligands. [Zn-2(sdb)(2)(dabco)](n) (1) has a noninterpenetrated and noninterdigitated structure, [Zn-2(sdb)(2)(bpb)](n) (2) and [Zn-2(sdb)(2)(bpt)](n) (3) have interdigitated structures, and [Zn-2(sdb)(2)(bpy)](n) (4) has an interpenetrated structure. The length of the dinitrogen ligands dominated their assembled structures and flexibility, which influence the adsorption properties. The flexible frameworks of 2 and 3 provide different stepwise adsorption behaviors for CO2, CH4, C2H6, and C2H4 affected by their pore diameters and the properties of the gases. Their different adsorption properties were revealed by IR spectroscopy and X-ray analysis under a gas atmosphere. The framework of 4 possesses less flexibility and a smaller void space than the others and a negligible amount of CH4 was adsorbed; however, 4 can adsorb either C2H6 or C2H4 through the gate-opening phenomenon. Measurement of the solid-state H-2 NMR was also carried out to investigate the relationship between the framework structure and the dynamics of bpy with regard to the lower flexibility of 4. We have demonstrated a strategy to control the pore size and assembled structures toward selective adsorption properties of PCPs.
  • Duan, J., Higuchi, M., Horike, S., Foo, M.L., Rao, K.P., Inubushi, Y., Fukushima, T., Kitagawa, S.
    Advanced Functional Materials 23 28 3525 - 3530 2013年 [査読有り][通常論文]
     
    A new porous coordination polymer, ([La(BTB)H2O]solvent (1guest)), is synthesized. Gas adsorption, ideal adsorbed solution theory (IAST) and breakthrough experiments of it exhibits high CH4 separation capability toward CO2 and C2 hydrocarbons at 273 K. In addition, this also shows good water and chemical stability, in particular, it is stable at pH = 14 at 100 degrees C, which is unprecedented for carboxylate-based porous coordination polymers. Furthermore, the effective adsorption site for separation is revealed by using an in situ diffuse reflectance IR fourier transform (DRIFT) spectra study.
  • Hirai, K., Chen, K., Fukushima, T., Horike, S., Kondo, M., Louvain, N., Kim, C., Sakata, Y., Meilikhov, M., Sakata, O., Kitagawa, S., Furukawa, S.
    Dalton Transactions 42 45 15868 - 15872 2013年 [査読有り][通常論文]
     
    Hybridized porous coordination polymers (PCPs) are synthesized through epitaxial growth or ligand replacement. Whereas epitaxial growth on the core crystal leads to a sandwich type PCP, ligand replacement near the surface of core crystal results in a core-shell type PCP.
  • Horike, S., Inubushi, Y., Hori, T., Fukushima, T., Kitagawa, S.
    Chemical Science 3 1 116 - 120 2012年 [査読有り][通常論文]
     
    Gas separation properties for CH4/CO2 and CH4/C2H6 of flexible 2D porous coordination polymers under equilibrium gas conditions and mixed gas flow conditions were investigated and the gas separation efficiencies were optimized by precise tuning of the flexibility in ligand-base solid solution compounds.
  • Yanai, N., Uemura, T., Inoue, M., Matsuda, R., Fukushima, T., Tsujimoto, M., Isoda, S., Kitagawa, S.
    Journal of the American Chemical Society 134 10 4501 - 4504 2012年 [査読有り][通常論文]
     
    We show that structural changes of a guest molecule can trigger structural transformations of a crystalline host framework. Azobenzene was introduced into a flexible porous coordination polymer (PCP), and cis/trans isomerizations of the guest azobenzene by light or heat successfully induced structural transformations of the host PCP in a reversible fashion. This guest-to-host structural transmission resulted in drastic changes in the gas adsorption property of the host guest composite, displaying a new strategy for creating stimuli-responsive porous materials.
  • Horike, S., Kishida, K., Watanabe, Y., Inubushi, Y., Umeyama, D., Sugimoto, M., Fukushima, T., Inukai, M., Kitagawa, S.
    Journal of the American Chemical Society 134 24 9852 - 9855 2012年 [査読有り][通常論文]
     
    We elucidated the specific adsorption property of CO2 for a densely interpenetrated coordination polymer which was a nonporous structure and observed gas separation properties of CO2 over CH4, C2H4, and C2H6, studied under both equilibrium and kinetic conditions of gases at ambient temperature and pressure.
  • Higuchi, M., Nakamura, K., Horike, S., Hijikata, Y., Yanai, N., Fukushima, T., Kim, J., Kato, K., Takata, M., Watanabe, D., Oshima, S., Kitagawa, S.
    Angewandte Chemie - International Edition 51 33 8369 - 8372 2012年 [査読有り][通常論文]
     
    Charged up: A novel porous coordination polymer with a charged organic surface (COS) comprising a zwitterionic organic linker, viologen, has been synthesized. The COS shows strong Lewis acidity accompanied with flexibility, and the isosteric heat of H2 adsorption is 9.5 kJ mol-1, which is comparable to that of open metal sites (OMSs). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Fukushima, T., Horike, S., Kobayashi, H., Tsujimoto, M., Isoda, S., Foo, M.L., Kubota, Y., Takata, M., Kitagawa, S.
    Journal of the American Chemical Society 134 32 13341 - 13347 2012年 [査読有り][通常論文]
     
    The mesoscale design of domain assembly is crucial for controlling the bulk properties of solids. Herein, we propose a modular design of domain assembly in porous coordination polymer crystals via exquisite control of the kinetics of the crystal formation process. Employing precursors of comparable chemical reactivity affords the preparation of homogeneous solid-solution type crystals. Employing precursors of distinct chemical reactivity affords the preparation of heterogeneous phase separated crystals. We have utilized this reactivity-directed crystallization process for the facile synthesis of mesoscale architecture which are either solid-solution or phase-separated type crystals. This approach can be also adapted to ternary phase-separated type crystals from one-pot reaction. Phase-separated type frameworks possess unique gas adsorption properties that are not observed in single-phasic compounds. The results shed light on the importance of crystal formation kinetics for control of mesoscale domains in order to create porous solids with unique cooperative functionality.
  • Quartapelle Procopio, E., Fukushima, T., Barea, E., Navarro, J.A.R., Horike, S., Kitagawa, S.
    Chemistry - A European Journal 18 41 13117 - 13125 2012年 [査読有り][通常論文]
     
    Herein, the synthesis, crystal structure, and full characterization of a new soft porous coordination polymer (PCP) of ([Cu2(dmcapz)2(OH2)]DMF1.5)n (1) formulation, which is easily obtained in the reaction of CuX2 (X=Cl, NO3) salts with 3,5-dimethyl-4-carboxypyrazole (H2dmcapz) is present. Compound 1 shows a copper(II) dinuclear secondary building unit (SBU), which is supported by two pyrazolate bridges and an unprecedented H2O bridge. The dinuclear SBUs are further bridged by the carboxylate ligands to build a diamondoid porous network. The structural transformations taking place in 1 framework upon guest removal/uptake has been studied in detail. Indeed, the removal of the bridging water molecules gives rise to a metastable evacuated phase (1?b) that transforms into an extremely stable porous material (1?c) after freezing at liquid-nitrogen temperature. The soaking of 1?c into water allows the complete and instantaneous recover of the water-exchanged material (1?a'). Remarkably, 1?b and 1?c materials possess structural bistability, which results in the switchable adsorptive functions. Therefore, the gas-adsorption properties of both materials have been studied by means of single-component gas adsorption isotherms as well as by variable-temperature pulse-gas chromatography. Both materials present permanent porosity and selective gas-adsorption properties towards a variety of gases and vapors of environmental and industrial interest. Moreover, the flexible nature of the coordination network and the presence of highly active convergent open metal sites confer on these materials intriguing gas-adsorption properties with guest-triggered framework-breathing phenomena being observed. The plasticity of CuII metal center and its ability to form stable complexes with different coordination numbers is at the origin of the structural transformations and the selective-adsorption properties of the studied materials.
  • Lin Foo, M., Horike, S., Fukushima, T., Hijikata, Y., Kubota, Y., Takata, M., Kitagawa, S.
    Dalton Transactions 41 45 13791 - 13794 2012年 [査読有り][通常論文]
     
    By adopting a ligand-based solid solution approach, the sulphonic acid functional group can be successfully incorporated into a porous coordination polymer with UiO-66 structure type. Zr6O4(OH)(4)(BDC-SO3H)(1.1)(BDC)(4.9) possesses enhanced heat of adsorption for carbon dioxide and acetone compared to Zr6O4(OH)(4)(BDC)(6).
  • Uemura, T., Kadowaki, Y., Kim, C.R., Fukushima, T., Hiramatsu, D., Kitagawa, S.
    Chemistry of Materials 23 7 1736 - 1741 2011年 [査読有り][通常論文]
     
    Sol gel polycondensation of tetramethoxysilane was performed in nanochannels of porous coordination polymers (PCPs), resulting in the formation of nanosized silica dispersed homogeneously inside the channels. In this system, the growth of silica was highly constrained, which increases the hydrophilic silanol moieties on the surface of silica particles. Deposition of silica particles into the nanochannels of PCPs could allow the remarkable alternations of the porous properties of the PCPs. Compared to the original PCP systems, adsorption of water was greatly enhanced because of the strong interaction between silica and water. The PCP silica nanocomposites preferred to adsorb 1,4-dioxane rather than cydohexane, showing the remarkable affinity of PCP silica hybrids to hydrophilic molecules. It is noteworthy that pore dimensionality of PCPs have properties of PCP silica hybrids. Compared to a PCP with three-dimensional interconnecting nanochannels, a PCP with one-dimensional porous system showed more significant gate effects on selectivity for the adsorbates. large effects on the adsorption
  • Fukushima, T., Horike, S., Inubushi, Y., Nakagawa, K., Kubota, Y., Takata, M., Kitagawa, S.
    Angewandte Chemie - International Edition 49 28 4820 - 4824 2010年 [査読有り][通常論文]
     
    (Figure Presented) My flexible friend: Separation of a CO2/ CH4 mixture was optimized by varying the composition of solid solutions of interdigitated 2D frameworks comprising two different isophthalate ligands (see picture). The characteristics of the solid solutions were dependent on the ligand ratio, which influenced the inherent flexibility and therefore the adsorption properties of the frameworks. © 2010 Wlley-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Inubushi, Y., Horike, S., Fukushima, T., Akiyama, G., Matsuda, R., Kitagawa, S.
    Chemical Communications 46 48 9229 - 9231 2010年 [査読有り][通常論文]
     
    The structural flexibility of Cu2+ interdigitated layer type framework was controlled and the compound represented clear separation property of CH4/CO2 at range of 0-1.0 MPa and recovery of adsorbed CO2 above 0.1 MPa.

MISC

担当経験のある科目（授業）

  • 電気化学北海道大学
  • 化学実験IV北海道大学
  • 自然科学実験北海道大学
  • 分子化学I(先端物理化学)北海道大学
  • 物質電子論北海道大学

所属学協会

  • 分子科学会   電気化学会   日本化学会   応用物理学会   日本分光学会   フラーレン・ナノチューブ・グラフェン学会   

共同研究・競争的資金等の研究課題

  • 科学技術振興機構：戦略的創造研究推進事業 さきがけ
    研究期間 : 2023年10月 -2026年03月 
    代表者 : 福島知宏
     
    本研究では共振場-物質の量子光学相互作用である強結合により、電気化学エネルギー変換の学理革新を目指します。真空場の局在性、電場強度の制御可能な共振場の創出を行います。水の物性制御を基軸とし、イオン伝導、電極触媒特性変調を分光電気化学的に評価を行い、結合強度の物性変化に与える寄与を明らかとします。また、熱と仕事の分配の強結合効果を検討することで、基礎学理の解明、エネルギー変換への応用を開拓します。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2022年06月 -2025年03月 
    代表者 : 村越 敬, 福島 知宏, 南本 大穂
     
    本研究においては水分子と共振場が強く相互作用したポラリトン状態に着目し、界面プロトン移動度制御に基づく多電子移動電極反応の効率化を目指す。共振器中において電解質水溶液のプロトン移動度が一桁上昇したことに端をなしており、共振器構造体を電極―電解質界面へと導入することによって、界面プロトン移動度制御を行い、触媒活性である過電圧低減や反応選択性を導入する試みである。 4電子移動反応である酸素発生反応を対象として、構造電極の与える効果に関して検討を行った。構造電極の作成はレーザーリソグラフィなどのトップダウンの手法を利用して行い、電気化学応答が十分に計測可能な面積での良好な矩形構造の作成に成功した。これらの構造体は赤外領域においてフォトニックバンドを有していることが明らかとなり、分子振動と共鳴可能な共振器構造体を電極―電解質界面において作成することに成功した。さらには触媒活性の構造依存性を検証するために電気化学電位制御下での顕微観察を導入し、活性の高い電極のスクリーニングが可能であることを実証した。構造電極の光学特性が水のOH伸縮振動と共鳴する場合には触媒活性が加速されることを明らかとした。さらには非緩衝溶液において観測されるOH－の拡散に由来する触媒電流の増大が確認され、従来の共振器において観測されていた界面のイオン移動度の制御が可能となることを実証した。またNi―Fe系触媒の開発も同時に行い、電極構造を保持したままでのFeドーピングによる活性向上も実証した。酸素発生反応の機構解析を網羅的に行うために熱力学―速度論パラメータの機械学習をもととした反応速度解析手法を開発した。これらの手法を利用することにより、実験データと同時に熱力学―速度論パラメータの網羅的探索および反応パスの検証を行うことを可能とした。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2022年04月 -2025年03月 
    代表者 : 村越 敬, 福島 知宏
     
    金属ナノ構造を可視光波長程度の間隔にて二次元配列整列した表面格子構造によって伝播型表面プラズモンSurface Lattice Resonance (SLR) モードを誘起する事が可能となる。SLR特性は600 nmから800 nmの間で精密に制御することが可能であり、プラズモン励起に伴う散乱特性が解説によって制御されることにより、長寿命な状態がSLR特性を有する金属ナノ構造配列電極に対して色素分子を結合させ、反応場の厚さを制御することにより、電気化学制御にもとづくRabi分裂エネルギーの精密制御に成功した。Rabi分裂エネルギーの変化からポラリトン形成に寄与する分子の空間分布を明らかにすることができ、SLRモードの真空場の電場空間分布が数100ナノメートルに達することを明らかとした。またSLRモードの先鋭化を利用することにより、結合強度が最大で0.5 程度の値を示す超強結合状態となる系の創出にも成功した。本系においては特徴的な多準位系のポラリトン状態が観測され、SLRに由来した長寿命なポラリトン状態が形成していると考えられる。またポラリトン状態におけるピークの半値幅としても0.1 eVを下回る先鋭なピークが観測され、励起状態における長寿命状態が示唆された。 電子移動反応へと拡張するために、単一電子移動反応および多電子移動反応での電子移動反応速度計測を確立した。これによりポラリトン状態における電子移動反応制御を確立する。
  • 分子修飾グラフェンによる燃料電池の創出
    公益財団法人 近藤記念財団：令和3年度（第8回）研究助成
    研究期間 : 2021年10月 -2023年09月 
    代表者 : 福島知宏
  • 振動強結合によるイオン伝導体の物性改革
    公益財団法人 豊田理化学研究所: 2022年度豊田理研スカラー：
    研究期間 : 2022年04月 -2023年03月 
    代表者 : 福島知宏
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2021年04月 -2023年03月 
    代表者 : 福島 知宏
     
    分子の有する振動エネルギーと真空場の光学エネルギーが量子相関を有することで振動ポラリトン状態という分子間にエネルギー相関を有する状態が創出される。特に結合エネルギーが大きいときには振動強結合状態と呼ばれる状態が生じ、近年では熱化学反応のダイナミクスを制御可能な指針として提案されている。振動強結合状態の電気化学系への適用とその原理探索を目的として、本年度は共振器中における水の振動強結合の観測と電解質水溶液のイオン伝導度変調に関して検討を行った。 分光計測および電気化学計測が適用可能なセルを開発し、電解質水溶液の厚さを数μm程度とした上で、角度依存分光計測を行ったところ、OH伸縮モードが共振器モードと強く結合することが明らかとなった。水の分子濃度に依存して結合強度を弱結合の領域から超強結合領域まで制御可能なことを明らかとした。さらには共振器の厚さを制御して、共振器モードを2,3,4次と制御したところ、超強結合状態下においては、共振器モードに依存して水の水素結合の状態がバルクとは異なることが示唆された(J. Phys. Chem. C, 2021)。 電気化学交流インピーダンス計測より、共振器中における電解質水溶液のイオン伝導度および誘電率に関して検討を行った。対照実験として、セル定数が同じでありながら、共振モードを有さないセルにおいてはイオン伝導度および誘電率はバルクの物性値と同じであった。一方で共振器中においては、誘電率の向上とイオン伝導度の向上が観測された。特にプロトン伝導度に関しては最大で1桁以上ものイオン伝導度の増大が明らかとなった。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2020年04月 -2022年03月 
    代表者 : 福島 知宏
     
    蓄電固体界面デバイスの発展に向けて、光の有する自由度を導入し、界面イオニクスの自由度の制御を目的として研究を行っている。特に局在表面プラズモン共鳴を利用した金属ナノ構造ー電解質界面におけるイオン伝導度の光制御および共振場におけるプロトン伝導の精密制御を行った。 従来の光照射におけるイオン伝導制御においては高エネルギー高強度の光照射が必要不可欠であった。局在表面プラズモン共鳴においては、光に対する高応答性が利用可能であり、光照射に伴い、局在光の電場形成に伴った、反応電子および正孔の生成と熱緩和過程が知られている。金属ナノ構造を配列させた構造上にNafion薄膜を作成した際には薄膜条件が数十ナノメートルの領域において、光照射に応じたイオン伝導度の低下が観測された。波長依存性に関してはLED光源を利用して検討したところ、消光計測で確認されたプラズモン共鳴に従って、イオン伝導度の低下が観測された。このことはイオン伝導度とプラズモン共鳴の間に相関があることを示唆している。 さらには光照射を必要としない真空場との相互作用を利用したイオン伝導変調も行った。分子の振動エネルギーと真空場の光学モードが一致する際にはポラリトン状態と呼ばれる物質ー真空場の混成状態が生じ、物性革新が生じることが知られている。実際に振動エネルギーと結合可能な共振器を作成し、振動強結合状態としたところ、イオン伝導度が増大することが確認された。 上記にあるように場の光学モードとイオン伝導体を相互作用させることにより、イオニクス物性が制御可能となることが示された。本研究で得られた成果をもとに、蓄電固体界面でのイオニクス物性の革新を目指す。
  • 金属ナノ構造による水分子集団特性の光機能化
    一般財団法人 イオン工学振興財団：2019年度研究助成
    研究期間 : 2019年09月 -2021年03月 
    代表者 : 福島 知宏
  • 金属ナノ構造を活用するプロトン伝導特性の多色光スイッチング
    公益財団法人 戸部眞紀財団：2019年度研究助成
    研究期間 : 2019年09月 -2020年08月 
    代表者 : 福島 知宏
  • 3次元分光イメージングに基づく固体電解質ー電極界面の機能解明
    公益財団法人 ノーステック財団：2019年度若手研究人材・ネットワーク育成補助金
    研究期間 : 2019年07月 -2020年03月 
    代表者 : 福島 知宏
  • 光電場で駆動する異方的固体イオニクス材料の創出
    北海道大学：令和元年度若手研究加速事業
    研究期間 : 2019年07月 -2020年03月 
    代表者 : 福島 知宏
  • 金属錯体ネットワークを基盤とする非平衡材料の創成
    日本学術振興会：海外特別研究員
    研究期間 : 2014年06月 -2016年05月 
    代表者 : 福島 知宏
  • 日本学術振興会：科学研究費助成事業 特別研究員奨励費
    研究期間 : 2011年04月 -2014年03月 
    代表者 : 福島 知宏
     
    同位体効果とは、その分子の一部の構成要素を同位体原子に置換した時にその諸物性に与える影響を指し、化学反応においては大きな効果を示すことが古くから知られている。一方で、電子物性や分子認識において同位体効果がほとんど生じないことが知られている。これは重元素によって誘起される、ゼロ点エネルギーの差が非常に小さいことに由来する。仮にこれらを達成することができれば、基礎的な知見だけではなく、同位体センサーや分離などの応用に向けた発展が期待できる。そこで、私は金属イオンと架橋配位子によって規則性構造を構築する多孔性金属錯体に着目し、研究を行った。 多孔性金属錯体によって誘起されるゲストのクラスター化現象を分子認識へと応用した。原子核の量子性により、分子間相互作用を通じてクラスター化の駆動力が異なるために、分子認識に応用できると考えた。実際にこのような考えのもと、同位体混合系からの実験を試みたところ、蒸留や電気分解などに代表される従来の手法よりも高い分子選択性が観測された。この成果に関しては現在論文投稿中である。 多孔性金属錯体によって形成される交互積層構造を利用し、電子状態の違いを誘起することにも成功した。ホスト骨格内部の表面上にパイ電子を露出している芳香環を利用し、ゲスト分子との間でのAAB型交互積層構造を形成した。ゲスト分子の幾何学的同位体効果を利用することで吸着構造に違いを誘起し、結果として紫外可視吸収スペクトルに大きな差を出すことに成功した。この電子状態の違いに関して固体NMRから検討を行ったところ、ホストゲストでの電子のやりとりの違いが、同位体効果によって誘起されるということが明らかとなった。この成果に関しては現在論文執筆中である。

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