三輪 寛子

共通教育部(研究科)准教授
共通教育部(学域)准教授
基盤理工学専攻准教授
Ⅲ類(理工系)准教授
燃料電池・水素イノベーション研究センター准教授

学位

  • 博士(理学), 東京大学

研究キーワード

  • 触媒
  • 水素
  • TiO2
  • ミュオン
  • 酸素欠陥
  • 表面科学
  • 酸化物表面
  • AFM
  • 金ナノクラスター
  • PTRF-XAFS
  • TPRF-XAFS
  • 電気化学
  • 二酸化チタン
  • STM
  • ナノクラスター
  • 金クラスター

研究分野

  • ナノテク・材料, 機能物性化学

経歴

  • 2023年10月 - 現在
    電気通信大学, 大学院情報理工学研究科、情報理工学域共通教育部, 准教授
  • 2021年04月 - 2023年09月
    電気通信大学, 燃料電池・水素イノベーション研究センター, 特任准教授
  • 2016年 - 2021年03月
    北海道大学, 触媒科学研究所, 助教
  • 2010年 - 2015年
    北海道大学, 触媒化学研究センター, 助教

学歴

  • 2005年04月 - 2008年03月
    東京大学, 理学系研究科, 化学専攻博士課程, 日本国
  • 2003年04月 - 2005年03月
    東京大学, 理学系研究科, 化学専攻修士課程, 日本国
  • 2003年03月
    東京大学, 理学部, 化学科, 日本国

委員歴

  • 2024年04月 - 現在
    会誌編集委員, 日本表面真空学会
  • 2012年
    北海道支部役員, 日本化学会, 学協会, 日本化学会

受賞

  • 受賞日 2021年
    日本表面真空学会
    日本表面真空学会論文賞, 城戸大貴;上村洋平;三輪寛子;高草木達;朝倉清高
  • 受賞日 2015年
    日本化学会
    BCSJ(日本化学会欧文誌)賞, Tao Ma, Kotaro Miyazaki, Hiroko Ariga, Satoru Takakusagi, Kiyotaka Asakura
  • 受賞日 2005年
    Student Poster Award

論文

  • Subnanometric Osmium Clusters Confined on Palladium Metallenes for Enhanced Hydrogen Evolution and Oxygen Reduction Catalysis
    P Prabhu; Viet-Hung Do; Takefumi Yoshida; Yingtang Zhou; Hiroko Ariga-Miwa; Takuma Kaneko; Tomoya Uruga; Yasuhiro Iwasawa; Jong-Min Lee
    ACS Nano, American Chemical Society (ACS), 出版日 2024年03月29日
    研究論文(学術雑誌)
  • Pd Nanoparticles on the Outer Surface of Microporous Aluminosilicates for the Direct Alkylation of Benzenes using Alkanes
    Satoshi Misaki; Hiroko Ariga-Miwa; Takashi U. Ito; Takefumi Yoshida; Shingo Hasegawa; Yukina Nakamura; Shunta Tokutake; Moe Takabatake; Koichiro Shimomura; Wang-Jae Chun; Yuichi Manaka; Ken Motokura
    ACS Catalysis, American Chemical Society (ACS), 掲載ページ 12281-12287, 出版日 2023年09月06日
    研究論文(学術雑誌)
  • Dynamic Behavior of Intermediate Adsorbates to Control Activity and Product Selectivity in Heterogeneous Catalysis: Methanol Decomposition on Pt/TiO2(110)
    Can Liu; Bang Lu; Hiroko Ariga-Miwa; Shohei Ogura; Takahiro Ozawa; Katsuyuki Fukutani; Min Gao; Jun-ya Hasegawa; Ken-ichi Shimizu; Kiyotaka Asakura; Satoru Takakusagi
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 145巻, 36号, 掲載ページ 19953-19960, 出版日 2023年08月, Dynamic behavior of intermediate adsorbates, such as diffusion, spillover, and reverse spillover, has a strong influence on the catalytic performance in oxide-supported metal catalysts. However, it is challenging to elucidate how the intermediate adsorbates move on the catalyst surface and find active sites to give the corresponding products. In this study, the effect of the dynamic behavior of methoxy intermediate on methanol decomposition on a Pt/TiO2(110) surface has been clarified by combination of scanning tunneling microscopy (STM), temperature-programmed desorption (TPD), and density functional theory (DFT) calculations. The methoxy intermediates were formed by the dissociative adsorption of methanol molecules on Pt nanoparticles at room temperature followed by spillover to the TiO2(110) support surface. TPD results showed that the methoxy intermediates were thermally decomposed at >350 K on the Pt sites to produce CO (dehydrogenation) and CH4 (C-O bond scission). A decrease of the Pt nanoparticle density lowered the activity for the decomposition reaction and increased the selectivity toward CH4, which indicates that the reaction is controlled by diffusion and reverse spillover of the methoxy intermediates. Time-lapse STM imaging and DFT calculations revealed that the methoxy intermediates migrate on the five-fold coordinated Ti (Ti-5c) sites along the [001] or [1 (1) over bar 0] direction with the aid of hydrogen adatoms bonded to the bridging oxygens (O-br) and can move over the entire surface to seek and find active Pt sites. This work offers an in-depth understanding of the important role of intermediate adsorbate migration in the control of the catalytic performance in oxide-supported metal catalysts.
    研究論文(学術雑誌), 英語
  • Elucidation of Active Sites and Mechanistic Pathways of a Heteropolyacid/Cu-Metal-Organic Framework Catalyst for Selective Oxidation of 5-Hydroxymethylfurfural via Ex Situ X-ray Absorption Spectroscopy and In Situ Attenuated Total Reflection-Infrared Studies
    Paramita Koley; Subhash Chandra Shit; Takefumi Yoshida; Hiroko Ariga-Miwa; Tomoya Uruga; Tayebeh Hosseinnejad; Selvakannan Periasamy; Su-Il In; Dharmendra D. Mandaliya; Ravindra D. Gudi; Yasuhiro Iwasawa; Suresh K. Bhargava
    ACS CATALYSIS, AMER CHEMICAL SOC, 13巻, 9号, 掲載ページ 6076-6092, 出版日 2023年05月, Chemoselective oxidation of 5-hydroxymethylfurfural (HMF) over non noble metals to produce a bioplastic monomer, 2,5-furandicarboxylic acid (FDCA), under alkaline-free conditions is challenging and worthy of investigation. HMF oxidation into FDCA involves the concurrent oxidation of primary alcohol and an aldehyde functional group into carboxylic groups, which therefore demand a bifunctional catalyst containing dual active sites and chemoselective oxidation of HMF. The present work demonstrated the formation of new selective active sites in a composite porous material (CuBTC_PMA) that consists of Cu-BTC (metal-organic framework (MOF)) and polyoxometalate (POM). The porous framework provides (Cu-BTC_PMA) the desired chemoselectivity, while a selective Cu metal center in Cu-BTC (MOF) and Cu-O-Mo sites functions as active sites for the concurrent oxidation of HMF into FDCA. This catalyst exhibited a HMF conversion of 89% and an FDCA selectivity of 92.3% under base-free and mild reaction conditions. In detail, X-ray absorption spectroscopy analysis demonstrated the chemical bond tuning, as well as electronic structural modulations of MOF and POM at the molecular level, which directs the formation of new synergistic interfacial active sites and charge transfer states. This phenomenon causes the generation of the unique redox environment of copper and the multiple oxidation states along with the oxygen vacancy in the Cu-BTC_PMA catalyst, which most likely behaves as active sites for base-free oxidation. A kinetics study of this reaction was followed using in situ attenuated total reflection-infrared spectroscopy, demonstrating the stabilization of the specific intermediates that lead to the formation of FDCA. Moreover, we made comparative density functional theory and quantum theory of atoms in molecules investigations on the surface interaction between the reactant (HMF) and two catalyst models of Cu-BTC and Cu-BTC_PMA to interpret quantitatively the higher catalytic activity of the Cu-BTC_PMA catalyst. The kinetics study also evaluates the rate-determining step and activation energy for the multistep oxidation reactions.
    研究論文(学術雑誌), 英語
  • Stacking of a Cofacially Stacked Iron Phthalocyanine Dimer on Graphite Achieved High Catalytic CH4 Oxidation Activity Comparable to That of pMMO
    Yasuyuki Yamada; Kentaro Morita; Takuya Sugiura; Yuka Toyoda; Nozomi Mihara; Masanari Nagasaka; Hikaru Takaya; Kiyohisa Tanaka; Takanori Koitaya; Naoki Nakatani; Hiroko Ariga-Miwa; Satoru Takakusagi; Yutaka Hitomi; Toshiji Kudo; Yuta Tsuji; Kazunari Yoshizawa; Kentaro Tanaka
    JACS AU, AMER CHEMICAL SOC, 3巻, 3号, 掲載ページ 823-833, 出版日 2023年03月, Numerous biomimetic molecular catalysts inspired by methane monooxygenases (MMOs) that utilize iron or copper-oxo species as key intermediates have been developed. However, the catalytic methane oxidation activities of biomimetic molecule-based catalysts are still much lower than those of MMOs. Herein, we report that the close stacking of a mu- nitrido-bridged iron phthalocyanine dimer onto a graphite surface is effective in achieving high catalytic methane oxidation activity. The activity is almost 50 times higher than that of other potent molecule-based methane oxidation catalysts and comparable to those of certain MMOs, in an aqueous solution containing H2O2. It was demonstrated that the graphite-supported mu-nitrido-bridged iron phthalocyanine dimer oxidized methane, even at room temperature. Electrochemical investigation and density functional theory calculations suggested that the stacking of the catalyst onto graphite induced partial charge transfer from the reactive oxo species of the mu-nitrido-bridged iron phthalocyanine dimer and significantly lowered the singly occupied molecular orbital level, thereby facilitating electron transfer from methane to the catalyst in the proton-coupled electron-transfer process. The cofacially stacked structure is advantageous for stable adhesion of the catalyst molecule on the graphite surface in the oxidative reaction condition and for preventing decreases in the oxo-basicity and generation rate of the terminal iron-oxo species. We also demonstrated that the graphite-supported catalyst exhibited appreciably enhanced activity under photoirradiation owing to the photothermal effect.
    研究論文(学術雑誌), 英語
  • Pd‐PdO Nanodomains on Amorphous Ru Metallene Oxide for High‐Performance Multifunctional Electrocatalysis
    Viet‐Hung Do; P Prabhu; Vishal Jose; Takefumi Yoshida; Yingtang Zhou; Hiroko Miwa; Takuma Kaneko; Tomoya Uruga; Yasuhiro Iwasawa; Jong‐Min Lee
    Advanced Materials, Wiley, 掲載ページ 2208860-2208860, 出版日 2023年01月04日, 査読付, Developing highly efficient multifunctional electrocatalysts is crucial for future sustainable energy pursuits, but remains a great challenge. Herein, a facile synthetic strategy is used to confine atomically thin Pd-PdO nanodomains to amorphous Ru metallene oxide (RuO2). The as-synthesized electrocatalyst (Pd(2)RuOx-0.5 h) exhibits excellent catalytic activity toward the pH-universal hydrogen evolution reaction (eta(10) = 14 mV in 1 m KOH, eta(10) = 12 mV in 0.5 m H2SO4, and eta(10) = 22 mV in 1 m PBS), alkaline oxygen evolution reaction (eta(10) = 225 mV), and overall water splitting (E-10 = 1.49 V) with high mass activity and operational stability. Further reduction endows the material (Pd(2)RuOx-2 h) with a promising alkaline oxygen reduction activity, evidenced by high halfway potential, four-electron selectivity, and excellent poison tolerance. The enhanced catalytic activity is attributed to the rational integration of favorable nanostructures, including 1) the atomically thin nanosheet morphology, 2) the coexisting amorphous and defective crystalline phases, and 3) the multi-component heterostructural features. These structural factors effectively regulate the material's electronic configuration and the adsorption of intermediates at the active sites for favorable reaction energetics.
    研究論文(学術雑誌), 英語
  • Elimination of Indoor Volatile Organic Compounds on Au/SBA-15 Catalysts: Insights into the Nature, Size, and Dispersion of the Active Sites and Reaction Mechanism
    Emmanuel Iro; Hiroko Ariga-Miwa; Takehiko Sasaki; Kiyotaka Asakura; Maria Olea
    CATALYSTS, MDPI, 12巻, 11号, 出版日 2022年11月, Gold catalysts, with different particle sizes ranging from 19 to 556 angstrom, and supported on SBA-15 mesoporous silica, were prepared by using deposition-precipitation, co-precipitation, and impregnation methods. All samples were characterised by TEM, EXAFS, XPS, XRD, CFR (Continuous Flow Reactor), and TPR. The sample which proved to have the highest activity was characterised by TAP (Temporal Analysis of Products) as well. XPS, wide-angle XRD, EXAFS, and H-2-TPR measurements and data analysis confirmed that gold was present as Au-0 only on all samples. The size of the Au nanoparticle was determined from TEM measurements and confirmed through wide-angle XRD measurements. EXAFS measurements showed that as the Au-Au coordination number decreased the Au-Au bond length decreased. TEM data analysis revealed a dispersion range from 58% (for the smallest particle size) to 2% (for the highest particle size). For Au particles' sized lower that 60 angstrom, the Au dispersion was determined using a literature correlation between the dispersion and EXAFS Au-Au coordination number, and was in good agreement with the dispersion data obtained from TEM. The Au dispersion decreased as the particle size increased. CFR experiments validated the relationship between the size of the gold particles in a sample and the sample's catalytic activity towards acetone oxidation. The lowest temperature for the acetone 100% conversion, i.e., 250 degrees C, was observed over the reduced catalyst sample with the smallest particle size. This sample not only showed the highest catalytic activity towards acetone conversion, but, at the same time, showed high reaction stability, as catalyst lifetime tests, performed for 25 h in a CFR at 270 degrees C for the as-synthesised sample, and at 220 degrees C for the reduced sample, have confirmed. TAP (Temporal Analysis of Products) measurements and data analysis confirmed a weak competitive adsorption of acetone and oxygen over the Au/SBA-15 sample. Based on TAP data, a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms for acetone complete oxidation was proposed.
    研究論文(学術雑誌), 英語
  • Abnormal Metal Bond Distances in PtAu Alloy Nanoparticles: In Situ Back-Illumination XAFS Investigations of the Structure of PtAu Nanoparticles on a Flat HOPG Substrate Prepared by Arc Plasma Deposition
    Bing Hu; Bapurao Bharate; Juan D. Jimenez; Jochen Lauterbach; Naoto Todoroki; Toshimasa Wadayama; Kotaro Higashi; Tomoya Uruga; Yasuhiro Iwasawa; Hiroko Ariga-Miwa; Satoru Takakusagi; Kiyotaka Asakura
    JOURNAL OF PHYSICAL CHEMISTRY C, AMER CHEMICAL SOC, 126巻, 2号, 掲載ページ 1006-1016, 出版日 2022年01月, To reveal the origin of the difference between the Pt-Pt bond distance in Au(core)-Pt(shell)-type (PtAu) nanoparticles and that in a Pt overlayer on Au(111), alloy-type PtAu nanoparticles were prepared on a highly oriented pyrolytic graphite (HOPG) surface by arc plasma deposition and their structure was investigated under various electrochemical conditions by bent-crystal Laue analyzer (BCLA)-empowered back-illuminated X-ray absorption fine structure (BCLA + BI-XAFS) and high-energy-resolution fluorescence detection (HERFD)-empowered backi-lluminated X-ray absorption near-edge structure (HERFD + BIX-ANES) methods. On the basis of the XAFS analysis at both edges, we proposed the formation of a PtAu alloy core covered with a Pt-rich shell at 0.4 V-RHE, where the Pt-Pt, Pt-Au, and AuA-u bond lengths were all found to be similar to 2.76 angstrom. The Au-Au bond length was abnormally shorter than that for bulk Au. The Pt shell was dissolved under applied potentials greater than 0.8 V-RHE with the aid of the high-intensity X-rays, and the Au-Au distance increased. We concluded that the abnormal bond lengths were due to the strong surface tension from the Pt-rich shell and the relaxation of the lattice distortion. The Pt-Pt bond length in the PtAu nanoparticles decreases as a result of the surface tension of the nanoparticles; this surface tension does not exist on flat Au surfaces, where the lattice distortion between the Pt overlayer and the substrate is the main driving force for the expansion of the Pt-Pt bond length.
    研究論文(学術雑誌), 英語
  • Muonium response to low oxygen levels in haemoglobin and other biological aqueous solutions and potential application towards monitoring hypoxia
    Amba Datt Pant; Kanetada Nagamine; Eiko Torikai; Ichiro Shiraki; Koichiro Shimomura; Francis L. Pratt; Hiroko Ariga-Miwa; Katsuhiko Ishida; Jerome S. Schultz
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, ELSEVIER, 1011巻, 出版日 2021年09月, Low oxygen concentration or hypoxia plays a crucial role in the diagnosis and treatment of tumours and cancer. Although there are some existing techniques, such as proton magnetic resonance imaging (MRI), for the detection of molecular oxygen in tissues, new non-invasive techniques for directly measuring the extent and spatial distribution of hypoxia in cancerous or tumorous tissues are still needed. In this study, we propose a new non-invasive method using muons that are available in accelerator facilities, such as the Japan Proton Accelerator Research Complex in Japan and the Rutherford Appleton Laboratory in the UK. Unlike existing MRI methods, the proposed muon-based method can be applied without any external magnetic field. With the help of muonium response in solutions, we measured oxygen concentration in the aqueous solutions of various biological materials, such as haemoglobin, albumin, serum, and tris-buffered saline, under controlled molecular oxygen concentrations. The observed relaxation rate pattern of muonium through a fixed oxygen concentration sample and that with a sample concentration of less than 1% oxygen shows that this method may be applicable in detecting molecular oxygen levels in various tissues of the human body. Based on our experimental results, we have estimated the expected muonium spectra in normal physiological concentrations of haemoglobin in blood. Further systematic studies on other biological solutions are required before a potential clinical application of the method is devised.
    研究論文(学術雑誌), 英語
  • Close-Stacking of Iron-Oxo-Based Double-Decker Complex on Graphite Surface Achieved High Catalytic CH4 Oxidation Activity Comparable to that of Methane Monooxygenases
    Yasuyuki Yamada; Kentaro Morita; Takuya Sugiura; Yuka Toyoda; Nozomi Mihara; Masanari Nagasaka; Hikaru Takaya; Kiyohisa Tanaka; Takanori Koitaya; Naoki Nakatani; Hiroko Ariga-Miwa; Satoru Takakusagi; Yutaka Hitomi; Toshiji Kudo; Yuta Tsuji; Kazunari Yoshizawa; Kentaro Tanaka
    American Chemical Society (ACS), 出版日 2021年06月04日, <div><div><div><p>Herein, we report that the close-stacking of a double-decker-type dinuclear iron phthalocyanine complex on a graphite surface is effective for achieving high methane oxidation activity, comparable to those of certain MMOs, in an aqueous solution. </p></div></div></div>
  • Thorough Search Analysis of Extended X-ray Absorption Fine Structure Data for Complex Molecules and Nanomaterials Applications (vol 18, pg 249, 2020)
    Daiki Kido; Yohei Uemura; Yuki Wakisaka; Hiroko Ariga-Miwa; Satoru Takakusagi; Kiyotaka Asakura
    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY, SURFACE SCI SOC JAPAN, 18巻, 掲載ページ 268-268, 出版日 2020年09月
    英語
  • Thorough Search Analysis of Extended X-ray Absorption Fine Structure Data for Complex Molecules and Nanomaterials Applications
    Daiki Kido; Yohei Uemura; Hiroko Ariga-Miwa; Satoru Takakuasgi; Kiyotaka Asakura
    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY, SURFACE SCI SOC JAPAN, 18巻, 掲載ページ 249-261, 出版日 2020年08月, Extended X-ray absorption fine structure (EXAFS) plays an important role in the surface science and nanotechnology to characterize the non-crystalline materials using the curve fitting (CF) analysis. However, the CF has problems such as correlation between the structural parameters, the dependence on initial parameters, and the limitation of degree of freedom when EXAFS is applied to the complex system. In this paper, we propose a thorough search (TS) method to solve these problems. We analyzed EXAFS data for molybdenum oxide (alpha-MoO3) using the TS method. MO3 possesses a well-defined but complex local structure in which a central molybdenum (Mo) atom is surrounded by six oxygen (0) atoms. In CF analysis, the correlations of these six Mo-O bonds make it very difficult to derive reliable structural parameters from EXAFS data. In the TS analysis, the structural parameters regarded as a point (P) were surveyed thoroughly over a certain range. The goodness of fit was evaluated by R-factor. All P with R-factors less than a certain value were accepted. The accepted points P made a domain in which it was assumed that all points P in the domain should occur with equal probability and consequently their averages were used as representative structural parameters. If multiple independent domains were obtained, they were all regarded as possible candidates and the TS analysis provided possible structural parameters. The feasibility and advantages of the TS method were compared with the CF analysis and the micro reverse Monte Carlo method.
    研究論文(学術雑誌), 英語
  • A new interpretation of the root 7x root 7 R19.1 degrees structure for P adsorbed on a Ni(111) surface
    Barrow Elizabeth; Seuser Grant S; Ariga-Miwa Hiroko; Chen Donna A; Lauterbach Jochen; Asakura Kiyotaka
    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, TAYLOR & FRANCIS LTD, 20巻, 1号, 掲載ページ 379-387, 出版日 2019年12月31日, 査読付, We have studied P adsorption on Ni(111), a system which shows complex adsorbate structures. We determined the phase diagram of the surface P adsorbed on Ni(111). At low coverage, amorphous P was observed. At temperatures between 373 and 673 K and coverages above 0.1 monolayer, we found a structure, but above 673 K, other complex structures were created. These structures seemed to correlate with each other and we reinterpret a structure of P adsorbed on Ni(111) based on the similarities of these surface structures. The new rectangular structure for the is discussed in relation to the Ni2P local structure.[GRAPHICS].
    英語
  • Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts Electronic supplementary information (ESI) available. See DOI: 10.1039/c9cy01404g
    Takashi Toyao; Kah Wei Ting; S. M. A. Hakim Siddiki; Abeda S. Touchy; Wataru Onodera; Zen Maeno; Hiroko Ariga-Miwa; Yasuharu Kanda; Kiyotaka Asakura; Ken-ichi Shimizu
    CATALYSIS SCIENCE & TECHNOLOGY, ROYAL SOC CHEMISTRY, 9巻, 19号, 掲載ページ 5413-5424, 出版日 2019年10月, The structure and performance of TiO2-supported Re (Re/TiO2) catalysts for selective hydrogenation of carboxylic acid derivatives have been investigated. Re/TiO2 promotes selective hydrogenation reactions of carboxylic acids and esters that form the corresponding alcohols, and of amides that generate the corresponding amines. These processes are not accompanied by reduction of aromatic moieties. A Re loading amount of 5 wt% and a catalyst pretreatment with H-2 at 500 degrees C were identified as being optimal to obtain the highest catalytic activity for the hydrogenation processes. The results of studies using various characterization methods, including X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM), indicate that the Re species responsible for the catalytic hydrogenation processes have sub-nanometer to a few nanometer sizes and average oxidation states higher than 0 and below +4. The presence of either a carboxylic acid and/or its corresponding alcohol is critical for preventing the Re/TiO2 catalyst from promoting production of dearomatized byproducts. Although Re/TiO2 is intrinsically capable of hydrogenating aromatic rings, carboxylic acids, alcohols, amides, and amines strongly adsorb on the Re species, which leads to suppression of this process. Moreover, the developed catalytic system was applied to selective hydrogenation of triglycerides that form the corresponding alcohols.
    研究論文(学術雑誌), 英語
  • Metamorphosis-like Transformation during Activation of In/SiO2 Catalyst for Non-oxidative Coupling of Methane: In Situ X-ray Absorption Fine Structure Analysis
    Kashaboina Upendar; Nishikawa Yuta; Wakisaka Yuki; Sirisit Natee; Nagamatsu Shin-ichi; Bao Deling; Ariga-Miwa Hiroko; Takakusagi Satoru; Inami Yuta; Kuriyama Fumiya; Dipu Arnoldus Lambertus; Ogihara Hitoshi; Iguchi Shoji; Yamanaka Ichiro; Wada Takahiro; Asakura Kiyotaka
    CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 48巻, 9号, 掲載ページ 1145-1147, 出版日 2019年09月, 査読付, The local structure of In/SiO2, which is a potential catalyst for the non-oxidative coupling of methane, was investigated by using in situ In K-edge X-ray absorption fine-structure analysis. During the activation process, the In/SiO2 catalyst underwent several metamorphosis-like transformations of its structure before final conversion to the active phase.
    研究論文(学術雑誌), 英語
  • Improved synthesis of monocationic mu-nitrido-bridged iron phthalocyanine dimer with no peripheral substituents
    Yamada Yasuyuki; Sugiura Takuya; Morita Kentaro; Ariga-Miwa Hiroko; Tanaka Kentaro
    INORGANICA CHIMICA ACTA, ELSEVIER SCIENCE SA, 489巻, 掲載ページ 160-163, 出版日 2019年04月01日, 査読付, mu-Nitrido-bridged iron phthalocyanine dimers have attracted considerable attention because of their catalytic ability in alkane oxidation. However, clear and practical synthetic procedures for the simplest mu-nitrido-bridged iron phthalocyanine dimer with no peripheral substituents have not been reported because of its low solubility. In this study, we report improved synthesis and spectroscopic identification of the monocationic species of mu-nitrido-bridged iron phthalocyanine dimers that has no peripheral substituent groups. We observed that the use of iodine as an oxidant for the mu-nitrido-bridged iron phthalocyanine dimer prevents over-oxidation. Pyridine can dissolve its 1e(-)-oxidized monocationic species, which was characterized by H-1 NMR, C-13 NMR, IR, and UV spectroscopy as well as cyclic voltammetry.
    研究論文(学術雑誌), 英語
  • Evidence for Multi-Atom Resonance X-ray Raman Spectroscopy-An in situ Low Z-element and Bond-specific X-ray Spectroscopy
    Sirisit Natee; Kido Daiki; Wakisaka Yuki; Ariga-Miwa Hiroko; Takakusagi Satoru; Asakura Kiyotaka; Sekizawa Oki; Sakata Tomohiro; Uruga Tomoya; Iwasawa Yasuhiro
    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY, Surface Science Society Japan, 16巻, 掲載ページ 387-390, 出版日 2018年09月01日, 査読付
    研究論文(学術雑誌)
  • Reaction Stoichiometry and Mechanism of Pt Deposition via Surface Limited Redox Replacement of Copper UPD Layer on Au(111)
    Yuan Qiuyi; Wakisakai Yuki; Uemura Yohei; Wada Takahiro; Ariga-Miwa Hiroko; Takakusagi Satoru; Asakura Kiyotaka; Brankovic Stanko R
    JOURNAL OF PHYSICAL CHEMISTRY C, AMER CHEMICAL SOC, 122巻, 29号, 掲載ページ 16664-16673, 出版日 2018年07月26日, 査読付, The stoichiometry and reaction mechanism of Pt deposition via surface limited redox replacement (SLRR) of Cu underpotential-deposited (UPD) monolayer on Au(111) was studied using in situ polarization dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS), scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). We proposed that Pt deposition via SLRR of Cu UPD monolayer leads to formation/deposition of Pt-surface species mainly consisting of Pt(II) chloride with a square planar local structure [PtCl4] parallel to the Au surface (60%) which has a strong interaction of the Pt complex with the Au substrate. The rest (40%) was one-monolayer Pt metal cluster. This result provides a new understanding into the mechanism and stoichiometry of the SLRR reaction, which has a wide application for synthesis of monolayer catalysts.
    研究論文(学術雑誌), 英語
  • Phosphorous Diffusion Through Ni2P - Low Energy Diffusion Path and Its Unique Local Structure
    José Contreras-Mora; Hiroko Ariga-Miwa; Satoru Takakusagi; Christopher T. Williams; Kiyotaka Asakura
    Journal of Physical Chemistry C, American Chemical Society, 122巻, 11号, 掲載ページ 6318-6322, 出版日 2018年03月22日, 査読付, Phosphorous (P) diffusion in bulk Ni2P was investigated by the density functional theory (DFT) to find the origin of the lowerature P diffusion into the surface. The Ni2P bulk structure consists of two types of layers, Ni3P2 and Ni3P1, stacked along the [0001] direction. Two types of P vacancies in Ni2P were studied: V1 P (P deficient in N3P2) and V2 P (P deficient in N3P1). V1 P was a slightly more stable point defect than V2 P by 0.20 eV. The P diffusions to vacancies (V1 P and V2 P) had large diffusion barriers of more than 1 eV, except the P diffusion path along the [0001] direction through an interstitial site in Ni3P1 (I1→2 P) and then to V1 P, which showed the lowest energy barrier of about 0.18 eV. The DFT calculations suggested that the two adjacent vacancies (both V1 P) allow the local rearrangement of the structure to form a tetrahedral structure at the intermediate state. We have proposed a new diffusion mechanism in the intermetallic compound named the interstitial-vacancy diffusion mechanism.
    研究論文(学術雑誌), 英語
  • Smooth epitaxial copper film on sapphire surface suitable for high quality graphene growth
    Tao Ma; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    Thin Solid Films, Elsevier B.V., 646巻, 掲載ページ 12-16, 出版日 2018年01月31日, 査読付, Graphene, a two-dimensional material, can be grown on a metal substrate using chemical vapor deposition — this growth process is notably influenced by the crystal orientation and the roughness of the substrate surface. We prepared epitaxial Cu(111) films on sapphire substrates using thermal evaporation at various substrate temperatures and studied their crystal orientation and roughness. The well crystallized Cu(111) film with a smooth surface was obtained when the substrate was maintained at 473 K during the deposition. High quality graphene with few intrinsic defects was grown on this Cu film.
    研究論文(学術雑誌), 英語
  • Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H-2 and CO2
    Takashi Toyao; S. M. A. H. Siddiki; Yoshitsugu Morita; Takashi Kamachi; Abeda S. Touchy; Wataru Onodera; Kenichi Kon; Shinya Furukawa; Hiroko Ariga; Kiyotaka Asakura; Kazunari Yoshizawa; Ken-ichi Shimizu
    CHEMISTRY-A EUROPEAN JOURNAL, WILEY-V C H VERLAG GMBH, 23巻, 59号, 掲載ページ 14848-14859, 出版日 2017年10月, 査読付, Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H-2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (p(H2)=5 MPa, T=180 degrees C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.
    研究論文(学術雑誌), 英語
  • Controlling the inhomogeneity of solid catalysts at the mesoscopic scale
    Hua Huang; Takahiro Wada; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura; Yasuhiro Iwasawa
    CHEMICAL PHYSICS LETTERS, ELSEVIER SCIENCE BV, 683巻, 掲載ページ 18-21, 出版日 2017年09月, 査読付, High-performance catalysts are often composed of two or more active phases, which are believed to interact with each other at the mesoscopic scale structure. Unlike conventional powder catalysts flat surfaces is advantageous in that its surface structure can be precisely designed. We prepared precisely designed Sb2O4/VSbO4/Si catalysts containing Sb2O4 ribbons with finely controlled width and separation by electron lithography. We demonstrated that the acrolein generation rate on the catalysts was related to the width and separation of the Sb2O4 ribbons. This work shows the possibility to regulate catalyses by inhomogeneity of the surface structure at the mesoscopic level. (C) 2017 Elsevier B.V. All rights reserved.
    研究論文(学術雑誌), 英語
  • Polarization-dependent Total Reflection Fluorescence X-ray Absorption Fine Structure (PTRF-XAFS) Studies on the Structure of a Pt Monolayer on Au(111) Prepared by the Surface-limited Redox Replacement Reaction
    Qiuyi Yuan; Satoru Takakusagi; Yuki Wakisaka; Yohei Uemura; Takahiro Wada; Hiroko Ariga; Kiyotaka Asakura
    CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 46巻, 8号, 掲載ページ 1250-1253, 出版日 2017年08月, 査読付, We studied the initial stage of a Pt monolayer produced by surface-limited redox replacement (SLRR) using polarization-dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS). Different from the widely accepted understanding that metallic monolayer islands are formed, our XAFS showed that the Pt monolayer, initially present on the Au(111) substrate, was mainly in the form of a planar [PtCl4](2-) complex with its molecular plane parallel to Au(111). This result provides a new insight into the mechanism of SLRR.
    研究論文(学術雑誌), 英語
  • Promotional Effect of Water on Direct Dimethyl Ether Synthesis from Carbon Monoxide and Hydrogen Catalyzed by Cu−Zn/Al2O3
    Kaoru Takeishi; Yutaro Wagatsuma; Hiroko Ariga; Kenichi Kon; Ken-ichi Shimizu
    ACS Sustainable Chemistry & Engineering, 5巻, 掲載ページ 3675-3680, 出版日 2017年03月, 査読付
    研究論文(学術雑誌), 英語
  • A New Indicator for Single Metal Dispersion on a TiO2(110) Surface Premodified with a Mercapto Compound
    Satoru Takakusagi; Akitoshi Kunimoto; Natee Sirisit; Hiromitsu Uehara; Tadashi Ohba; Yohei Uemuara; Takahiro Wada; Hiroko Ariga; Wang-Jae Chun; Yasuhiro Iwasawa; Kiyotaka Asakura
    JOURNAL OF PHYSICAL CHEMISTRY C, AMER CHEMICAL SOC, 120巻, 29号, 掲載ページ 15785-15791, 出版日 2016年07月, 査読付, Ni and Pt structures evaporated onto a TiO2(110) surface premodified with ortho-mercaptobenzoic acid (o-MBA) were studied using polarization-dependent total reflection fluorescence X-ray absorption fine structure analysis to determine the effects of the premodification on the dispersion of the metal atoms over the TiO2(110) surface. Ni was found to be atomically dispersed with the formation of S-Ni-O bonds (where the S is provided by the o-MBA and the 0 is present in the TiO2 lattice) on the surface. In contrast, Pt underwent aggregation to form small clusters. The varying behavior of these metals on the o-MBA-modified TiO2(110) surface is discussed based on the energy difference between sulfur-metal-oxygen and metal-metal bond formations, and we propose a new indicator for single metal dispersion on the TiO2(110) surface.
    研究論文(学術雑誌), 英語
  • In Situ X-ray Absorption Fine Structure Analysis of PtCo, PtCu, and PtNi Alloy Electrocatalysts: The Correlation of Enhanced Oxygen Reduction Reaction Activity and Structure
    Takahiro Kaito; Hiroyuki Tanaka; Hisashi Mitsumoto; Seiho Sugawara; Kazuhiko Shinohara; Hiroko Ariga; Hiromitsu Uehara; Satoru Takakusagi; Kiyotaka Asakura
    JOURNAL OF PHYSICAL CHEMISTRY C, AMER CHEMICAL SOC, 120巻, 21号, 掲載ページ 11519-11527, 出版日 2016年06月, 査読付, In order to examine the relationship between the oxygen reduction reaction (ORR) activity of a fuel cell catalyst and its structure and/or electronic state, carbon-supported Pt and Pt alloys having various structures, compositions, and morphologies were studied. Regardless of the atomic ordering or morphology (core-shell or random alloy) of the catalyst, the ORR activity was primarily dependent on the Pt-Pt bond distance. Among these materials, Pt2Co, having the shortest Pt-Pt distance, exhibited the highest ORR activity. The activities of this catalyst per unit surface. area and per unit mass were approximately 10 times and 6 times higher than those of a commercially available carbon supported Pt electrocatalyst (Pt/C). This work also found a monotonic increase in catalytic activity with decreasing Pt-Pt distance.
    研究論文(学術雑誌), 英語
  • Structure determination of the rutile-TiO2(110)-(1 x 2) surface using total-reflection high-energy positron diffraction (TRHEPD)
    I. Mochizuki; H. Ariga; Y. Fukaya; K. Wada; M. Maekawa; A. Kawasuso; T. Shidara; K. Asakura; T. Hyodo
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS, ROYAL SOC CHEMISTRY, 18巻, 10号, 掲載ページ 7085-7092, 出版日 2016年03月, 査読付, The exact structure of the rutile-TiO2(110)-(1 x 2) surface, which had been under debate over the past 30 years, was investigated using the newly developed technique of total-reflection high-energy positron diffraction (TRHEPD), which is a positron counterpart of reflection high-energy electron diffraction (RHEED). The rocking-curves for the 00-spot obtained from the experimental diffraction patterns were compared to the curves for various models calculated with a full-dynamical theory. It was found that the rocking-curves matched those for a surface consisting of a Ti2O3 configuration, originally suggested by Onishi and Iwasawa [H. Onishi and Y. Iwasawa, Surf. Sci., 1994, 313, L783], but with a further modification of atomic positions close to the ones proposed by Wang et al. [Q. Wang, A. R. Oganov, Q. Zhu and X. F. Zhou, Phys. Rev. Lett., 2014, 113, 266101]. This result demonstrates that TRHEPD can distinguish between the existence and absence of the oxygen atoms on the topmost surface, and between the Ti atoms residing in positions at the interstitial-vertical sites and those at interstitial-horizontal sites.
    研究論文(学術雑誌), 英語
  • 19aAR-4 全反射高速陽電子回折(TRHEPD)によるルチル型チタニア(110)(1×2)表面の構造決定
    望月 出海; 有賀 寛子; 深谷 有喜; 和田 健; 一宮 彪彦; 朝倉 清高; 兵頭 俊夫
    日本物理学会講演概要集, 一般社団法人日本物理学会, 71巻, 掲載ページ 2483-2483, 出版日 2016年
    日本語
  • KEK物構研低速陽電子実験施設における全反射高速陽電子回折(TRHEPD)の最近の成果
    兵頭 俊夫; 望月 出海; 一宮 彪彦; 設楽 哲夫; 深谷 有喜; 圓谷 志郎; 境 誠司; 社本 真一; 和田 健; 前川 雅樹; 河裾 厚男; 有賀 寛子; 朝倉 清高
    表面科学学術講演会要旨集, 公益社団法人 日本表面科学会, 36巻, 掲載ページ 244-244, 出版日 2016年, 表面の原子配置に超敏感な全反射高速陽電子回折(TRHEPD)の特徴と、KEK物構研低速陽電子実験施設のTRHEPDステーションの最近の成果、特にルチル型TiO2(110)(1×2)の表面構造決定、およびCu(111)面上とCo(0001)面上のグラフェンの構造(バックリングの有無と、基板との距離)の決定について報告する。
    日本語
  • 全反射高速陽電子回折(TRHEPD)法によるルチル型TiO2(110)(1×2)表面の構造決定
    望月 出海; 有賀 寛子; 深谷 有喜; 和田 健; 前川 雅樹; 河裾 厚男; 設楽 哲夫; 朝倉 清高; 兵頭 俊夫
    表面科学, 公益社団法人 日本表面科学会, 37巻, 9号, 掲載ページ 451-456, 出版日 2016年,

    The detailed structure of the rutile-TiO2(110)(1×2) surface, which had been under debate for the past 30 years, was investigated using the newly developed technique of total-reflection high-energy positron diffraction (TRHEPD), which is a positron counterpart of reflection high-energy electron diffraction (RHEED). The rocking curves for the 00 spot extracted from the experimental diffraction patterns were compared with the curves for various models calculated using a full-dynamical diffraction theory. The rocking curves matched those for a surface consisting of a Ti2O3 composition, originally suggested by Onishi and Iwasawa [H. Onishi and Y. Iwasawa. Surf. Sci. 313, L783 (1994)], but with a further modification of atomic positions close to the ones proposed by Wang et al. [Q. Wang, A. R. Oganov, Q. Zhu and X. F. Zhou, Phys. Rev. Lett. 113, 266101 (2014)].


    日本語
  • Investigation of the Cleanliness of Transferred Graphene: The First Step toward Its Application as a Window Material for Electron Microscopy and Spectroscopy
    Tao Ma; Kotaro Miyazaki; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, CHEMICAL SOC JAPAN, 88巻, 8号, 掲載ページ 1029-1035, 出版日 2015年08月, 査読付, The cleanliness of transferred graphene is of significant importance for its application as the window material in environmental cells used for electron microscopy and spectroscopy. We investigated the dependence of the cleanliness of graphene on transfer routes, including FeCl3 etching, (NH4)(2)S2O8 etching, electrochemical delamination, and O(2-)bubbling, by means of transmission electron microscopy and X-ray photoelectron spectroscopy. It was found that electrochemical delamination provided the cleanest graphene with only a small amount of poly(methyl methacrylate) (PMMA) residue existing on the surface.
    研究論文(学術雑誌), 英語
  • Ultrathin inorganic molecular nanowire based on polyoxometalates
    Zhenxin Zhang; Toru Murayama; Masahiro Sadakane; Hiroko Ariga; Nobuhiro Yasuda; Norihito Sakaguchi; Kiyotaka Asakura; Wataru Ueda
    NATURE COMMUNICATIONS, NATURE PUBLISHING GROUP, 6巻, 出版日 2015年07月, 査読付, The development of metal oxide-based molecular wires is important for fundamental research and potential practical applications. However, examples of these materials are rare. Here we report an all-inorganic transition metal oxide molecular wire prepared by disassembly of larger crystals. The wires are comprised of molybdenum(VI) with either tellurium(IV) or selenium(IV): {(NH4)(2)[XMo6O21]}(n) (X = tellurium(IV) or selenium(IV)). The ultrathin molecular nanowires with widths of 1.2 nm grow to micrometre-scale crystals and are characterized by single-crystal X-ray analysis, Rietveld analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, thermal analysis and elemental analysis. The crystals can be disassembled into individual molecular wires through cation exchange and subsequent ultrasound treatment, as visualized by atomic force microscopy and transmission electron microscopy. The ultrathin molecular wire-based material exhibits high activity as an acid catalyst, and the band gap of the molecular wire-based crystal is tunable by heat treatment.
    研究論文(学術雑誌), 英語
  • Exploring the catalytic properties of supported palladium catalysts in the transfer hydrogenolysis of glycerol
    F. Mauriello; H. Ariga; M. G. Musolino; R. Pietropaolo; S. Takakusagi; K. Asakura
    APPLIED CATALYSIS B-ENVIRONMENTAL, ELSEVIER SCIENCE BV, 166巻, 掲載ページ 121-131, 出版日 2015年05月, 査読付, The transfer hydrogenolysis of glycerol promoted by supported palladium catalysts is reported. The reactions were carried out under mild conditions (453K and 5 bar of N-2) in absence of added hydrogen by using the reaction solvent, 2-propanol, as hydrogen source. The catalytic results are interpreted in terms of metal (Pd)-metal (Co or Fe) interaction that modifies the electronic properties of palladium and affords bimetallic PdM sites (M= Co or Fe), thus enhancing the catalytic properties of the systems in the conversion of glycerol as well as in the selectivity to 1,2-propanediol and 1-propanol. The transfer hydrogenolysis mechanism is here elucidated and involves the glycerol dehydration to 1-hydroxyacetone and the subsequent hydrogenation of 1-hydroxyacetone to propylene glycol. (C) 2014 Elsevier B.V. All rights reserved.
    研究論文(学術雑誌), 英語
  • An Investigation of Ni2P Single Crystal Surfaces: Structure, Electronic State and Reactivity
    Qiuyi Yuan; Hiroko Ariga; Kiyotaka Asakura
    TOPICS IN CATALYSIS, SPRINGER/PLENUM PUBLISHERS, 58巻, 4-6号, 掲載ページ 194-200, 出版日 2015年04月, 査読付, Ni2P has demonstrated high catalytic activity for hydrodesulfurization and has recently been employed as a catalyst in a variety of other reactions. We have thoroughly reviewed the literature concerning Ni2P single crystal surfaces, with the aim of determining the relationship between surface structure and catalytic properties. Published results to date indicate that Ni2P single crystal surfaces exhibit reconstructed structures, and so the bulk terminated structure may not be stable. We have also reviewed the surface structures and electronic states of (1 x 1) and reconstructed Ni2P(0001) and (). Based on these reviews, this paper presents general rules regarding stabilization of the Ni2P surface structure and discusses the role of phosphorus in the single crystal surfaces.
    研究論文(学術雑誌), 英語
  • A high-temperature in situ cell with a large solid angle for fluorescence X-ray absorption fine structure measurement
    Naoyoshi Murata; Makoto Kobayashi; Yukari Okada; Takuya Suzuki; Hiroaki Nitani; Yasuhiro Niwa; Hitoshi Abe; Takahiro Wada; Shingo Mukai; Hiromitsu Uehara; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    REVIEW OF SCIENTIFIC INSTRUMENTS, AMER INST PHYSICS, 86巻, 3号, 掲載ページ 034102, 出版日 2015年03月, 査読付, We present the design and performance of a high-temperature in situ cell with a large solid angle for fluorescence X-ray absorption fine structure (XAFS) spectra. The cell has a large fluorescence XAFS window (116 mm(phi)) near the sample in the cell, realizing a large half-cone angle of 56 degrees. We use a small heater (25 x 35 mm(2)) to heat the sample locally to 873 K. We measured a Pt-SnO2 thin layer on a Si substrate at reaction conditions having a high activity. In situ measurement enables the analysis of the difference XAFS spectra between before and during the reaction to reveal the structure change during the operation. (C) 2015 AIP Publishing LLC.
    研究論文(学術雑誌), 英語
  • 19aPS-111 Nb-doped TiO_2基板の電気伝導性の第一原理計算
    大濱 彰博; 石井 晃; 有賀 寛子; 朝倉 清高
    日本物理学会講演概要集, 一般社団法人日本物理学会, 70巻, 掲載ページ 1463-1463, 出版日 2015年
    日本語
  • Temperature dependence study of NO oxidation of Ni2P(10-10) surface
    Yuan Qiuyi; Ariga Hiroko; Asakura Kiyotaka
    表面科学学術講演会要旨集, 公益社団法人 日本表面科学会, 35巻, 掲載ページ 147-147, 出版日 2015年, The reconstructed Ni2P(10-10) c(2X4) surface can be oxidized by NO. But the resultant structure and its temperature dependency remain unclear. We studied NO oxidation of Ni2P(10-10) surface by scanning tunneling microscope, X-ray photoelectron spectroscopy and low-energy electron diffraction. The phosphorus rich c(2X4) covered surface converted into uncovered (1X1) surface after NO dosing. The reaction rate of NO oxidation can be tuned by controlling dosing temperature. The higher temperature gives a faster reaction rate and a higher coverage of c(2X4) after NO dosing.
  • Electrodeposition Study on a Single-crystal Titanium Dioxide Electrode: Platinum on a Niobium-doped Titanium Dioxide(110) Electrode
    Satoru Takakusagi; Takafumi Ogawa; Hiromitsu Uehara; Hiroko Ariga; Ken-ichi Shimizu; Kiyotaka Asakura
    CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 43巻, 11号, 掲載ページ 1797-1799, 出版日 2014年11月, Pt was successfully electrodeposited on a Nb-doped TiO2(110) electrode from a solution of 1 mM K-2[PtCl4] and 50 mM H2SO4 using single-pulse chronoamperometry. The morphology of the deposited Pt nanoparticles was sensitive to the deposition potential and holding time. A novel method for the preparation of metal particles on a single-crystal TiO2 surface in a controlled manner has been proposed.
    研究論文(学術雑誌), 英語
  • STMによるNi2P(101b0)単結晶表面のNOとの反応性評価
    鴻野健太郎; 有賀寛子; 高草木達; 大谷茂樹; 朝倉清高
    表面科学, 35巻, 8号, 掲載ページ 415-419, 出版日 2014年08月, 査読付, 招待
    研究論文(学術雑誌), 日本語
  • A new spectroelectrochemical cell for in situ measurement of Pt and Au K-edge X-ray absorption fine structure
    Takahiro Kaito; Hisashi Mitsumoto; Seiho Sugawara; Kazuhiko Shinohara; Hiromitsu Uehara; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    REVIEW OF SCIENTIFIC INSTRUMENTS, AMER INST PHYSICS, 85巻, 8号, 掲載ページ 084104, 出版日 2014年08月, 査読付, A new spectroelectrochemical cell to investigate the structure of Pt/Au nanoclusters using Pt and Au K-edge X-ray absorption fine structure (XAFS) measurements under the electrochemical conditions is developed. K-edge XAFS measurements for Pt and Au require a sample as thick as 1-2 cm, which prevents homogeneous potential distribution. We can measure in situ Pt and Au K-edge XAFS spectra and determine reasonable electrochemical surface areas using our developed spectroelectrochemical cell. This work provides a new approach to analyze Pt/Au core-shell nanoclusters. The new cell is designed to be applied to both spectra with high absorption-edge energies such as the K-edge of Pt and Au and those with low absorption-edge energy such as Pt L-edge. (C) 2014 AIP Publishing LLC.
    研究論文(学術雑誌), 英語
  • Micro reverse monte carlo approach to EXAFS analysis
    Keisuke Fujikawa; Hiroko Ariga; Satoru Takakusagi; Hiromitsu Uehara; Tadashi Ohba; Kiyotaka Asakura
    e-Journal of Surface Science and Nanotechnology, Surface Science Society of Japan, 12巻, 掲載ページ 322-329, 出版日 2014年07月05日, 査読付, We have developed a new Reverse Monte Carlo code, called the micro Reverse Monte Carlo (m-RMC), which is applicable to structure analysis of nanomaterials and surface species. In the m-RMC, Reverse Monte Carlo is applied to an ensemble of replica files, each of which contains one molecule or one small cluster, because the Extended X-ray Absorption Fine Structure (EXAFS) is sensitive to short-range structures and has negligible interaction between molecules or clusters. We apply the m-RMC to face-centered cubic metals (Cu, Pd, and Pt) and discuss the advantages, validation, and problems of the m-RMC. The bond distance and some cumulant coefficients can be determined from the EXAFS using m-RMC. Some 50-100 replica files are sufficient to reproduce the EXAFS oscillations and radial distributions. The bond distance can be determined, including the asymmetric distributions, by m-RMC. We also apply m-RMC to α-MoO 3 and Au clusters. The m-RMC analysis of MoO3 shows that three radial distribution peaks appear corresponding to three types of Mo-O bonds. The m-RMC analysis of Au cluster indicates the presence of Au 55 cuboctahedral structure with Au-Au distance at 0.288 nm. We obtain a 3 D image of Au55 nanocluster from the unified file. The m-RMC method can be applied to the analysis of the EXAFS for chemical systems with appropriate care. © 2014 The Surface Science Society of Japan.
    研究論文(学術雑誌), 英語
  • Pt-Promoted Cu/SBA-15 Catalysts with Excellent Performance for Chemoselective Hydrogenation of Dimethyl Oxalate to Ethylene Glycol
    Xinlei Zheng; Haiqiang Lin; Jianwei Zheng; Hiroko Ariga; Kiyotaka Asakura; Youzhu Yuan
    TOPICS IN CATALYSIS, SPRINGER/PLENUM PUBLISHERS, 57巻, 10-13号, 掲載ページ 1015-1025, 出版日 2014年06月, Cu/SBA-15 catalysts containing a small amount of Pt (Cu-Pt/SBA-15) were prepared by sequential adsorption-reduction method and examined for chemoselective hydrogenation of dimethyl oxalate(DMO) to ethylene glycol (EG). The Cu-Pt/SBA-15 catalyst with an optimal Cu/Pt atomic ratio of 10 showed a DMO conversion close to 100 % with a 98 % selectivity to EG at a temperature as low as 463 K. The results showed that the best Cu-Pt/SBA-15 enhanced the space time yield of EG by about 1.47 times compared with Cu/SBA-15. The introduction of Pt with stronger ability for H-2 adsorption and activation substantially enhanced the reducibility of the Cu2+ species and further promoted the chemisorption capacity of H-2. After reduction, a portion of Cu was alloyed with Pt, which was beneficial for the generation and stabilization of a balanced Cu+/Cu-0 ratio during the hydrogenation process.
    研究論文(学術雑誌), 英語
  • K-Edge X-ray Absorption Fine Structure Analysis of Pt/Au Core-Shell Electrocatalyst: Evidence for Short Pt-Pt Distance
    Takahiro Kaito; Hisashi Mitsumoto; Seiho Sugawara; Kazuhiko Shinohara; Hiromitsu Uehara; Hiroko Ariga; Satoru Takakusagi; Yoshikiyo Hatakeyama; Keiko Nishikawa; Kiyotaka Asakura
    JOURNAL OF PHYSICAL CHEMISTRY C, AMER CHEMICAL SOC, 118巻, 16号, 掲載ページ 8481-8490, 出版日 2014年04月, A carbon-supported Pt-shell Au-core electrocatalyst (Pt/Au/C) was prepared by sequential deposition of Pt ions on the surface of Au nanoparticles supported on carbon. The area-specific activity of the oxygen reduction reaction (ORR) for the prepared Pt/Au/C in 0.1 M HClO4, aqueous solution was approximately 2 times higher than that for a commercial carbon-supported Pt electrocatalyst (Pt/C). The core-shell structure was confirmed using electrochemical methods and Pt and Au K-edge X-ray absorption fine structure (XAFS) analysis. XAFS analyses indicated that the Pt-Pt bond distance for the Pt/Au/C catalyst was shorter than that for Pt foil and the Pt/C catalyst. In addition, the Au Au distance was much shorter than that for Au foil. The reason for the high ORR activity of Pt/Au/C is considered to be shorter Pt-Pt bond distance as compared to that of Pt/C.
    研究論文(学術雑誌), 英語
  • Atomic structure and catalytic activity of W-modified Ni2P surface alloy by photoelectron diffraction and spectroscopy
    Hirosuke Matsui; Fumihiko Matsui; Naoyuki Maejima; Hiroshi Daimon; Tomohiro Matsushita; Hiroko Ariga; Kiyotaka Asakura
    e-Journal of Surface Science and Nanotechnology, 12巻, 掲載ページ 53-56, 出版日 2014年02月20日, The surface alloying is the important topics in Ni2P study which is expected for next generation hydrodesulfurization and hydrodenitrogenation catalyst. The atomic structure and catalytic properties of a single crystalline Ni2P surface modified with W (W-Ni2P) was investigated by photoelectron diffraction (PED) and spectroscopy. PED is an element and site selective surface structure analysis method that enables observation of three-dimensional atomic configurations of the surface local structure. The selective replacement of W to the Ni site in the Ni2P crystal was clarified by PED. Chemical reactivities for NO molecules of the W-Ni 2P and the clean Ni2P surfaces were compared. On the clean Ni2P surface, the NO adsorption did not occur, whereas W-Ni 2P surface showed remarkable activity for NO adsorption. © 2014 The Surface Science Society of Japan.
    研究論文(学術雑誌), 英語
  • Muonium response to oxygen content in biological aqueous solutixons for cancer research
    A. D. Pant; K. Nagamine; I. Shiraki; E. Torikai; K. Shimomura; F. L. Pratt; H. Ariga; K. Ishida; J. S. Schultz
    13TH INTERNATIONAL CONFERENCE ON MUON SPIN ROTATION, RELAXATION AND RESONANCE, IOP PUBLISHING LTD, 551巻, 掲載ページ 012043, 出版日 2014年, 査読付, Muonium (Mu), which is known to exhibit a characteristic concentration dependent spin relaxation change when impacting molecular oxygen dissolved in water, was found to show a similar behaviour in aqueous solutions of Tris Buffered Saline (TBS), albumin, serum, and hemoglobin (Hb). These effects, along with the interaction of Mu with deoxy-Hb (which is modulated by oxygen by the formation of oxy-Hb) suggest that the muon method can be applied to systematic studies of oxygen dependent effects in biological systems. This muon method may particularly be applicable at low (hypoxic) oxygen levels, an important consideration in the radiation treatment of cancer.
    研究論文(国際会議プロシーディングス), 英語
  • Detection of oxygen vacancy in rutile TiO2 single crystal by μSR measurement.
    朝倉 清高
    JPS Conference Proceedings., 2巻, 掲載ページ 010307, 出版日 2014年, 査読付
    研究論文(学術雑誌), 英語
  • Efficient Ru-Fe catalyzed selective hydrogenolysis of carboxylic acids to alcoholic chemicals
    Wenjing Li; Linmin Ye; Pei Long; Jin Chen; Hiroko Ariga; Kiyotaka Asakura; Youzhu Yuan
    RSC ADVANCES, ROYAL SOC CHEMISTRY, 4巻, 55号, 掲載ページ 29072-29082, 出版日 2014年, Supported bimetallic Ru-Fe catalysts were prepared using a step-deposition-reduction method. The selective hydrogenolysis of acetic acid to ethanol was investigated as a reaction, which is considered to be related to the transformation of biomass-derived carboxylic acids to fuels and value-added chemicals. An SBA-15-supported Ru-Fe catalyst displayed significant improvements in catalytic performance for the hydrogenolysis of acetic acid to ethanol compared with monometallic catalysts and that with SiO2 as a carrier. When the Ru/Fe atomic ratio was set at 2/1, the prepared catalyst could give a nearly 100% conversion of acetic acid and 88% selectivity to ethanol. The catalyst showed considerable stability in terms of structure and performance for a long-term run on stream. Characterization results indicated that a small portion of Fe species was alloyed with Ru, whereas the other portion of Fe species, likely FeO1+x (0 < x < 0.5), was dispersed on the catalyst surfaces. The Fe species were crucial for the stabilization of Ru-Fe bimetallic nanoparticles and activation of acetic acid molecules in the hydrogenolysis reaction. Moreover, several other carboxylic acids, such as propionic acid, levulinic acid, and lactic acid, could also be efficiently converted to their corresponding alcoholic chemicals or lactone using the optimized Ru-Fe/SBA-15 catalyst under relatively mild conditions.
    研究論文(学術雑誌), 英語
  • Density Function Theoretical Investigation on the Ni3PP Structure and the Hydrogen Adsorption Property of the Ni2P(0001) Surface
    Hiroko Ariga; Mayumi Kawashima; Satoru Takakusagi; Kiyotaka Asakura
    CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 42巻, 12号, 掲載ページ 1481-1483, 出版日 2013年12月, The electronic and structural properties of a phosphorus-terminated structure of Ni2P(0001) surface (Ni3PP) are investigated by density functional theory (DFT) calculations. Phosphorus adsorption largely stabilizes the Ni2P(0001) surface by creating Ni-P bonds on the Ni trimer. Atomic hydrogen can adsorb on the topmost P site although its adsorption energy is much lower than its adsorption energy on the Ni trimer site of the Ni3P2 surface. Our results suggest that the Ni trimer is the key factor for high catalytic activity.
    研究論文(学術雑誌), 英語
  • Anisotropic growth of a nickel trimer formed on a highly-stepped TiO2(110) surface
    Hiromitsu Uehara; Muhammad Haneef Bin Hanaffi; Yuichiro Koike; Keisuke Fujikawa; Shushi Suzuki; Hiroko Ariga; Satoru Takakusagi; Wang-Jae Chun; Yasuhiro Iwasawa; Kiyotaka Asakura
    CHEMICAL PHYSICS LETTERS, ELSEVIER SCIENCE BV, 570巻, 掲載ページ 64-69, 出版日 2013年05月, The structures of Ni clusters formed on a highly-stepped TiO2(110) surface were studied by polarization-dependent total reflection fluorescence X-ray absorption fine structure analysis. When 0.8 monolayers of Ni were deposited, three-dimensional Ni clusters with 1-2 nm diameters and heights less than 1 nm were formed. Conversely, when 0.07 monolayers of Ni were deposited, an anisotropic Ni trimer with a Ni-Ni distance of 0.260 nm was created at the [001] step. We revealed that the surface modification to enhance the metal-anion interaction can control the deposited metal structure. (C) 2013 Elsevier B.V. All rights reserved.
    研究論文(学術雑誌), 英語
  • Fine tuning and orientation control of surface Cu complexes on TiO2(110) premodified with mercapto compounds: the effect of different mercapto group positions
    Satoru Takakusagi; Hirotaka Nojima; Hiroko Ariga; Hiromitsu Uehara; Kotaro Miyazaki; Wang-Jae Chun; Yasuhiro Iwasawa; Kiyotaka Asakura
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS, ROYAL SOC CHEMISTRY, 15巻, 33号, 掲載ページ 14080-14088, 出版日 2013年, 査読付, Three-dimensional structures of vacuum-deposited Cu species formed on TiO2(110) surfaces premodified with three mercaptobenzoic acid (MBA) isomers were studied using polarization-dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS). We explored the possibility of fine tuning and orientation control of the surface Cu structures, including their coordination and configuration against the surface, according to the different mercapto group positions of the three MBA isomers (o(-), m(-), and p-MBA). Almost linear S-Cu-O (lattice O of TiO2) surface compounds were formed on the three MBA-modified TiO2(110) surfaces; however, the orientation of the Cu species on the o- and m-MBA-modified TiO2(110) surfaces (40-45 degrees inclined from the surface normal) was different from that on the p-MBA-modified TiO2(110) surface (60 degrees from the surface normal). This work suggests that the selection of a different MBA isomer for premodification of a single crystal TiO2(110) surface enables fine tuning and orientation control of surface Cu complexes.
    研究論文(学術雑誌), 英語
  • Preparation and structure of a single Au atom on the TiO2(110) surface: control of the Au-metal oxide surface interaction
    Kiyotaka Asakura; Satoru Takakusagi; Hiroko Ariga; Wang-Jae Chun; Shushi Suzuki; Yuichiro Koike; Hiromitsu Uehara; Kotaro Miyazaki; Yasuhiro Iwasawa
    FARADAY DISCUSSIONS, ROYAL SOC CHEMISTRY, 162巻, 掲載ページ 165-177, 出版日 2013年, 査読付, Three-dimensional Au structures on bare and organic-compound-modified TiO2(110) surfaces were interrogated by Au L-3-edge polarization dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) spectroscopy. On the bare TiO2(110) surface, icosahedral Au-55 nanoclusters were the main product found. When the surfaces were modified with ortho or meso mercaptobenzoic acid (o-MBA or m-MBA), Au was atomically dispersed. Sulfur atoms in the o- and m-MBA formed strong covalent bonds with Au to produce stable Au-MBA (o-and m-forms) surface complexes. On the other hand, only oxygen atoms on the surface did not make a strong enough interaction to stabilize the Au species. We discuss how the Au species formed on the modified TiO2(110) surface and the possibility to control the Au structure by the surface modification method.
    研究論文(学術雑誌), 英語
  • Surface structure and chemical properties of Ni2P surfaces
    Ariga H; Miyamoto T; Takakusagi S; Otani S; Oyama TS; Asakura K
    Abstracts of Papers of the American Chemical Society, 246巻, 出版日 2013年, 査読付
  • Silver-modulated SiO2-supported copper catalysts for selective hydrogenation of dimethyl oxalate to ethylene glycol
    Ying Huang; Hiroko Ariga; Xinlei Zheng; Xinping Duan; Satoru Takakusagi; Kiyotaka Asakura; Youzhu Yuan
    Journal of Catalysis, 307巻, 掲載ページ 74-83, 出版日 2013年, We present the application of a one-step urea-assisted gelation method to prepare a SiO2-supported bimetallic catalyst composed of copper (Cu) and silver (Ag). Results show the remarkably enhanced performance of the catalyst for selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Coupled with a series of characterization and kinetic studies, the improved activity is attributed to the formation of Cu nanoparticles containing Ag nanoclusters on the SiO2 surface. The coherent interactions between the Cu and Ag species help create the active Cu+/Cu 0 species in a suitable proportion and prevent the transmigration of bimetallic nanoparticles during the hydrogenation process. The optimized CuAg/SiO2 catalyst with an Ag/Cu atomic ratio of 0.05 has a balanced Cu+/Cu0 ratio and highly dispersed bimetal particles, which account for its high turnover frequency, EG selectivity of 97.0%, and excellent catalytic stability during the hydrogenation of DMO to EG for longer than 150 h. © 2013 Elsevier Inc. All rights reserved.
    研究論文(学術雑誌), 英語
  • Surface science approach to catalyst preparation - Pd deposition onto thin Fe3O4(111) films from PdCl2 precursor
    Hui-Feng Wang; Hiroko Ariga; Rhys Dowler; Martin Sterrer; Hans-Joachim Freund
    JOURNAL OF CATALYSIS, ACADEMIC PRESS INC ELSEVIER SCIENCE, 286巻, 掲載ページ 1-5, 出版日 2012年02月, 査読付, In this work, we introduce a surface science approach to supported metal catalyst preparation utilizing thin, single-crystalline oxide films as substrates. The use of thin oxide films allows for combined morphological and chemical characterization of the sample at various steps of a typical catalyst preparation procedure. A Fe3O4-supported Pd model catalyst was prepared by impregnation of (FeO4)-O-3(1 1 1) films with acidic PdCl2 solution, and the transformation of the adsorbed precursor into supported Pd nanoparticles by stepwise heating in vacuum was followed with scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The results provide evidence for homogeneous nucleation of Pd particles out of a monolayer of adsorbed precursor and an enhancement of the particle-support interaction with increasing annealing temperature. Chlorine, which remains on the model catalyst surface after vacuum annealing, could be removed by oxidation/reduction. This treatment also leads to particle sintering with an increase in the average particle diameter from 2 nm to 4 nm after oxidation/reduction. (C) 2011 Elsevier Inc. All rights reserved.
    研究論文(学術雑誌), 英語
  • Surface science approach to catalyst preparation - Pd deposition onto thin Fe3O4(111) films from PdCl2 precursor
    Hui-Feng Wang; Hiroko Ariga; Rhys Dowler; Martin Sterrer; Hans-Joachim Freund
    JOURNAL OF CATALYSIS, ACADEMIC PRESS INC ELSEVIER SCIENCE, 286巻, 掲載ページ 1-5, 出版日 2012年02月, In this work, we introduce a surface science approach to supported metal catalyst preparation utilizing thin, single-crystalline oxide films as substrates. The use of thin oxide films allows for combined morphological and chemical characterization of the sample at various steps of a typical catalyst preparation procedure. A Fe3O4-supported Pd model catalyst was prepared by impregnation of (FeO4)-O-3(1 1 1) films with acidic PdCl2 solution, and the transformation of the adsorbed precursor into supported Pd nanoparticles by stepwise heating in vacuum was followed with scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The results provide evidence for homogeneous nucleation of Pd particles out of a monolayer of adsorbed precursor and an enhancement of the particle-support interaction with increasing annealing temperature. Chlorine, which remains on the model catalyst surface after vacuum annealing, could be removed by oxidation/reduction. This treatment also leads to particle sintering with an increase in the average particle diameter from 2 nm to 4 nm after oxidation/reduction. (C) 2011 Elsevier Inc. All rights reserved.
    研究論文(学術雑誌), 英語
  • Alkali-Metal-Promoted Pt/TiO2 Opens a More Efficient Pathway to Formaldehyde Oxidation at Ambient Temperatures
    Changbin Zhang; Fudong Liu; Yanping Zhai; Hiroko Ariga; Nan Yi; Yongchun Liu; Kiyotaka Asakura; Maria Flytzani-Stephanopoulos; Hong He
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, WILEY-V C H VERLAG GMBH, 51巻, 38号, 掲載ページ 9628-9632, 出版日 2012年, 査読付
    研究論文(学術雑誌), 英語
  • α-Sb2O4/VSbO4 触媒上精密構造制御と反応特性
    黄 華; 原口 惟; 和田 敬広; 有賀 寛子; 高草木 達; 朝倉 清高
    表面科学学術講演会要旨集, 公益社団法人 日本表面科学会, 32巻, 掲載ページ 113-113, 出版日 2012年, 電子線リソグラフィー法を用いてSb2O4の線幅や間隔を変化させた不均一規制αーSb2O4/VSbO4 触媒を調製し,プロピレンの部分酸化反応を調べた.アクロレンへの選択性がSb2O4のミクロレベルの構造により変化することを見出した.これをリモートコントロール機構で説明した.
  • Direct evidence for orientations in the amorphous functional polymer thin films deposited on Si surface
    Kiyotaka Aasakura; Takahiro Wada; Hiromitsu Uehara; Hiroko Ariga; Satoru Takakusagi; Kenta Amemiya; Norimasa Yokoyama; Daisuke Yokoyama
    Photon Factory Activity Report 2011 PART B, 29巻, 出版日 2012年
    研究論文(学術雑誌), 英語
  • Alkali-Metal-Promoted Catalysis with Platinum / Titanium Dioxide for Formaldehyde Oxidation at Ambient Temperatures
    C. Zhang; F. Liu; Y. Zhai; H. Ariga; N. Yi; Y. Liu; K. Asakura; M. Flytzani-stephanopoulos; H. He
    Angewandte Chemie International Edition in English, 51巻, 掲載ページ 1-6, 出版日 2012年, 査読付
    研究論文(学術雑誌), 英語
  • Remarkable enhancement of Cu catalyst activity in hydrogenation of dimethyl oxalate to ethylene glycol using gold
    Ya-nan Wang; Xinping Duan; Jianwei Zheng; Haiqiang Lin; Youzhu Yuan; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    CATALYSIS SCIENCE & TECHNOLOGY, ROYAL SOC CHEMISTRY, 2巻, 8号, 掲載ページ 1637-1639, 出版日 2012年, The performance of an SBA-15-supported Cu catalyst for hydrogenation of dimethyl oxalate to ethylene glycol is markedly promoted with Au. A key genesis of the high activity of the catalyst is ascribed to the formation of Cu-Au alloy nanoparticles which stabilize the active species and retard their agglomeration during the hydrogenation process.
    研究論文(学術雑誌), 英語
  • Carbon Nanotube-Supported RuFe Bimetallic Nanoparticles as Efficient and Robust Catalysts for Aqueous-Phase Selective Hydrogenolysis of Glycerol to Glycols
    Bodong Li; Juan Wang; Youzhu Yuan; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    ACS CATALYSIS, AMER CHEMICAL SOC, 1巻, 11号, 掲載ページ 1521-1528, 出版日 2011年11月, 査読付, Carbon nanotube-supported RuFe bimetallic catalysts (RuFe/CNT) were prepared through a coimpregnation method for the selective hydrogenolysis of 20 wt % glycerol aqueous solution to produce glycols (1,2-propanediol and ethylene glycol). The Ru/CNT catalyst with smaller Ru nanoparticles (NPs) was significantly active for C-C bond cleavage, giving a considerable amount of CH(4) in the hydrogenolysis product. The RuFe/CNT catalyst with bimetallic NPs having an average size similar to Ru/CNT was more efficient for C-O bond cleavage, affording higher selectivity to glycols. Almost 100% glycerol conversion and over 75% selectivity to glycol could be obtained using the optimized RuFe/CNT catalyst under relatively mild conditions. The bimetallic RuFe/CNT catalyst was structurally robust and showed excellent reusability. Transmission electron microscopic images revealed that, when an appropriate amount of Fe entity was added, the RuFe bimetallic NPs were uniformly dispersed on the CNT surfaces and had an average size of similar to 3 nm. X-ray photoelectron spectroscopy indicated that a portion of the Fe species were interacted with Ru moieties, forming Ru-Fe alloys on the Ru domain, whereas other Fe species were in the forms of iron oxides, likely FeO and FeO(1+x) (0 < x < 0.5), mostly presenting on the periphery of RuFe bimetallic NPs. The occurrence of iron oxide species is crucial for the stability of RuFe bimetallic NPs during catalytic runs; but excess iron oxides block the surfaces of RuFe bimetallic NPs, resulting in a decrease in catalytic activity. Higher performance of the RuFe/CNT catalyst is attributed to the synergistic effects of the formation of Ru-Fe alloys and the interactions between the RuFe bimetallic NPs and iron oxides on CNT surfaces.
    研究論文(学術雑誌), 英語
  • Carbon Nanotube-Supported RuFe Bimetallic Nanoparticles as Efficient and Robust Catalysts for Aqueous-Phase Selective Hydrogenolysis of Glycerol to Glycols
    Bodong Li; Juan Wang; Youzhu Yuan; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    ACS CATALYSIS, AMER CHEMICAL SOC, 1巻, 11号, 掲載ページ 1521-1528, 出版日 2011年11月, Carbon nanotube-supported RuFe bimetallic catalysts (RuFe/CNT) were prepared through a coimpregnation method for the selective hydrogenolysis of 20 wt % glycerol aqueous solution to produce glycols (1,2-propanediol and ethylene glycol). The Ru/CNT catalyst with smaller Ru nanoparticles (NPs) was significantly active for C-C bond cleavage, giving a considerable amount of CH(4) in the hydrogenolysis product. The RuFe/CNT catalyst with bimetallic NPs having an average size similar to Ru/CNT was more efficient for C-O bond cleavage, affording higher selectivity to glycols. Almost 100% glycerol conversion and over 75% selectivity to glycol could be obtained using the optimized RuFe/CNT catalyst under relatively mild conditions. The bimetallic RuFe/CNT catalyst was structurally robust and showed excellent reusability. Transmission electron microscopic images revealed that, when an appropriate amount of Fe entity was added, the RuFe bimetallic NPs were uniformly dispersed on the CNT surfaces and had an average size of similar to 3 nm. X-ray photoelectron spectroscopy indicated that a portion of the Fe species were interacted with Ru moieties, forming Ru-Fe alloys on the Ru domain, whereas other Fe species were in the forms of iron oxides, likely FeO and FeO(1+x) (0 < x < 0.5), mostly presenting on the periphery of RuFe bimetallic NPs. The occurrence of iron oxide species is crucial for the stability of RuFe bimetallic NPs during catalytic runs; but excess iron oxides block the surfaces of RuFe bimetallic NPs, resulting in a decrease in catalytic activity. Higher performance of the RuFe/CNT catalyst is attributed to the synergistic effects of the formation of Ru-Fe alloys and the interactions between the RuFe bimetallic NPs and iron oxides on CNT surfaces.
    研究論文(学術雑誌), 英語
  • Interaction of Water with FeO(111)/Pt(111): Environmental Effects and Influence of Oxygen
    Franziska Ringleb; Yuichi Fujimori; Hui-Feng Wang; Hiroko Ariga; Esther Carrasco; Martin Sterrer; Hans-Joachim Freund; Livia Giordano; Gianfranco Pacchioni; Jacek Goniakowski
    JOURNAL OF PHYSICAL CHEMISTRY C, AMER CHEMICAL SOC, 115巻, 39号, 掲載ページ 19328-19335, 出版日 2011年10月, 査読付, The structural and chemical properties of a monolayer FeO(111)/Pt(111) exposed to air, liquid water, and controlled atmospheres of water vapor and water vapor/oxygen mixtures have been studied by a combination of infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning tunneling microscopy experiments together with density functional calculations using ab initio thermodynamics. The FeO(111)/Pt(111) film is inert toward pure water vapor up to mbar pressure. Coadsorption of oxygen and water, however, transforms the film into a hydroxyl terminated trilayer with a (Pt-)O-Fe-OH structural motif. The trilayer film forms spontaneously upon contact of FeO(111)/Pt(111) with air and preserves long-range order even in liquid water. The calculated phase diagram in the relevant range of oxygen and water chemical potentials is in agreement with the experimental results and shows that the oxygen chemical potential is the main driving force for the formation of the trilayer film. Results for Au nucleation on and CO oxidation over the FeO(OH) film are presented and compared to previous studies on nonhydroxylated films.
    研究論文(学術雑誌), 英語
  • Dynamical LEED analysis of Ni2P (0001)-1 x 1: Evidence for P-covered surface structure
    Alvin B. Hernandez; Hiroko Ariga; Satoru Takakusagi; Kumiko Kinoshita; Shushi Suzuki; Shigeki Otani; S. Ted Oyama; Kiyotaka Asakura
    CHEMICAL PHYSICS LETTERS, ELSEVIER SCIENCE BV, 513巻, 1-3号, 掲載ページ 48-52, 出版日 2011年09月, 査読付, Nickel phosphide (Ni2P) is an emerging catalyst for hydrodesulfurization and other important environment- and energy-related catalytic reactions. To understand its high performance, the surface structure of a Ni2P (0 0 0 1) single crystal surface was investigated using dynamical LEED analysis. The obtained surface structure for Ni2P (0 0 0 1)-1 x 1 is a P-covered Ni3P2 structure (Ni3P_P structure) as opposed to the expected bulk terminated surface structures. This Letter discusses the driving force for the formation of the Ni3P_P surface, which involves the minimization of dangling bonds. (C) 2011 Elsevier B. V. All rights reserved.
    研究論文(学術雑誌), 英語
  • PTRF-XAFS Study of Atomically Dispersed Cu Species on a TiO2(110) Surface Premodified with Functional Organic Molecules
    Satoru Takakusagi; Hirotaka Nojima; Kotaro Miyazaki; Takahiro Wada; Hiroko Ariga; Wang-Jae Chun; Masaharu Nomura; Yasuhiro Iwasawa; Kiyotaka Asakura
    Photon Factory Activity Report 2010 PART B, 28巻, 出版日 2011年
    研究論文(学術雑誌), 英語
  • STM studies on the reconstruction of the Ni2P (10(1)over-bar0) surface
    Donghui Guo; Yuta Nakagawa; Hiroko Ariga; Shushi Suzuki; Kumiko Kinoshita; Takeshi Miyamoto; Satoru Takakusagi; Kiyotaka Asakura; Shigeki Otani; S. Ted Oyama
    SURFACE SCIENCE, ELSEVIER SCIENCE BV, 604巻, 17-18号, 掲載ページ 1347-1352, 出版日 2010年08月, 査読付, The surface structure of Ni2P (10 (1) over bar0), a model for highly active hydrodesulfurization catalysts, was studied using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) in order to understand the reconstruction of the surface layers. Annealing at 573 K revealed a (1 x 1) LEED pattern which changed to a c(2 x 4) arrangement by further heating to 723 K. Atomic scale STM images were obtained for both the (1 x 1) and c(2 x 4) structures. Bright spots observed in the STM images were interpreted to be due to surface phosphorus atoms and this was supported by a density functional theory (INT) simulation. Several possible models for the c(2 x 4) reconstructed structures were proposed including a P-dimer defect model, a missing-row model and a missing-row + added-row model. The last model gave the best explanation for the c(2 x 4) structure. The mechanism for the c(2 x 4) reconstruction on the Ni2P (10 (1) over bar0) surface is discussed. (C) 2010 Elsevier B.V. All rights reserved.
    研究論文(学術雑誌), 英語
  • Hydrodesulfurizaiton Reaction Mechanism of Ni2P/MCM-41 by Operando Analysis
    Takahiro Wada; Kyoko K. Bando; Takeshi Miyamoto; S. Ted Oyama; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Aasakura
    Photon Factory Activity Report 2009 PART B, 27巻, 出版日 2010年
    研究論文(学術雑誌), 英語
  • PTRF-XAFS analysis of structure of Au11 cluster on TiO2(110) Surface
    Satoru Takakusagi; Kotaro Miyazaki; Hirotaka Nojima; Takahiro Wada; Hiroko Ariga; Wang-Jae Chun; Masaharu Nomura; Kiyotaka Aasakura; Yasuhiro Iwasawa
    Photon Factory Activity Report 2009 PART B, 27巻, 出版日 2010年
    研究論文(学術雑誌), 英語
  • Surface-Mediated Visible-Light Photo-oxidation on Pure TiO2(001)
    Hiroko Ariga; Toshiaki Taniike; Harumo Morikawa; Mizuki Tada; Byoung Koun Min; Kazuya Watanabe; Yoshiyasu Matsumoto; Susumu Ikeda; Koichiro Saiki; Yasuhiro Iwasawa
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 131巻, 41号, 掲載ページ 14670-+, 出版日 2009年10月, 査読付, We used STM to observe visible tight photo-oxidation reactions of formic acid on the ordered lattice-work structure of a TiO2(001) surface for the first time. The nanostructured surface makes the band gap significantly smaller than 3.0 eV only at the surface layer, and the surface state of the crystal enables a visible light response.
    研究論文(学術雑誌), 英語
  • Lattice-work structure of a TiO2(001) surface studied by STM, core-level spectroscopies and DFT calculations
    H. Ariga; T. Taniike; H. Morikawa; R. Tero; H. Kondoh; Y. Iwasawa
    CHEMICAL PHYSICS LETTERS, ELSEVIER SCIENCE BV, 454巻, 4-6号, 掲載ページ 350-354, 出版日 2008年03月, 査読付, The lattice-work structure of a rutile TiO2(001) surface, which is faceted to {114} plane, was studied by combining scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption. ne structure (NEXAFS) and density functional theory (DFT) calculations. Synchrotron XPS and NEXAFS spectra taken for the faceted surface indicated that this surface possesses a stoichiometric composition. We propose a new stoichiometric structure model on the basis of XPS, NEXAFS, and atomically-resolved STM observations. DFT calculations revealed that the present stoichiometric model is energetically more favorable compared to the previously proposed models. (c) 2008 Elsevier B.V. All rights reserved.
    研究論文(学術雑誌), 英語
  • STM study on photoreactions of adsorbed methanol and formic acid on a rutile TiO2(001) surface.
    H Ariga; R Tero; Y Namai; Y Iwasawa
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 227巻, 掲載ページ U1456-U1456, 出版日 2004年03月, 査読付
    英語
  • Photo-oxidation of methanol and formic acid on rutile TiO2(001) studied by STM
    H. Ariga; R. Tero; Y. Namai; Y. Iwasawa
    Microscopy and Microanalysis, 10巻, 2号, 掲載ページ 482-483, 出版日 2004年
    研究論文(国際会議プロシーディングス), 英語

MISC

  • アルカンとベンゼンの 直接結合反応のための 金属ナノ粒子 - ゼオライト複合触媒 酸点と Pd 粒子の近接による反応の高効率化を実現
    本倉健; 美崎慧; 三輪寛子; 伊藤孝
    出版日 2023年11月, 月刊JETI, 招待
  • μSRによるペプチド結合へのプロトネーションとプロトンダイナミクスの解析
    菅原洋子; 菅原洋子; PANT A.D.; 杉山純; 幸田章宏; 髭本亘; 下村浩一郎; 山口宏; 楠木正巳; 山村滋典; 三輪寛子; 鳥養映子; 永嶺謙忠; 神谷健秀
    出版日 2022年, 量子ビームサイエンスフェスタ(Web), 2021巻, 202202279902325125
  • 水素社会を目指した触媒と量子ビーム
    朝倉清高; 三輪寛子
    出版日 2022年, 量子ビームサイエンスフェスタ(Web), 2021巻, 202202280103346667
  • アークプラズム法でHOPG上に作成したPtAuナノ粒子の異常なAu-Au結合短縮について
    朝倉清高; HU Bing; 轟直人; 和田山智正; 東晃太朗; 宇留賀朋哉; 宇留賀朋哉; 岩澤康裕; 三輪(有賀)寛子; 高草木達
    出版日 2022年, 触媒討論会講演予稿集(CD-ROM), 129th巻, 2187-5928, 202202288976608672
  • 固体高分子形燃料電池カソードPt/C触媒粒子表面の吸着酸素種/硫黄種のin situ硬X線発光分光計測
    宇留賀朋哉; 宇留賀朋哉; 三輪寛子; 吉田健文; 金子拓真; 佐々木岳彦; 東晃太朗; 坂田智裕; 関澤央輝; 関澤央輝; 松井公佑; 朝倉清高; 唯美津木; 岩澤康裕
    出版日 2022年, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd巻, 2436-7613, 202302265876407716
  • TRHEPDで観測された非対称TiO2(110)(1x2)のDFTによる表面電子状態
    岩崎正弥; 三輪(有賀)寛子; 朝倉清高
    出版日 2021年, 日本表面真空学会東北・北海道支部学術講演会講演予稿集, 2020 (CD-ROM)巻, 202102268730884629
  • Thorough Search法による複雑な分子およびナノ材料におけるEXAFS 解析
    城戸大貴; 上村洋平; 脇坂祐輝; 三輪(有賀)寛子; 高草木達; 朝倉清高
    出版日 2021年, 日本表面真空学会学術講演会要旨集(Web), 2021巻, 2434-8589, 202202216109870597
  • TiO2(110)(1x2)の非対称化機構について
    岩崎正弥; 三輪寛子; 朝倉清高
    出版日 2021年, 触媒討論会討論会A予稿集(CD-ROM), 128th巻, 2758-3503, 202202222669436222
  • 高温反応条件下でのXAFSー反応解析の可能性
    KASHABOINA Upendar; 鮑徳玲; 城戸大貴; 三輪(有賀)寛子; 高草木達; 脇坂祐輝; 西川祐太; 井波雄太; 栗山史也; ARNOLDUSLAMBERTUS Dipu; 荻原仁志; 井口翔之; 山中一郎; 和田敬広; 朝倉清高
    出版日 2020年, 触媒討論会討論会A予稿集(CD-ROM), 126th巻, 2758-3503, 202102222954107414
  • μSR法を用いたrutile型TiO2の欠陥構造解析
    三輪寛子; 下村浩一郎; DATT Pant Amba; 鳥養映子; 永嶺兼忠; 朝倉清高
    出版日 2020年, 触媒討論会討論会A予稿集(CD-ROM), 126th巻, 2758-3503, 202102234878841744
  • Pt/TiO2(110)表面上メタノール分解反応における吸着種の動的挙動と反応特性の解明
    高草木達; 劉燦; 三輪寛子; 小倉正平; 福谷克之; 朝倉清高
    出版日 2020年, 触媒討論会討論会A予稿集(CD-ROM), 126th巻, 2758-3503, 202102236006847252
  • TiO2(110)-(1×2)再構成表面における非対称Ti2O3構造と表面安定化機構
    陶山なぎさ; 三輪寛子; 朝倉清高
    出版日 2019年, 触媒討論会討論会A予稿集(CD-ROM), 124th巻, 2758-3503, 202002219555353571
  • 表面制限還元置換法(SLRR)によるAu(111)表面のPtの化学種の構造
    朝倉清高; YUAN Qiuyi; 脇坂祐輝; 上村洋平; 和田敬広; 三輪(有賀)寛子; 高草木達
    出版日 2019年, 触媒討論会討論会A予稿集(CD-ROM), 124th巻, 2758-3503, 202002275866958082
  • Multiatom Resonance X-ray(MARX)Raman Spectroscopyと界面分子反応
    NATEE Sirisit; 城戸大貴; 脇坂祐輝; 三輪(有賀)寛子; 高草木達; 朝倉清高; 坂田智裕; 関澤央輝; 宇留賀朋哉; 岩澤康裕
    出版日 2018年, 触媒討論会討論会A予稿集, 122nd巻, 1343-9936, 201802230311904561
  • μSRの生命科学への展開へ向けて-タンパク質におけるミュオン停止位置の解析-
    菅原洋子; 藤田貴久; 柳原功; 山村滋典; PANT A. D.; 幸田章宏; 下村浩一郎; 髭本亘; 髭本亘; 石田勝彦; 楠木正巳; 三輪(有賀)寛子; PRATT F. L.; 藤牧拓郎; 白木一郎; 鳥養映子; 鳥養映子; 永嶺謙忠
    出版日 2018年, 量子ビームサイエンスフェスタ(Web), 2017巻, 202202225425362500
  • TiO2担持Re触媒を用いたカルボン酸の選択水素化反応
    鳥屋尾隆; 鳥屋尾隆; SIDDIKI S. M. A. H.; 森田能次; 蒲池高志; 蒲池高志; 三輪寛子; 朝倉清高; 吉澤一成; 吉澤一成; 清水研一; 清水研一
    出版日 2018年, 触媒討論会講演予稿集, 121st巻, 2187-5928, 201802219183929113
  • 全反射高速陽電子回折(TRHEPD)によるRutle‐TiO2(110)‐(1×2)表面構造の決定
    望月出海; 有賀寛子; 深谷有喜; 和田健; 朝倉清高; 一宮彪彦; 兵頭俊夫
    ルチル型TiO2結晶の(110)表面は、通常(1×1)構造が形成されるが、超高真空下1100K程度で焼鈍すると(1×2)構造が現れる。この原子配置については、X線や低速電子線回折実験、理論計算等の報告があるが未決定である。本研究は反射高速陽電子回折法を用いて、(1×2)構造を決定したので、それについて述べる。, 公益社団法人 日本表面科学会, 出版日 2015年12月01日, 表面科学学術講演会講演要旨集, 35th巻, 掲載ページ 217-426, 日本語, 201602206670437048, 130005489475
  • Investigation of the Cleanliness of Transferred Graphene: The First Step toward Its Application as a Window Material for Electron Microscopy and Spectroscopy
    Tao Ma; Kotaro Miyazaki; Hiroko Ariga; Satoru Takakusagi; Kiyotaka Asakura
    The cleanliness of transferred graphene is of significant importance for its application as the window material in environmental cells used for electron microscopy and spectroscopy. We investigated the dependence of the cleanliness of graphene on transfer routes, including FeCl3 etching, (NH4)(2)S2O8 etching, electrochemical delamination, and O(2-)bubbling, by means of transmission electron microscopy and X-ray photoelectron spectroscopy. It was found that electrochemical delamination provided the cleanest graphene with only a small amount of poly(methyl methacrylate) (PMMA) residue existing on the surface., CHEMICAL SOC JAPAN, 出版日 2015年08月, BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 88巻, 8号, 掲載ページ 1029-1035, 英語, 0009-2673, 1348-0634, 84940197141, WOS:000359513200003
  • μSR法によるTiO2の酸素欠陥観測
    有賀寛子; 下村浩一郎; PANT A.D; 鳥養映子; 永嶺兼忠; 朝倉清高
    出版日 2015年03月09日, 日本表面科学会東北・北海道支部講演会講演予稿集, 2014巻, 掲載ページ 16, 日本語, 201502255463863765
  • マルチプローブ研究が拓く構造研究の新時代 3.材料科学分野におけるマルチプローブ研究 Rutile型TiO2のナノ構造と物性 ポスト結晶構造解析
    有賀寛子; 朝倉清高
    出版日 2015年02月28日, 日本結晶学会誌, 57巻, 1号, 掲載ページ 41-46, 日本語, 0369-4585, 201502205838158684
  • メルカプト安息香酸修飾TiO2(110)によるNi単原子種の安定化と偏光全反射蛍光XAFS法による構造解析
    國本明駿; 高草木達; 有賀寛子; 上原広充; 大場惟史; 朝倉清高
    金属と強く相互作用するメルカプト基を有するメルカプト安息香酸でTiO2(110)表面を修飾し、その後AuまたはCuを蒸着することで、TiO2(110)表面上でのAu、Cuの単原子分散が可能である。本研究では、金属として新たにNiの単原子分散を試みた。Ni蒸着後の構造を偏光全反射蛍光XAFS法により評価し、単原子分散していることを見出した。また、単原子分散したNiの構造モデルについても考察した。, 公益社団法人 日本表面科学会, 出版日 2014年11月06日, 表面科学学術講演会講演要旨集, 34th巻, 掲載ページ 86-171, 日本語, 201402254547280672, 130005481168
  • 全反射高速陽電子回折によるTiO2(110)(1X2)表面構造解析
    朝倉清高; 有賀寛子; 望月出水; 和田健; 兵頭俊夫; 深谷有喜
    出版日 2014年09月18日, 触媒討論会討論会A予稿集, 114th巻, 掲載ページ 358, 日本語, 1343-9936, 201402286653187680
  • 酸素プラズマ照射による酸化物単結晶上に担持した有機保護金クラスターからのナノ粒子形成
    高草木達; 木工淳; IMRAN BIN ABDUL; R. M. Nabil; 上原広充; 有賀寛子; 朝倉清高
    出版日 2014年03月12日, 日本化学会講演予稿集, 94th巻, 3号, 掲載ページ 760, 日本語, 0285-7626, 201402283516834726
  • 酸化物担持有機保護金クラスターへの酸素プラズマ照射によるナノ粒子形成と粒径制御
    高草木達; 木工淳; MOHAMAD NABIL Imran; bin A. R; 上原広充; 有賀寛子; 朝倉清高
    出版日 2014年03月10日, 触媒討論会講演予稿集, 113th巻, 掲載ページ 255, 日本語, 2187-5928, 201402272547678135
  • Structures and propeties of Ni2P single crystal surface: A surface science approach to a new class of hydrodesulfurization catalyst
    Kiyotaka Asakura; Hiroko Ariga; Satoru Takakusagi; S. Ted Oyama
    AMER CHEMICAL SOC, 出版日 2014年03月, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 247巻, 英語, 研究発表ペーパー・要旨(国際会議), 0065-7727, WOS:000348457600126
  • 物構研におけるマルチプローブ利用研究のすすめ~放射光,低速陽電子,中性子,ミュオンを使って新しい世界を見てみよう~3 低速陽電子実験装置を利用して 反射高速陽電子回折(RHEPD)によるTiO2(110)(1×2)表面の構造解析
    朝倉清高; 有賀寛子; 望月出海; 深谷有喜; 和田健; 兵頭俊夫
    出版日 2014年02月, Photon Fact News, 31巻, 4号, 掲載ページ 38-41, 日本語, 0916-0604, 201502299902567687
  • 全反射高速陽電子回折によるTiO2(110)(1×2)再構成表面精密構造解析
    有賀寛子; 朝倉清高; 深谷有喜; 望月出海; 和田健; 兵頭俊夫
    出版日 2014年, 物構研サイエンスフェスタ要旨集, 2013巻, 掲載ページ 25, 日本語, 201402211457206588
  • 担持貴金属ナノ粒子のXAFSによる局所構造
    大場惟史; 上原広充; 有賀寛子; 高草木達; 牧田勇一; 大嶋優輔; 久保仁志; 中村紀章; 朝倉清高
    出版日 2014年, 物構研サイエンスフェスタ要旨集, 2013巻, 掲載ページ 53, 日本語, 201402239251657852
  • TiO2表面構造と触媒機能
    有賀寛子; 望月出海; 深谷有喜; 和田健; 兵頭俊夫; 朝倉清高
    出版日 2014年, 物構研サイエンスフェスタ要旨集, 2013巻, 掲載ページ 3, 日本語, 201402292603966786
  • Density Function Theoretical Investigation on the Ni3PP Structure and the Hydrogen Adsorption Property of the Ni2P(0001) Surface
    Hiroko Ariga; Mayumi Kawashima; Satoru Takakusagi; Kiyotaka Asakura
    The electronic and structural properties of a phosphorus-terminated structure of Ni2P(0001) surface (Ni3PP) are investigated by density functional theory (DFT) calculations. Phosphorus adsorption largely stabilizes the Ni2P(0001) surface by creating Ni-P bonds on the Ni trimer. Atomic hydrogen can adsorb on the topmost P site although its adsorption energy is much lower than its adsorption energy on the Ni trimer site of the Ni3P2 surface. Our results suggest that the Ni trimer is the key factor for high catalytic activity., CHEMICAL SOC JAPAN, 出版日 2013年12月, CHEMISTRY LETTERS, 42巻, 12号, 掲載ページ 1481-1483, 英語, 0366-7022, 1348-0715, 130004867825, WOS:000327917100009
  • 水素化触媒Ni2P(0001)表面上の水素吸着
    有賀寛子; 宮本剛史; ALVIN Hernandez; 高草木達; 大谷茂樹; 大山Ted; 朝倉清高
    出版日 2013年11月26日, 表面科学学術講演会講演要旨集, 33rd巻, 掲載ページ 125, 日本語, 201402203389183806
  • 光電子顕微鏡を用いた大気圧条件下での金薄膜の観察
    北山冬馬; 朝倉清高; 高草木達; 有賀寛子; 上原広充; 宮崎晃太朗; 津野勝重; 工藤雅嗣; 平岩端
    出版日 2013年11月26日, 表面科学学術講演会講演要旨集, 33rd巻, 掲載ページ 180, 日本語, 201402216301229873
  • 高輝度反射高速陽電子回折によるTiO2(110)‐(1×2)表面構造の解析
    望月出海; 有賀寛子; 深谷有喜; 和田健; 兵頭俊夫; 朝倉清高; 前川雅樹; 河裾厚男
    出版日 2013年11月26日, 表面科学学術講演会講演要旨集, 33rd巻, 掲載ページ 108, 日本語, 201402252683891305
  • Ni2P(1010)単結晶表面の酸化過程のSTM観察
    鴻野健太郎; 有賀寛子; 高草木達; 上原広充; 大谷茂樹; OYAMA S.Ted; 朝倉清高
    出版日 2013年11月26日, 表面科学学術講演会講演要旨集, 33rd巻, 掲載ページ 40, 日本語, 201402284042130877
  • 酸素プラズマ照射による酸化物上金ナノ粒子のサイズ及び化学状態変化の観察
    木工淳; 高草木達; ラフマン モハマド・ナビル; イムラン・ビン・アブドル; 上原広充; 有賀寛子; 朝倉清高
    出版日 2013年11月26日, 表面科学学術講演会講演要旨集, 33rd巻, 掲載ページ 31, 日本語, 201402287223375269
  • 電気化学的手法を用いたPt/TiO2(110)モデル触媒表面の調製
    高草木達; 小川貴史; 上原広充; 有賀寛子; 朝倉清高
    出版日 2013年09月11日, 触媒討論会討論会A予稿集, 112th巻, 掲載ページ 413, 日本語, 1343-9936, 201302208825160196
  • 27aJB-8 光電子回折分光法による脱硫触媒Ni_2P及び関連合金表面の原子構造・電子状態解析と触媒活性の相関(表面界面構造,領域9(表面・界面,結晶成長))
    松井 公佑; 松井 文彦; 前島 尚行; 有賀 寛子; 朝倉 清高; 松下 智裕; 大門 寛
    一般社団法人日本物理学会, 出版日 2013年08月26日, 日本物理学会講演概要集, 68巻, 2号, 掲載ページ 806-806, 日本語, 1342-8349, 110009756255, AA11439205
  • 27aJB-9 高輝度反射高速陽電子回折によるTiO_2(110)表面の構造解析(表面界面構造,領域9(表面・界面,結晶成長))
    望月 出海; 有賀 寛子; 深谷 有喜; 和田 健; 兵頭 俊夫; 朝倉 清高; 前川 雅樹; 河裾 厚男
    一般社団法人日本物理学会, 出版日 2013年08月26日, 日本物理学会講演概要集, 68巻, 2号, 掲載ページ 806-806, 日本語, 1342-8349, 110009756256, AA11439205
  • 光電子回折分光法による脱硫触媒Ni2P及び関連合金表面の原子構造・電子状態解析と触媒活性の相関
    松井公佑; 松井文彦; 前島尚行; 有賀寛子; 朝倉清高; 松下智裕; 大門寛
    一般社団法人日本物理学会, 出版日 2013年08月26日, 日本物理学会講演概要集, 68巻, 2号, 掲載ページ 806-806, 日本語, 1342-8349, 201302281334572980, 110009756255, AA11439205
  • 高輝度反射高速陽電子回折によるTiO2(110)表面の構造解析
    望月出海; 有賀寛子; 深谷有喜; 和田健; 兵頭俊夫; 朝倉清高; 前川雅樹; 河裾厚男
    一般社団法人日本物理学会, 出版日 2013年08月26日, 日本物理学会講演概要集, 68巻, 2号, 掲載ページ 806-806, 日本語, 1342-8349, 201302282115494872, 110009756256, AA11439205
  • 高輝度反射高速陽電子回折によるTiO2(110)表面の構造解析
    望月出海; 有賀寛子; 深谷有喜; 和田健; 兵頭俊夫; 朝倉清高; 前川雅樹; 河裾厚男
    出版日 2013年06月20日, アイソトープ・放射線研究発表会要旨集, 50th巻, 掲載ページ 47, 日本語, 201302231251598564
  • Anisotropic growth of a nickel trimer formed on a highly-stepped TiO2(110) surface
    Hiromitsu Uehara; Muhammad Haneef Bin Hanaffi; Yuichiro Koike; Keisuke Fujikawa; Shushi Suzuki; Hiroko Ariga; Satoru Takakusagi; Wang-Jae Chun; Yasuhiro Iwasawa; Kiyotaka Asakura
    The structures of Ni clusters formed on a highly-stepped TiO2(110) surface were studied by polarization-dependent total reflection fluorescence X-ray absorption fine structure analysis. When 0.8 monolayers of Ni were deposited, three-dimensional Ni clusters with 1-2 nm diameters and heights less than 1 nm were formed. Conversely, when 0.07 monolayers of Ni were deposited, an anisotropic Ni trimer with a Ni-Ni distance of 0.260 nm was created at the [001] step. We revealed that the surface modification to enhance the metal-anion interaction can control the deposited metal structure. (C) 2013 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 出版日 2013年05月, CHEMICAL PHYSICS LETTERS, 570巻, 掲載ページ 64-69, 英語, 0009-2614, 1873-4448, 120005307929, WOS:000319102100014
  • 金属結合能を有する機能性分子を共存させた酸化物表面上での単原子金属種の調製
    高草木達; 野島大孝; 宮崎晃太郎; 有賀寛子; 上原広充; 田旺帝; 岩澤康裕; 朝倉清高
    出版日 2013年03月11日, 触媒討論会講演予稿集, 111th巻, 掲載ページ 228, 日本語, 2187-5928, 201302299427028836
  • STMによるNi2P(1010)単結晶表面の表面構造と反応性に関する研究
    鴻野健太郎; 有賀寛子; 高草木達; 大谷茂樹; OYAMA S. Ted; 朝倉清高
    出版日 2013年03月08日, 日本化学会講演予稿集, 93rd巻, 2号, 掲載ページ 460, 日本語, 0285-7626, 201302201089211506
  • メルカプト基を有する機能性分子で修飾した酸化物表面でのAu単原子種の調製
    高草木達; 野島大孝; 宮崎晃太郎; 有賀寛子; 上原広充; CHUN Wang‐Jae; 岩澤康裕; 朝倉清高
    出版日 2013年03月08日, 日本化学会講演予稿集, 93rd巻, 3号, 掲載ページ 757, 日本語, 0285-7626, 201302214057886085
  • 水素化脱硫触媒Ni2P(0001)表面上での水素挙動
    有賀寛子; 宮本剛史; HERNANDEZ Alvin; 木下久美子; 高草木達; 大谷茂樹; 大山Ted; 朝倉清高
    出版日 2013年03月08日, 日本化学会講演予稿集, 93rd巻, 2号, 掲載ページ 504, 日本語, 0285-7626, 201302238626454357
  • Silver-modulated SiO2-supported copper catalysts for selective hydrogenation of dimethyl oxalate to ethylene glycol
    Ying Huang; Hiroko Ariga; Xinlei Zheng; Xinping Duan; Satoru Takakusagi; Kiyotaka Asakura; Youzhu Yuan
    We present the application of a one-step urea-assisted gelation method to prepare a SiO2-supported bimetallic catalyst composed of copper (Cu) and silver (Ag). Results show the remarkably enhanced performance of the catalyst for selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Coupled with a series of characterization and kinetic studies, the improved activity is attributed to the formation of Cu nanoparticles containing Ag nanoclusters on the SiO2 surface. The coherent interactions between the Cu and Ag species help create the active Cu+/Cu 0 species in a suitable proportion and prevent the transmigration of bimetallic nanoparticles during the hydrogenation process. The optimized CuAg/SiO2 catalyst with an Ag/Cu atomic ratio of 0.05 has a balanced Cu+/Cu0 ratio and highly dispersed bimetal particles, which account for its high turnover frequency, EG selectivity of 97.0%, and excellent catalytic stability during the hydrogenation of DMO to EG for longer than 150 h. © 2013 Elsevier Inc. All rights reserved., Academic Press Inc. Elsevier Science, 出版日 2013年, Journal of Catalysis, 307巻, 掲載ページ 74-83, 英語, 0021-9517, 120005372276, 84881126493
  • Preparation and structure of a single Au atom on the TiO2(110) surface: control of the Au-metal oxide surface interaction
    Kiyotaka Asakura; Satoru Takakusagi; Hiroko Ariga; Wang-Jae Chun; Shushi Suzuki; Yuichiro Koike; Hiromitsu Uehara; Kotaro Miyazaki; Yasuhiro Iwasawa
    Three-dimensional Au structures on bare and organic-compound-modified TiO2(110) surfaces were interrogated by Au L-3-edge polarization dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) spectroscopy. On the bare TiO2(110) surface, icosahedral Au-55 nanoclusters were the main product found. When the surfaces were modified with ortho or meso mercaptobenzoic acid (o-MBA or m-MBA), Au was atomically dispersed. Sulfur atoms in the o- and m-MBA formed strong covalent bonds with Au to produce stable Au-MBA (o-and m-forms) surface complexes. On the other hand, only oxygen atoms on the surface did not make a strong enough interaction to stabilize the Au species. We discuss how the Au species formed on the modified TiO2(110) surface and the possibility to control the Au structure by the surface modification method., ROYAL SOC CHEMISTRY, 出版日 2013年, FARADAY DISCUSSIONS, 162巻, 掲載ページ 165-177, 英語, 1359-6640, 120005356862, WOS:000321591000009
  • 規整不均一α‐Sb2O4/VSbO4触媒の調製とその反応活性
    朝倉清高; 原口惟; 和田敬広; 有賀寛子; 高草木達
    出版日 2012年09月14日, 触媒討論会討論会A予稿集, 110th巻, 掲載ページ 355, 日本語, 1343-9936, 201202236021919870
  • プラズマ処理による酸化物上金粒子の高分散化
    高草木達; NABIL Imran bin; Abdul R. M; 木工淳; 上原広充; 有賀寛子; 朝倉清高
    出版日 2012年09月14日, 触媒討論会討論会A予稿集, 110th巻, 掲載ページ 340, 日本語, 1343-9936, 201202281994624900
  • ドイツとスイス研究記
    有賀 寛子
    出版日 2012年09月10日, 表面科学 : hyomen kagaku = Journal of the Surface Science Society of Japan, 33巻, 9号, 掲載ページ 530-531, 日本語, 0388-5321, 10031068601, AN00334149
  • 電子線リソグラフィを用いた規整不均一α-Sb_2O_4/VSbO_4触媒の調製とその反応活性
    原口 惟; 和田 敬広; 大南 祐介; 松平 宣明; 有賀 寛子; 高草木 達; 朝倉 清高
    Well-defined inhomogeneous α-Sb2O4/VSbO4 catalysts were prepared using an electron lithography method to investigate the effects of µm order structures on an atomic scale catalytic reaction. X-ray photoelectron spectroscopy (XPS) and laser microscopy revealed that µm order structures were successfully developed on a Si substrate where an α-Sb2O4 micro line with a controlled width was deposited on VSbO4. We carried out a propene partial oxidation reaction on this surface and found that the acrolein formation rate was significantly influenced by the width and interval of the α-Sb2O4 µm line. The results of this study indicate the possibility of controlling the surface reaction by the inhomogeneity of the surface structure in the µm order., The Surface Science Society of Japan, 出版日 2012年08月10日, 表面科学 : hyomen kagaku = Journal of the Surface Science Society of Japan, 33巻, 8号, 掲載ページ 426-430, 日本語, 0388-5321, 10030984186, AN00334149
  • モデル脱硫触媒としてのNi_2P単結晶の表面構造と反応活性
    朝倉 清高; 有賀 寛子; 高草木 達; 宮本 剛志
    触媒学会, 出版日 2012年03月10日, 觸媒 = Catalyst, 54巻, 2号, 掲載ページ 138-140, 日本語, 0559-8958, 201202249107997534, 10030179449, AN00117719
  • 電析によるPt/TiO2(110)モデル触媒表面の調製
    高草木達; 小川貴史; 上原広充; 有賀寛子; 朝倉清高
    出版日 2012年03月09日, 日本化学会講演予稿集, 92nd巻, 2号, 掲載ページ 216, 日本語, 0285-7626, 201202241063180755
  • Surface science approach to catalyst preparation – Pd deposition onto thin Fe3 O4 (111) films from PdCl2 precursor
    Hui-Feng Wang; Hiroko Ariga; Rhys Dowler; Martin Sterrer; Hans-Joachim Freund
    In this work, we introduce a surface science approach to supported metal catalyst preparation utilizing thin, single-crystalline oxide films as substrates. The use of thin oxide films allows for combined morphological and chemical characterization of the sample at various steps of a typical catalyst preparation procedure. A Fe3O4-supported Pd model catalyst was prepared by impregnation of (FeO4)-O-3(1 1 1) films with acidic PdCl2 solution, and the transformation of the adsorbed precursor into supported Pd nanoparticles by stepwise heating in vacuum was followed with scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The results provide evidence for homogeneous nucleation of Pd particles out of a monolayer of adsorbed precursor and an enhancement of the particle-support interaction with increasing annealing temperature. Chlorine, which remains on the model catalyst surface after vacuum annealing, could be removed by oxidation/reduction. This treatment also leads to particle sintering with an increase in the average particle diameter from 2 nm to 4 nm after oxidation/reduction. (C) 2011 Elsevier Inc. All rights reserved., ACADEMIC PRESS INC ELSEVIER SCIENCE, 出版日 2012年02月, Journal of Catalysis, 286巻, 掲載ページ 1-5, 英語, 0021-9517, WOS:000300141300001
  • 電子線リソグラフィを用いた規整不均一α‐Sb2O4/VSbO4触媒の調製とその反応活性
    原口惟; 和田敬広; 大南祐介; 松平宣明; 有賀寛子; 高草木達; 朝倉清高
    Well-defined inhomogeneous α-Sb2O4/VSbO4 catalysts were prepared using an electron lithography method to investigate the effects of µm order structures on an atomic scale catalytic reaction. X-ray photoelectron spectroscopy (XPS) and laser microscopy revealed that µm order structures were successfully developed on a Si substrate where an α-Sb2O4 micro line with a controlled width was deposited on VSbO4. We carried out a propene partial oxidation reaction on this surface and found that the acrolein formation rate was significantly influenced by the width and interval of the α-Sb2O4 µm line. The results of this study indicate the possibility of controlling the surface reaction by the inhomogeneity of the surface structure in the µm order., The Surface Science Society of Japan, 出版日 2012年, 表面科学, 33巻, 8号, 掲載ページ 426-430 (J-STAGE)-430, 日本語, 0388-5321, 201302203742549332, 10030984186, AN00334149
  • 遷移金属リン化物表面の構造と安定化要因
    朝倉清高; 有賀寛子; 高草木達; 鈴木秀志; 大谷茂樹; 大山茂; ALVIN Henandez; 木下久美子
    出版日 2011年12月15日, 表面科学学術講演会講演要旨集, 31st巻, 掲載ページ 174, 日本語, 201202222540603430
  • 電気化学的手法によるPt/TiO2(110)モデル触媒表面の精密調整
    小川貴史; 高草木達; 上原広充; 有賀寛子; 朝倉清高
    出版日 2011年12月15日, 表面科学学術講演会講演要旨集, 31st巻, 掲載ページ 110, 日本語, 201202247187923878
  • 電子線リソグラフィを用いたα‐Sb2O4/VSbO4薄膜の触媒反応活性とその機構解明
    原口惟; 和田敬広; 有賀寛子; 高草木達; 朝倉清高
    出版日 2011年12月15日, 表面科学学術講演会講演要旨集, 31st巻, 掲載ページ 175, 日本語, 201202290215210524
  • 超高速透過型電子顕微鏡
    有賀 寛子
    出版日 2011年12月10日, 觸媒 = Catalyst, 53巻, 7号, 掲載ページ 444-444, 日本語, 0559-8958, 10030178922, AN00117719
  • Interaction of Water with FeO(111)/Pt(111): Environmental Effects and Influence of Oxygen
    Franziska Ringleb; Yuichi Fujimori; Hui-Feng Wang; Hiroko Ariga; Esther Carrasco; Martin Sterrer; Hans-Joachim Freund; Livia Giordano; Gianfranco Pacchioni; Jacek Goniakowski
    The structural and chemical properties of a monolayer FeO(111)/Pt(111) exposed to air, liquid water, and controlled atmospheres of water vapor and water vapor/oxygen mixtures have been studied by a combination of infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning tunneling microscopy experiments together with density functional calculations using ab initio thermodynamics. The FeO(111)/Pt(111) film is inert toward pure water vapor up to mbar pressure. Coadsorption of oxygen and water, however, transforms the film into a hydroxyl terminated trilayer with a (Pt-)O-Fe-OH structural motif. The trilayer film forms spontaneously upon contact of FeO(111)/Pt(111) with air and preserves long-range order even in liquid water. The calculated phase diagram in the relevant range of oxygen and water chemical potentials is in agreement with the experimental results and shows that the oxygen chemical potential is the main driving force for the formation of the trilayer film. Results for Au nucleation on and CO oxidation over the FeO(OH) film are presented and compared to previous studies on nonhydroxylated films., AMER CHEMICAL SOC, 出版日 2011年10月, JOURNAL OF PHYSICAL CHEMISTRY C, 115巻, 39号, 掲載ページ 19328-19335, 英語, 1932-7447, 80022119506, WOS:000295245500053
  • 水素化脱硫触媒Ni2Pの表面構造と反応性
    有賀寛子; フェルナンデス アルビン; 木下久美子; 高草木達; 大谷茂樹; 大山S.Ted; 朝倉清高
    出版日 2011年09月13日, 触媒討論会討論会A予稿集, 108th巻, 掲載ページ 312, 日本語, 1343-9936, 201102239753092229
  • 二次元光電子回折分光法による脱硫触媒Ni2P(10‐10)の局所原子構造・電子状態解析
    松井公佑; 松井文彦; 後藤謙太郎; 前島尚行; 松下智裕; 有賀寛子; 朝倉清高; 大門寛
    出版日 2011年09月13日, 触媒討論会討論会A予稿集, 108th巻, 掲載ページ 14, 日本語, 1343-9936, 201102249607620804
  • Dynamical LEED analysis of Ni2P (0001)-1 x 1: Evidence for P-covered surface structure
    Alvin B. Hernandez; Hiroko Ariga; Satoru Takakusagi; Kumiko Kinoshita; Shushi Suzuki; Shigeki Otani; S. Ted Oyama; Kiyotaka Asakura
    Nickel phosphide (Ni2P) is an emerging catalyst for hydrodesulfurization and other important environment- and energy-related catalytic reactions. To understand its high performance, the surface structure of a Ni2P (0 0 0 1) single crystal surface was investigated using dynamical LEED analysis. The obtained surface structure for Ni2P (0 0 0 1)-1 x 1 is a P-covered Ni3P2 structure (Ni3P_P structure) as opposed to the expected bulk terminated surface structures. This Letter discusses the driving force for the formation of the Ni3P_P surface, which involves the minimization of dangling bonds. (C) 2011 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE BV, 出版日 2011年09月, CHEMICAL PHYSICS LETTERS, 513巻, 1-3号, 掲載ページ 48-52, 英語, 0009-2614, 1873-4448, 120003311424, 80052260411, WOS:000294281900009
  • 円偏光二次元光電子回折・分光による脱硫触媒Ni2P(1010)の局所構造・電子状態解析
    松井公佑; 松井文彦; 後藤謙太郎; 前島尚行; 松下智裕; 有賀寛子; 朝倉清高; 大門寛
    一般社団法人日本物理学会, 出版日 2011年03月03日, 日本物理学会講演概要集, 66巻, 1号, 掲載ページ 927-927, 日本語, 1342-8349, 201102239283510290, 110008715607, AA11439205
  • 27pPSA-26 円偏光二次元光電子回折・分光による脱硫触媒Ni_2P(1010^^-)の局所構造・電子状態解析(27pPSA 領域9ポスターセッション,領域9(表面・界面,結晶成長))
    松井 公佑; 松井 文彦; 後藤 謙太郎; 前島 尚行; 松下 智裕; 有賀 寛子; 朝倉 清高; 大門 寛
    社団法人日本物理学会, 出版日 2011年03月03日, 日本物理学会講演概要集, 66巻, 1号, 掲載ページ 927-927, 日本語, 1342-8349, 110008715607, AA11439205
  • 円偏光二次元光電子回折による脱硫触媒Ni2P(10-10)の原子構造解析
    松井公佑; 松井文彦; 後藤謙太郎; 前島尚行; 松下智裕; 有賀寛子; 朝倉清高; 大門寛
    出版日 2011年01月07日, 日本放射光学会年会・放射光科学合同シンポジウム予稿集, 24th巻, 掲載ページ 94, 日本語, 201102230175260264
  • 機能性分子修飾による酸化物表面上Cu種の構造制御
    高草木達; 野島大孝; 宮崎晃太朗; 和田敬広; 有賀寛子; 田旺帝; 野村昌治; 朝倉清高
    出版日 2011年01月07日, 日本放射光学会年会・放射光科学合同シンポジウム予稿集, 24th巻, 掲載ページ 143, 日本語, 201102259657517490
  • 水素化脱硫反応中のNi2P触媒のXANES変化
    和田敬広; 阪東恭子; 宮本剛志; 有賀寛子; 高草木達; OYAMA S. Ted; 朝倉清高
    出版日 2011年, PFシンポジウム要旨集, 28th巻, 掲載ページ 28, 日本語, 201102229379941807
  • 機能性分子修飾による酸化物表面上Cu種の構造制御
    高草木達; 野島大孝; 宮崎晃太朗; 和田敬広; 有賀寛子; 田旺帝; 野村昌治; 朝倉清高
    出版日 2010年11月04日, 表面科学学術講演会講演要旨集, 30th巻, 掲載ページ 67, 日本語, 201102204525721307
  • 電子線リソグラフィを用いたα‐Sb2O4/VSbO4薄膜触媒の部分酸化反応の制御
    原口惟; 和田敬広; 有賀寛子; 高草木達; 朝倉清高
    出版日 2010年11月04日, 表面科学学術講演会講演要旨集, 30th巻, 掲載ページ 412, 日本語, 201102214221074297
  • 金属担体相互作用―偏光全反射蛍光XAFS法による研究例―
    朝倉清高; 高草木達; 有賀寛子; CHUN Wang Jae
    出版日 2010年09月15日, 触媒討論会討論会A予稿集, 106th巻, 掲載ページ 344, 日本語, 1343-9936, 201002239450897693
  • メルカプト安息香酸構造異性体によるTiO2(111)表面Cu化学種の構造制御
    野島大孝; 高草木達; 宮崎晃太朗; 和田敬広; 有賀寛子; CHUN Wang Jae; 野村昌治; 朝倉清高
    出版日 2010年09月15日, 触媒討論会討論会A予稿集, 106th巻, 掲載ページ 341, 日本語, 1343-9936, 201002230805417151
  • オペランド解析によるNi_2P脱硫触媒の活性点構造とその硫化効果
    和田 敬広; 阪東 恭子; 宮本 剛志; 有賀 寛子; 高草木 達; OYAMA S. Ted; 朝倉 清高
    触媒学会, 出版日 2010年09月04日, 觸媒 = Catalyst, 52巻, 6号, 掲載ページ 462-464, 日本語, 0559-8958, 201002255574429120, 10026583733, AN00117719
  • STM studies on the reconstruction of the Ni2P (101̅0) surface
    Donghui Guo; Yuta Nakagawa; Hiroko Ariga; Shushi Suzuki; Kumiko Kinoshita; Takeshi Miyamoto; Satoru Takakusagi; Kiyotaka Asakura; Shigeki Otani; S. Ted Oyama
    The surface structure of Ni2P (10 (1) over bar0), a model for highly active hydrodesulfurization catalysts, was studied using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) in order to understand the reconstruction of the surface layers. Annealing at 573 K revealed a (1 x 1) LEED pattern which changed to a c(2 x 4) arrangement by further heating to 723 K. Atomic scale STM images were obtained for both the (1 x 1) and c(2 x 4) structures. Bright spots observed in the STM images were interpreted to be due to surface phosphorus atoms and this was supported by a density functional theory (INT) simulation. Several possible models for the c(2 x 4) reconstructed structures were proposed including a P-dimer defect model, a missing-row model and a missing-row + added-row model. The last model gave the best explanation for the c(2 x 4) structure. The mechanism for the c(2 x 4) reconstruction on the Ni2P (10 (1) over bar0) surface is discussed. (C) 2010 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 出版日 2010年08月, Surface Science, 604巻, 17-18号, 掲載ページ 1347-1352, 英語, 0039-6028, 1879-2758, WOS:000280048900007
  • Surface-Mediated Visible-Light Photo-oxidation on Pure TiO2(001)
    Hiroko Ariga; Toshiaki Taniike; Harumo Morikawa; Mizuki Tada; Byoung Koun Min; Kazuya Watanabe; Yoshiyasu Matsumoto; Susumu Ikeda; Koichiro Saiki; Yasuhiro Iwasawa
    We used STM to observe visible tight photo-oxidation reactions of formic acid on the ordered lattice-work structure of a TiO2(001) surface for the first time. The nanostructured surface makes the band gap significantly smaller than 3.0 eV only at the surface layer, and the surface state of the crystal enables a visible light response., AMER CHEMICAL SOC, 出版日 2009年10月, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 131巻, 41号, 掲載ページ 14670-+, 英語, 0002-7863, 19780556, WOS:000271271800035
  • XPD及びNEXAFSによるMo(112)‐p(2x1)‐P表面構造とチオフェン分子の吸着構造の研究
    幸田竜; 近藤寛; 有賀寛子; 谷池俊明; 佐々木岳彦; LAURIN Mathias; 島田透; 岩澤康裕
    出版日 2008年03月12日, 日本化学会講演予稿集, 88th巻, 1号, 掲載ページ 47, 日本語, 0285-7626, 200902244749540468
  • Lattice-work structure of a TiO2(001) surface studied by STM, core-level spectroscopies and DFT calculations
    H. Ariga; T. Taniike; H. Morikawa; R. Tero; H. Kondoh; Y. Iwasawa
    The lattice-work structure of a rutile TiO2(001) surface, which is faceted to {114} plane, was studied by combining scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption. ne structure (NEXAFS) and density functional theory (DFT) calculations. Synchrotron XPS and NEXAFS spectra taken for the faceted surface indicated that this surface possesses a stoichiometric composition. We propose a new stoichiometric structure model on the basis of XPS, NEXAFS, and atomically-resolved STM observations. DFT calculations revealed that the present stoichiometric model is energetically more favorable compared to the previously proposed models. (c) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 出版日 2008年03月, CHEMICAL PHYSICS LETTERS, 454巻, 4-6号, 掲載ページ 350-354, 英語, 0009-2614, 80019457811, WOS:000254425200041
  • 走査トンネル顕微鏡とX線光電子回折によるMo(112)‐p(2×1)‐P構造とチオフェン分子の吸着及び分解挙動の解明
    幸田竜; 近藤寛; 有賀寛子; 谷池俊明; 佐々木岳彦; MATHIAS Laurin; 島田透; 岩澤康裕
    出版日 2007年11月01日, 表面科学講演大会講演要旨集, 27th巻, 掲載ページ 90, 日本語, 200902293592242523
  • 走査トンネル顕微鏡とX線光電子回折によるMo(112)-p(2x1)-P構造とチオフェン分子の吸着及び分解挙動の解明
    幸田 竜; 近藤 寛; 有賀 寛子; 谷池 俊明; 佐々木 岳彦; Laurin Mathias; 島田 透; 岩澤 康裕
    P修飾Mo(112)-p(2x1)がチオフェンの脱硫反応に高い活性をもつことを見出した。この表面構造においてはDFT計算によっていくつかのモデルが提案されているが未だ表面構造は不明である。特にチオフェン分解活性と表面構造との対応は触媒原理を明らかにする上で重要である。本研究では、走査トンネル顕微鏡とX線光電子回折を用いて構造を決定することに成功した。また、走査トンネル顕微鏡を用いてチオフェンの分解過程を観察した。, The Surface Science Society of Japan, 出版日 2007年, 表面科学講演大会講演要旨集, 27巻, 0号, 掲載ページ 90-90, 日本語, 130004673877
  • 二酸化チタン表面上での可視光誘起光反応とその反応機構
    有賀寛子; 谷池俊明; 唯美津木; 渡邊一也; 松本吉泰; 池田進; 斉木幸一朗; 岩澤康裕
    出版日 2006年11月21日, 固体・表面光化学討論会講演要旨集, 25th巻, 掲載ページ 50-51, 日本語, 200902213101542551
  • TiO2(001)表面階段状格子構造上で発現する可視光応答反応とその反応機構の解明
    有賀寛子; 谷池俊明; 守川春雲; MIN Byoung Koun; 唯美津木; 渡邊一也; 松本吉泰; 池田進; 斉木幸一朗; 岩澤康裕
    出版日 2006年09月26日, 触媒討論会討論会A予稿集, 98th巻, 掲載ページ 258, 日本語, 1343-9936, 200902264620442126
  • TiO2(001)表面階段状格子構造上での可視光応答光触媒反応
    有賀寛子; 谷池俊明; 守川春雲; MIN Byoung Koun; 唯美津木; 池田進; 斉木幸一朗; 岩澤康裕
    出版日 2006年03月13日, 日本化学会講演予稿集, 86th巻, 1号, 掲載ページ 306, 日本語, 0285-7626, 200902210240565192
  • TiO2(001)表面上における可視光応答反応とその機構解明
    有賀 寛子; 谷池 俊明; 唯 美津木; 渡辺 一也; 松本 吉泰; 池田 進; 斉木 幸一朗; 岩澤 康裕
    TiO<SUB>2</SUB>(001)単結晶表面上で酸素共存下、可視光照射によりギ酸が光分解することを見いだした。EELS、UPS、2PPES測定及びDFT計算から、この可視光応答性が発現したのは、この表面特有の階段状格子構造から由来する表面準位がbulkのband gap(3.0 eV)内に形成されたためであること、また、生成した正孔・電子の酸化還元反応の機構を明らかにした。, The Surface Science Society of Japan, 出版日 2006年, 表面科学講演大会講演要旨集, 26巻, 0号, 掲載ページ 190-190, 130004673449
  • STMによるTiO2(001)表面上でのギ酸の可視光分解反応に関する研究
    有賀寛子; 谷池俊明; 守川春雲; MIN Byoung Koun; 唯美津木; 岩沢康裕
    出版日 2005年09月20日, 触媒討論会討論会A予稿集, 96th巻, 掲載ページ 108, 日本語, 1343-9936, 200902296084197333
  • 単結晶二酸化チタンを用いた可視光応答光触媒反応
    有賀寛子; 谷池俊明; 守川春雲; MIN Byoung Koun; 唯美津木; 岩沢康裕
    出版日 2005年09月07日, 応用物理学会学術講演会講演予稿集, 66th巻, 2号, 掲載ページ 515, 日本語, 200902264901377919
  • STMを用いたTiO2(001)単結晶表面上での可視光ギ酸分解過程の研究
    有賀寛子; 生井勝康; 岩沢康裕; 守川春雲
    出版日 2005年03月11日, 日本化学会講演予稿集, 85th巻, 1号, 掲載ページ 332, 日本語, 0285-7626, 200902270468686146
  • STMによるTiO2(001)単結晶上での可視光誘起表面反応の研究
    有賀寛子; 生井勝康; 岩沢康裕
    出版日 2004年12月03日, 固体・表面光化学討論会講演要旨集, 23rd巻, 掲載ページ 90-91, 日本語, 200902229842230160
  • 可視光照射によるTiO2(001)表面上での吸着分子の光反応過程のSTM観察
    有賀寛子; 生井勝康; 岩沢康裕
    出版日 2004年09月01日, 分子構造総合討論会講演要旨集(CD-ROM), 2004巻, 掲載ページ 3P031, 日本語, 200902260667959229
  • TiO2(001)表面上のメタノールとギ酸の光酸化過程のSTM観察
    有賀寛子; 手老龍吾; 生井勝康; 岩沢康裕
    出版日 2004年03月11日, 日本化学会講演予稿集, 84th巻, 1号, 掲載ページ 123, 日本語, 0285-7626, 200902230633484667
  • TiO2(001)表面上の可視光誘起反応過程のSTM観察
    有賀 寛子; 生井 勝康; 岩澤 康裕
    当研究室で既に報告したTiO2(001)表面上の階段状格子構造を用い、メタノール・ギ酸の紫外光及び可視光照射下での光酸化反応過程をSTM観察した。我々は吸着フォルメートの光分解過程の追跡に成功し、この表面の可視光応答性発現をみいだした。これは本構造特有の表面準位により3.0 eV以下の電子励起が可能となり、同様に特有な活性点構造により吸着種間の立体的配置が満たされたことによるものと考えている。, The Surface Science Society of Japan, 出版日 2004年, 表面科学講演大会講演要旨集, 24巻, 0号, 掲載ページ 203-203, 130004673238

講演・口頭発表等

  • オペランドマルチモーダル計測による燃料電池Pt電極触媒上の吸着酸素種の挙動解明
    三輪 寛子; 吉田 健文; 金子 拓真; 佐々木 岳彦; 東 晃太朗; 坂田 智裕; 関澤 央輝; 宇留賀 朋哉; 岩澤 康裕
    日本化学会第104春季年会
    発表日 2024年03月19日
    開催期間 2024年03月18日- 2024年03月21日
  • 固体高分子形燃料電池内Ptナノ粒子表面の酸素種と硫黄種のオペランド放射光X線発光分光マルチモーダル計測評価
    三輪寛子
    第132回触媒討論会
    発表日 2023年09月13日
    開催期間 2023年09月13日- 2023年09月15日
  • 燃料電池電極触媒のオペランドHR-XANES/RIXS/QXAFS/XRDマルチモーダル計測評価
    三輪 寛子
    日本化学会第103春季年会
    発表日 2023年03月24日
    開催期間 2023年03月22日- 2023年03月25日
  • オペランドX線発光分光法による燃料電池内Ptナノ粒子表面の吸着種の解析
    三輪寛子
    第12回岩澤コンファレンス ―サステナブル社会のための触媒化学・表面科学の最前線―, 招待
    発表日 2023年03月22日
  • 燃料電池電極触媒の マルチモーダルオペランド計測
    三輪 寛子
    マテリアル先端リサーチインフラ・マテリアルの 高度循環のための技術領域セミナー, 招待
    発表日 2023年03月06日
  • μSR measurements of Photocatalyst rutile TiO2 single crystal
    有賀 寛子
    ポスター発表, 英語, The 2015 International Chemical Congress of Pacific Basin Societies (PACIFICHEM 2015), 国際会議
    発表日 2015年12月16日
  • μSR measurements of rutile TiO2 single crystal: A new method to approach in Photocatalysis
    有賀 寛子
    ポスター発表, 英語, The 17th International Symposium on Relations between Homogeneous and Heterogeneous Catalysis (ISHHC17), 国際会議
    発表日 2015年07月14日

担当経験のある科目_授業

  • インフォパ ワード・エネルギー概論
    2024年04月 - 現在
    東京外国語大学
  • 化学概論Ⅰ
    2024年04月 - 現在
    電気通信大学
  • 基礎科学実験B2(秋)
    2023年10月 - 現在
    電気通信大学
  • ラボラトリーセミナー
    北海道大学
  • 工業英語演習
    北海道大学

所属学協会

  • 触媒学会
  • 日本化学会
  • 表面科学会
  • 中間子学会

共同研究・競争的資金等の研究課題

  • 表面水素工学の学理構築と活用に関する研究総括
    森 浩亮; 青木 芳尚; 日沼 洋陽; 本倉 健; 三輪 寛子
    日本学術振興会, 科学研究費助成事業, 大阪大学, 学術変革領域研究(B), 気相の水素分子が、酸化物表面上に吸着した金属を介して高活性な単原子として流れ出し、高速に拡散する『水素スピルオーバー』現象の原理原則は未だブラックボックスである。本領域では、スピルオーバーにより生成した活性水素種を使いこなすための制御因子を正しく理解し、またその画期的な活用法の提案に取り組んだ。 実験班の森(A01)、本倉(A02)、青木(A03)は、それぞれ革新材料合成、新触媒プロセス、電気化学セルの開発に取り組み、水素スピルーバーの新たな利用法を提案した。同じく実験班の三輪(A05)は、水素様素粒子であるミュオンをプローブにスピルオーバー水素の動的な挙動を直接観察するための予備的な基礎情報取得に努めた。理論計算班の日沼(A04)は、スピルオーバーメカニズムの理論的・系統的理解を独自に進め、さらに実験班に対し理論的裏付けの提供、あるいは理論的な提言を行った。また、総括班では、全体領域会議を3 回開催し、班員間の連携の場を提供した。また、班員の研究支援として、SPring-8、KEK-PF、大阪大学超高圧電子顕微鏡センターの共同利用機器を利用できるように便宜を図った。, 21H05097
    研究期間 2021年08月23日 - 2024年03月31日
  • 表面水素工学:オペランドμSR法の開発による水素スピルオーバーの原子レベル解明
    三輪 寛子; 伊藤 孝
    日本学術振興会, 科学研究費助成事業, 電気通信大学, 学術変革領域研究(B), 21H05102
    研究期間 2021年08月23日 - 2024年03月31日
  • 超高感度全反射蛍光XAFSの開発と燃料電池白金触媒の合金効果機構の解明
    朝倉 清高; 和田 敬広; 三輪 寛子; 増田 卓也
    日本学術振興会, 科学研究費助成事業, 北海道大学, 基盤研究(A), 燃料電池白金触媒を合金化すると高活性化する。本研究では、この高活性化の要因が、電荷移動がおき、電子密度が変化するためなのか,構造が変化し、状態密度が変化するためなのかをしらべる。 そこで単結晶基板上にPdを1層から複数層載せ、その上のPtの結合距離と活性の関係を調べて、上記の学問的問いの回答を得る。 本年、いくつかの成果を得た。 PtをAu表面にSLRR(Surface Limited Redox Replacement )法でPtをAu(111)表面につけて、還元後の構造をしらべた。Pt-Ptの伸長が観測されないという結果がえられた。一方PdをAu(111)につけたものでは、Pd-Pdの伸長が観測された。 現在PtとPdの違いについて検討を加えている。一方、Arc Plasma 法で調製したPtAu合金ナノ粒子では、Au-Auが異常に短くなるという特異な現象を見出した。この時にPtAu合金ナノ粒子はPtAu合金をCoreとし、PtをShellとする構造をとっていることを見出した。一方、高電位にして、高輝度X線を照射すると、Pt Shellが選択的に溶け出すX線誘起Pt溶解現象を見出した。その結果Pt Shell により隠れていたPtAuナノ合金が表面に露出する。この時にAuーAu は通常予想されるAu-Auの結合距離まで回復することが分かった。この結果からPtのShellの強い表面張力がAu-Au の結合距離を異常に短くしたことが分かった。 こうした合金系を通常のXAFS解析を行うと情報量が足りず、無意味な解が得られることが多い。これを避けるため拘束サラーサーチ法を開発した。PtRuの構造解析に成功し、Cluster-in-Clusterであることを見出した。この研究を通じてサラサーチ法の妥当性を示す理論的バックグラウンドとしてUniform Prior Probability 原理を提案することができた。また、反応解析用の回転電極も整備した。, 20H00367
    研究期間 2020年04月01日 - 2024年03月31日
  • 新規水素発生触媒の開拓と反応機構解明
    三輪 寛子
    日本学術振興会, 科学研究費助成事業, 基盤研究(C), 2021年度は、Ni2P(10-10)面に形成する1x1構造上では当初期待していたようなPtを大幅に上回る活性を見出すことが容易ではないことがわかった。これは、当初水素の結合エネルギーから高活性と期待していたP終端表面では、表面を終端しているPと水素原子との結合と比べ、同Pと表面第二層のNiとの結合が弱いため、水素生成よりPH3脱離が優先してしまうためだと考えられる。Pが脱離しNiが露出した表面では、水素の吸着エネルギーを指標とするとそれほど高い水素生成能は期待できないことを我々は第一原理計算から既に示している。複雑な表面構造を形成する金属―典型元素化合物では、水素生成反応中に表面構造が変化することもあるため、一般的に用いられているような水素吸着エネルギーを指標としたvolcano plotから単純に触媒活性を予測することはできず、その反応経路も含めて検討する必要があることが示された。本研究のもう一つの目的は、水素生成反応の機構を解明することであるので、既に高い活性が知られているPtナノ粒子の電気化学条件下での表面状態を明らかとするためオペランド条件でのXAFS測定と第一原理計算を行った。Pt単結晶表面上では、その構造と吸着種の状態が広く研究され、既にわかっていることも多いが、実際触媒として用いられるPtナノ粒子の構造やエッジ、コーナーなどの局所構造の活性予測などはほとんど進んでいない。Pt粒子が劣化すると水酸基の吸着量が増え、一方で水素の吸着量が減少することがわかった。これらの相関の理解は、更なる第一原理計算による検討が必要であるが、Pt粒子の構造の制御が水素生成能の向上に必要であると考えられる。今後、Pt粒子の準安定構造を含め、様々な構造について、水素の吸着状態を明らかとしていくことが課題と考えられる。, 19K05379
    研究期間 2019年04月01日 - 2023年03月31日
  • 表面合金ナノ粒子の精密調製と触媒特性に関する研究
    有賀 寛子
    文部科学省, 科学研究費補助金(若手研究(B)), 北海道大学, 若手研究(B), 担持合金ナノ粒子の触媒特性を原子・分子レベルで解明することは、新規高性能触媒を設計するための基礎となる重要な研究課題の一つである。担持合金ナノ粒子の触媒活性は、合金ナノ粒子の粒径・内部構造・電子状態、金属ナノ粒子と担体の相互作用、担体の表面構造など、多くの要因が絡み合って創出される。このような現象を原子レベルで理解するには、原子レベルで構造が既知である単結晶表面上に、触媒の活性点構造をモデル化することが有効である。本研究では、配位不飽和Tiが配列し、触媒担体表面として期待されるTiO2(110)-1x2表面構造をサブÅの分解能で明らかとした。また、TiO2の新しい欠陥構造も明らかとした。, 15K17839
    研究期間 2015年 - 2016年
  • μSR法を用いた金属酸化物の光触媒特性の解明
    有賀 寛子
    文部科学省, 科学研究費補助金(新学術領域研究(研究領域提案型)), 北海道大学, 新学術領域研究(研究領域提案型), 光触媒であるTiO2内の欠陥は,光吸収や電子伝達に重要な役割を果たす。この欠陥には水素が安定化するということが理論計算で予測されているため、本研究では、muonをプローブとしてTiO2の欠陥を観測できないかと考えた。muonは水素と同じ電荷を有する量子であるため,物質中で水素の軽い同位体として振る舞う。また,平均2.2 μsで崩壊するため,崩壊の時に放出される陽電子を観測することで,物質内でのmuon (つまり水素)の分布や電子状態を明らかとすることができる。 本研究では、rutile型TiO2に酸素欠陥を導入しmuon spin rotation/relaxation法を用いて観測し、得られたスペクトルを詳細に解析することで、ruitle型TiO2内部の欠陥として、酸素欠陥に二つの水素が存在する新しい安定構造を見出した(測定では水素とミュオンの安定構造を観測した)。また、この構造について密度汎関数法によりエネルギー的安定性と電子状態を計算したところ、本構造は準安定構造の一つで、また、band gap内部にエネルギー状態を持つことが明らかとなった。これは、本構造がrutile型TiO2の光触媒特性に寄与していることを示唆する。 以上のように、本研究では、光触媒特性の予測に、muonをプローブとして用いることが有効であることを示した。更に、金属酸化物内部の新しい水素種の存在を示唆した。本結果は、muon spin rotation/relaxation法が、今後、より複雑な構造を有する高機能、多機能な光触媒に応用可能で、予測が困難な光触媒特性を発現している原子レベルの構造、電子状態分布を明らかとするツールとなることを示している。, 26108701
    研究期間 2014年 - 2015年
  • 金属ナノ粒子の水素化触媒反応特性の原子レベル解明
    有賀 寛子
    文部科学省, 科学研究費補助金(新学術領域研究(研究領域提案型)), 北海道大学, 新学術領域研究(研究領域提案型), 本年度は,TiO2内に存在する酸素欠陥に捕捉されたmuonには,室温付近で電子を非常に弱く束縛した状態があることを見出した.Muonは水素様粒子として知られており,平均寿命2.2 μsで崩壊する時,主にスピン方向に陽電子を放出するため,崩壊直前のmuonのスピンの向きを観測することができる.そのため,外部磁場による摂動を加えることでmuonの電荷状態を知ることができる.このような性質を使い,触媒や光触媒内部での水素の分布や電荷分布を明らかにしていくことを,本研究の目的としている.我々は,まず,触媒担体や光触媒として広く用いられているTiO2内の水素,更に,欠陥構造内の水素の状態を明らかとすることとした.TiO2内の水素や欠陥構造内は,band gap内,もしくは,band gap付近にエネルギー準位を有するため,TiO2全体の物性や化学特性を大きく変化させることが知られており,これらを制御することが求められているが、電子状態の空間分布など基礎的なことがわかっていないのが現状である。そこで、muonをプローブとした測定を行った.試料は,構造の制御が比較的容易な単結晶基板を用いた.外部磁場(縦磁場、横磁場)を印加しながら,muonの回転を観測する(μSR法)ことで,酸素欠陥でmuonが安定化(準安定)すると,これまで考えられていなかった,muonに非常に弱く束縛された電子が室温付近で存在することがわかった.これは,酸素欠陥に水素が補足されると伝導帯に近いエネルギー準位を持つshallow stateを形成することを示唆している。欠陥と水素が導入されたTiO2は,特異な物性や光触媒能を示すことが近年報告されているが,本年度,新しく見出したstateが,これらの起源の一つである可能性が高い.このように、一つ一つの性質の起源を原子レベルで解明していくとこで,TiO2を始めとする,触媒や光触媒の機能の制御に繋がるものと考えられる。, 24108501
    研究期間 2012年 - 2013年
  • 金属原子数を制御した精密担持金属触媒の開発と最も活性な金属原子数・界面構造の決定
    高草木 達; 角山 寛規; 朝倉 清高; 有賀 寛子
    日本学術振興会, 科学研究費助成事業, 北海道大学, 基盤研究(C), 実用上重要な酸化物担持金属触媒の特性(活性・選択性)は、金属クラスターのサイズや酸化物担体担体との相互作用に強く依存する。本研究では、単原子から10 nmまでのサイズの金クラスターを、サイズ分布の小さな状態で二酸化チタン単結晶表面へ担持するための方法論の開発を試み、担持後のクラスターに関してSTM/AFMや偏光全反射蛍光XAFS等の表面科学的手法を適用して、原子レベルの構造評価を行った。また構造と活性の相関を得るために、単結晶表面での触媒反応測定のための超高真空装置を開発した。, 23550001
    研究期間 2011年 - 2013年
  • 表面金属ナノクラスター精密調製と構造物性の研究
    朝倉 清高; 有賀 寛子
    日本学術振興会, 科学研究費助成事業, 北海道大学, 特定領域研究, 電位、総電荷量、イオン濃度などをパラメータとして、TiO_2(110)表面に電気化学的手法によって、金属クラスターを形成させ、そのサイズ、形、露出結晶面をSTMや偏光全反射蛍光XAFS法で調べて、表面クラスターの構造を原子レベルで決定し、ナノクラスター構造の制御を目的に実験を展開した。 その結果、印加電圧により、粒径や成長様式の異なるPtを得ることができた。具体的には、ポテンシャルをAg/AgCl電極に対して、-0.05Vにしたときには、数nm程度のPt粒子が成長するのに対して、-0.15Vでは、20-40nmにわたる粒径をもつナノ粒子が形成された。このように、粒子径をポテンシャルやそのかける時間で制御できることがわかった。一方、Ptの析出するサイトについてのポテンシャル依存性は認められなかった。すなわち、ステップおよびテラスにPtナノクラスターが均一に分布し、Underpotential電位での析出は観測することができなかった。 また表面をメルカプト安息香酸で修飾した表面においては、CuやAuが単原子状に高分散できることをみいだした。 これは、SとCuとの強い相互作用に起因するものである。微粒子になりやすいAuについてもメルカプト安息香酸で修飾することで、高分散化することが可能であることがわかった。こうしたメルカプト安息香酸による表面の修飾は、新しい金属高分散化法として、期待される。 また、ステップを多数持つ表面においては、Niがステップとの相互作用により、1次元小クラスターとなることが見いだされた。さらにAuのナノ粒子を酸素プラズマで処理すると、表面Auナノクラスターのサイズが小さくなることがわかった。 以上の成果は表面のナノ構造をもつクラスター制御の新しい方法論を提供したものといえる。, 22015002
    研究期間 2010年 - 2011年