Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Miho Yamauchi Last modified date:2022.06.17

Professor / Department of Applied Molecular Chemistry / Institute for Materials Chemistry and Engineering

1. Akihiko Anzai, Ming-Han Liu, Kenjiro Ura, Tomohiro G. Noguchi, Akina Yoshizawa, Kenichi Kato, Takeharu Sugiyama, Miho Yamauchi, Cu Modified TiO2 Catalyst for Electrochemical Reduction of Carbon Dioxide to Methane, Catalysts, 10.3390/catal12050478, 12, 5, 478-478, 2022.04, Electrochemical reduction of CO2 (ECO2R) is gaining attention as a promising approach to store excess or intermittent electricity generated from renewable energies in the form of valuable chemicals such as CO, HCOOH, CH4, and so on. Selective ECO2R to CH4 is a challenging target because the rate-determining step of CH4 formation, namely CO* protonation, competes with hydrogen evolution reaction and the C–C coupling toward the production of longer-chain chemicals. Herein, a Cu-TiO2 composite catalyst consisting of CuOx clusters or Cu nanoparticles (CuNPs), which are isolated on the TiO2 grain surface, was synthesized using a one-pot solvothermal method and subsequent thermal treatment. The Cu-TiO2 catalyst exhibited high selectivity for CH4, and the ratio of FE for CH4 to total FE for all products in ECO2R reached 70%..
2. Sho Kitano, Tomohiro G. Noguchi, Masamichi Nishihara, Kazutaka Kamitani, Takeharu Sugiyama, Satoru Yoshioka, Tetsuya Miwa, Kazunari Yoshizawa, Aleksandar Staykov, Miho Yamauchi, Heterointerface Created on Au‐Cluster‐Loaded Unilamellar Hydroxide Electrocatalysts as a Highly Active Site for the Oxygen Evolution Reaction, Advanced Materials, 10.1002/adma.202110552, 2110552-2110552, 2022.03.
3. David S. Rivera Rocabado, Mika Aizawa, Tomohiro G. Noguchi, Miho Yamauchi, Takayoshi Ishimoto, Uncovering the Mechanism of the Hydrogen Poisoning on Ru Nanoparticles via Density Functional Theory Calculations, Catalysts, 10.3390/catal12030331, 12, 3, 331-331, 2022.03, Although hydrogen plays a crucial role in ammonia synthesis, very little is known about its poisoning of Ru catalysts. In this study, density functional theory calculations of H2 and N2 dissociations, and H atom binding on Ru153 were performed to provide a fundamental understanding of hydrogen poisoning. Because of the kinetic dominance of the H2 dissociation over N2 (vertically or horizontally adsorbed) splitting, the dissociated H atoms block the active sites required for horizontal (less energetically demanding dissociation) N2 adsorption to occur either from the gas phase or after its geometrical transformation from being adsorbed vertically. Additionally, the dissociated H atoms withdraw electrons from the surface, which reduces the ability of the neighboring Ru atoms to donate electrons for N2 activation, hindering its dissociation and suppressing ammonia synthesis..
4. Hiroto Eguchi, Takashi Kobayashi, Teppei Yamada, David S. Rivera Rocabado, Takayoshi Ishimoto, Miho Yamauchi, Inversely polarized thermo-electrochemical power generation via the reaction of an organic redox couple on a TiO2/Ti mesh electrode, Scientific Reports, 10.1038/s41598-021-93269-7, 11, 1, 2021.12, Abstract

We demonstrate thermo-electrochemical (TEC) conversion using a biocompatible redox couple of lactic acid and pyruvic acid on earth-abundant TiO2. The TEC cell exhibited a positive Seebeck coefficient of 1.40 mV K−1. DFT calculations figured out that the adsorption of intermediate species and protons on TiO2 controls both the redox reaction and current polarity..
5. N. Oshime, K. Ohwada, K. Sugawara, T. Abe, R. Yamauchi, T. Ueno, A. Machida, T. Watanuki, S. Ueno, I. Fujii, S. Wada, R. Sato, T. Teranishi, M. Yamauchi, K. Ishii, H. Toyokawa, K. Momma, Y. Kuroiwa,, Bragg coherent diffraction imaging allowing simultaneous retrieval of three-dimensional shape and strain distribution for 40-500-nm particles, J. J. Appl. Phys., 60, SFFA07 (2021).,, 60, SFFA07-SFFA07, 2021.10.
6. Sho Kitano, Mei Lee Ooi, Tomokazu Yamamoto, Syo Matsumura, Miho Yamauchi, Catalytic roles and synergetic effects of iron-group elements on monometals and alloys for electrochemical oxidation of ammonia, Bull. Chem. Soc. Jpn.,, 94, 4, 1292-1299, 2021.05.
7. Miho Isegawa, Aleksandar Staykov, Miho Yamauchi, Proton-Coupled Electron Transfer in Electrochemical Alanine Formation from Pyruvic Acid: Mechanism of Catalytic Reaction at Interface between TiO2 (101) and Water, J. Phys. Chem. C, 2021.05.
8. S. Yoshimaru, M. Sadakiyo, N. Maeda, M. Yamauchi, K. Kato, Jenny Pirillo, Y. Hijikata, Support Effect of Metal−Organic Frameworks on Ethanol
Production through Acetic Acid Hydrogenatio, ACS Appl. Mater. Interfaces, 13, 17, 19992-200001, 2021.04.
9. Xuemei Liao, Yonghui Zhao, Changwen Liu, Xiaopeng Li, Yu Sun, Kenichi Kato, Miho Yamauchi, Zheng Jiang, Low temperature surface oxygen activation in crystalline MnO2
triggered by lattice confined Pd single atoms, J. Energ. Chem.,, 62, 136-144, 2021.03.
10. M. Liu, S. Hu, Y. Zhang, C. Zhao, W. Jiang, C. Qi, X. Zhu, P. Qiu, Y. Sun, K. Kato, Y. Zhao, X. Li, M. Yamauchi, W. Luo, Atomistic Site Control of Pd in Crystalline MnO2 Nanofiber for Enhanced Electrocatalysis, Adv. Maters. Interfaces., DOI 10.1007/s10800-020-01428-x, 51, 99-106, 2021.02.
11. Nating Yang, Yonghui Zhao, Hao Zhang, Weikai Xiang, Yuhan Sun, Shuai Yang, Yu Sun, Gaofeng Zeng, Kenichi Kato, Xiaopeng Li, Miho Yamauchi, Zheng Jiang, Tong Li, Sintering Activated Atomic Palladium Catalysts with High-Temperature Tolerance of ~1,000 °C, Cell Rep. Phys. Sci., 2, 100287, 2021.02.
12. T. Fukushima, M. Yamauchi, Electrosynthesis of Glycine from Bio-derivable Oxalic Acid, J. Appl. Electrochem., DOI : 10.1007/s10800-020-01428-x, 2020.05, Electrochemical hydrogenation of non-fossil resources to produce value added chemicals has great potential to contribute to realization of sustainable material supply. We previously demonstrated that TiO2 catalyzed electrochemical reduction of biomass-derivable a-keto acid in the presence of NH3 or NH2OH affords the amino acid production. In this work, we focused on oxalic acid, which is producible by chemical degradation of agro wastes, as a starting material for the electrosynthesis of an amino acid. We examined the electrocatalytic properties of various materials, including Cu, Pt, Ti foils, calcined Al, Co, Mo, Nb, Ni, Ti, V, W, Zr foils, and some TiO2 catalysts, by conducting cyclic voltammetry (CV) measurements, and found that Mo and Ti foil calcined at 450 ºC show favorable catalytic features for the one-step glycine electrosynthesis from oxalic acid and NH2OH. Electrochemical reduction of oxalic acid at an applied potential of –0.7 V using calcined Ti foil resulted in formation of glycine and glyoxylic acid oxime, i.e., intermediate of the glycine formation, with moderate Faradaic efficiency of 28 and 28%, respectively..
13. Jun Yang, Junfang Cheng, Jie Tao, Manabu Higashi, Miho Yamauchi, Naotoshi Nakashima, Wrapping Multiwalled Carbon Nanotubes with Anatase Titanium Oxide for the Electrosynthesis of Glycolic Acid, ACS Applied Nano Materials, 10.1021/acsanm.9b01357, 2, 10, 6360-6367, 2019.10, The construction of an efficient electrocatalyst is of significant importance for electrochemical devices. In this study, a facile preparation method is developed to wrap pristine multiwalled carbon nanotubes (MWNTs) by an anatase TiO2 layer with the assistance of pyridine-based polybenzimidazole (PyPBI) The factors dominating the morphology of the obtained MWNT/PyPBY/TiO2 products, involving the employment of PyPBI and the post-treatment method, are investigated in detail. Furthermore, a self-standing electrode film is prepared via a filtration route. The electrode film is composed of a MWNT/PyPBI/TiO2 catalyst layer and a MWNT current collecting layer. The resultant electrocatalysts and electrode film with the MWNT/PyPBI/TiO2 catalyst are evaluated for the electroreduction of oxalic acid (OX) to glycolic acid (GC). By using the optimized electrode film with the MWNT/PyPBI/TiO2 catalyst, the conversion rate of OX and the selectivity of GC reach 51.2% and 38.7%, respectively..
14. Junfang Cheng, Jun Yang, Sho Kitano, Gergely Juhasz, Manabu Higashi, Masaaki Sadakiyo, Kenichi Kato, Satoru Yoshioka, Takeharu Sugiyama, Miho Yamauchi, Naotoshi Nakashima, Impact of Ir-Valence Control and Surface Nanostructure on Oxygen Evolution Reaction over a Highly Efficient Ir-TiO2 Nanorod Catalyst, ACS Catalysis, 10.1021/acscatal.9b01438, 9, 8, 6974-6986, 2019.08, Iridium oxide (IrOx)-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrOx-TiO2-Ti (ITOT), with a high concentration of active OH species and mixed valence IrOx on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm-2) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm-2 for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity..
15. H. Razavi-Khosroshahi,* S. Mohammadzadeh, M. Hojamberdiev, S. Kitano, M. Yamauchi, M. Fuji, Visible Light Active Bi3TaO7 Nanosheets for Water Splitting, Dalton Trans., 2019.05.
16. K. Edalati,* Q. Wang,* H. Eguchi, H. Razavi-Khosroshahi, H. Emami, M. Yamauchi, M. Fuji, Z. Horita, Impact of TiO2-II Phase Stabilized in Anatase Matrix by High Pressure Torsion on Electrocatalytic Hydrogen Production, Mater. Res. Lett., 2019.04.
17. Kenichi Yatsugi, Toshitaka Ishizaki, Kunio Akedo, Miho Yamauchi, Composition-controlled synthesis of solid-solution Fe–Ni nanoalloys and their application in screen-printed magnetic films, Journal of Nanoparticle Research, 10.1007/s11051-019-4497-2, 21, 3, 2019.03, Screen printing is attracting attention as a method for manufacturing magnetic components such as on-chip transformers and inductors. Fe–Ni alloys, which have high saturation magnetizations and permeabilities, are suitable as magnetic materials for screen-printed high-frequency devices. Here, we demonstrate the fabrication of a screen-printed film comprising solid-solution Fe–Ni nanoalloys, which can achieve enhanced permeability and reduced eddy-current losses in high-frequency regions. The Fe–Ni nanoalloys were prepared by chemical reduction using sodium borohydride as a reducing reagent followed by hydrogen reduction. X-ray diffraction measurements, electron microscopy, and inductively coupled plasma spectroscopy revealed that well-mixed FexNi100−x nanoalloys (x = 40, 21.5, and 10) with grain sizes of ~ 10 nm were synthesized. The obtained nanoalloys showed high saturation magnetizations comparable to bulk alloys. The screen-printed film using the Fe21.5Ni78.5 nanoalloy exhibited the highest permeability of the nanoalloy films. The eddy-current loss was suppressed by the synthesis of nanoscale-grained nanoalloys. The permeability was sufficiently high for application in transformers and inductors..
18. K. Ghuman, K. Tozaki, M. Sadakiyo, S. Kitano, T. Oyabe, M. Yamauchi, Tailoring Widely Used Ammonia Synthesis Catalysts for H and N Poisoning Resistance, Phys. Chem. Chem. Phys., 2019.01.
19. Xuemei Liao, Jindou Hou, Ya Wang, Hao Zhang, Yu Sun, Xiaopeng Li, Siyang Tang, Kenichi Kato, Miho Yamauchi, Zheng Jiang, An active, selective, and stable manganese oxide-supported atomic Pd catalyst for aerobic oxidation of 5-hydroxymethylfurfural, Green Chemistry, 10.1039/c9gc01674k, 21, 15, 4194-4203, 2019.01, Here we report for the first time a Pd-MnO2 catalyst with a single-atom feature that can convert 5-hydroxylmethyfurfural (HMF) into the important bioplastic building block 2,5-furandicarboxylic acid (FDCA) with a high yield of 88% in aqueous solution using O2 as an oxidant at ambient pressure. Pd-MnO2 shows higher activity in the productivity of FDCA (100.91 mmol h-1 gPd-1) than its Pd nanoparticle counterpart (45.57 mmol h-1 gPd-1) and state-of-the-art Pd-based catalysts. Pd-MnO2 displays promising recyclability with no degradation after five catalytic runs. Experimental and theoretical results suggest that the single-atom Pd sites that have enhanced binding affinity to HMF and their surrounding sites on the MnO2 support work synergistically toward HMF oxidation..
20. M. Yamauchi, S. Hata, H. Eguchi, S. Kitano, T. Fukushima, M. Higashi, M. Sadakiyo, K. Kato, Catalytic enhancement on Ti-Zr complex oxide particles for electrochemical hydrogenation of oxalic acid to produce an alcoholic compound by controlling electronic states and oxide structures, Catalysis Science and Technology, 10.1039/c9cy01541h, 9, 23, 6561-6565, 2019.01, Ti1-xZrxO2 complex oxide particles with 0.02 ≤ x ≤ 0.1 show superior catalytic performances for the direct power storage into glycolic acid via electroreduction of oxalic acid. The atomic pair distribution function analysis of X-ray total scatterings suggested that structural periodicity is the key factor for the catalytic enhancement..
21. Masaaki Sadakiyo, Shinichi Hata, Takashi Fukushima, Gergely Juhász, Miho Yamauchi, Electrochemical hydrogenation of non-aromatic carboxylic acid derivatives as a sustainable synthesis process
From catalyst design to device construction, Physical Chemistry Chemical Physics, 10.1039/c8cp07445c, 21, 11, 5882-5889, 2019.01, Electrochemical hydrogenation of a carboxylic acid using water as a hydrogen source is an environmentally friendly synthetic process for upgrading bio-based chemicals. We systematically studied electrochemical hydrogenation of non-aromatic carboxylic acid derivatives on anatase TiO 2 by a combination of experimental analyses and density functional theory calculations, which for the first time shed light on mechanistic insights for the electrochemical hydrogenation of carboxylic acids. Development of a substrate permeable TiO 2 cathode enabled construction of a flow-type electrolyser, i.e., a so-called polymer electrode alcohol synthesis cell (PEAEC) for the continuous synthesis of an alcoholic compound from a carboxylic acid. We demonstrated the highly efficient and selective conversion of oxalic acid to produce glycolic acid, which can be regarded as direct electric power storage into an easily treatable alcoholic compound..
22. Takashi Fukushima, Miho Yamauchi, Electrosynthesis of amino acids from biomass-derivable acids on titanium dioxide, Chemical Communications, 10.1039/c9cc07208j, 55, 98, 14721-14724, 2019.01, Seven amino acids were electrochemically synthesized from biomass-derivable α-keto acids and NH2OH with faradaic efficiencies (FEs) of 77-99% using an earth-Abundant TiO2 catalyst. Furthermore, we newly constructed a flow-Type electrochemical reactor, named a "polymer electrolyte amino acid electrosynthesis cell", and achieved continuous production of alanine with an FE of 77%..
23. Takashi Fukushima, Sho Kitano, Shinichi Hata, Miho Yamauchi, Carbon-neutral energy cycles using alcohols, Science and Technology of Advanced Materials, 10.1080/14686996.2018.1426340, 19, 1, 142-152, 2018.12, We demonstrated carbon-neutral (CN) energy circulation using glycolic acid (GC)/oxalic acid (OX) redox couple. Here, we report fundamental studies on both catalyst search for power generation process, i.e. GC oxidation, and elemental steps for fuel generation process, i.e. OX reduction, in CN cycle. The catalytic activity test on various transition metals revealed that Rh, Pd, Ir, and Pt have preferable features as a catalyst for electrochemical oxidation of GC. A carbon-supported Pt catalyst in alkaline conditions exhibited higher activity, durability, and product selectivity for electrooxidation of GC rather than those in acidic media. The kinetic study on OX reduction clearly indicated that OX reduction undergoes successive two-electron reductions to form GC. Furthermore, application of TiO2 catalysts with large specific area for electrochemical reduction of OX facilitates the selective formation of GC..
24. W. Xiang, Y. Zhao, Z. Jiang, X. Li, H. Zhang, Y. Sun, Z. Ning, F. Du, P. Gao, J. Qian, K. Kato, M. Yamauchi, Y. Sun, Palladium Single Atoms Supported by Interwoven Carbon Nanotube and Manganese Oxide Nanowire Networks for Enhanced Electrocatalysis, J. Mater. Chem. A, 2018.10.
25. Nobuki Ozawa, Shigeki Chieda, Yuji Higuchi, Tatsuya Takeguchi, Miho Yamauchi, Momoji Kubo, First-principles calculation of activity and selectivity of the partial oxidation of ethylene glycol on Fe(0 0 1), Co(0 0 0 1), and Ni(1 1 1), Journal of Catalysis, 10.1016/j.jcat.2018.03.017, 361, 361-369, 2018.05, To recycle ethylene glycol (HOCH2CH2OH) fuel in alkaline fuel cells, active and selective catalysts for partially oxidizing HOCH2CH2OH to glycolic acid (HOCH2COOH) and oxalic acid ((COOH)2) are required at the anode; in other words, complete oxidation of HOCH2CH2OH to CO2 prevents ethylene glycol recycling. We investigate catalyst activity and selectivity for oxidizing HOCH2CH2OH to HOCH2COOH on Fe(0 0 1), Co(0 001), and Ni(1 1 1) via first-principles calculations. We calculate the oxidation reaction path from HOCH2CH2OH to HOCH2COOH without C–C bond dissociation to avoid CO2 generation. Partial oxidation of HOCH2CH2OH to HOCH2COOH without C–C bond dissociation proceeds as follows: O–H bond dissociation of HOCH2CH2OH to generate HOCH2CH2O; C–H bond dissociation of HOCH2CH2O to generate HOCH2CHO; C–H bond dissociation of HOCH2CHO to generate HOCH2CO; and OH addition to HOCH2CO to generate HOCH2COOH. The activation energies for O–H bond dissociation of HOCH2CH2OH and C–H bond dissociation of HOCH2CH2O and HOCH2CHO on Fe(0 0 1) are 20.2, 22.8, and 35.2 kcal/mol, respectively, which are the lowest of the three surfaces. Thus, Fe(0 0 1) is most active. To determine the selectivity, we compare the bond dissociation activation energies. The activation energies for C–C bond dissociation of HOCH2CH2OH and HOCH2CH2O on Fe(0 0 1) (66.7 and 39.5 kcal/mol, respectively) are higher than those for O–H bond dissociation of HOCH2CH2OH (20.2 kcal/mol) and C–H bond dissociation of HOCH2CH2O (22.8 kcal/mol), implying that the O–H bond of HOCH2CH2OH and C–H bond of HOCH2CH2O dissociate before the C–C bond dissociation during oxidation on Fe(0 0 1). In contrast, the activation energies for C–H and C–C bond dissociation of HOCH2CHO (35.2 and 32.8 kcal/mol, respectively) are similar. The C–H and C–C bonds therefore dissociate during HOCH2CHO oxidation. On Co(0 0 0 1) and Ni(1 1 1), the activation energies for C–C bond dissociation of HOCH2CH2O and HOCH2CHO are lower than those for their C–H bond dissociation. Therefore, Fe(0 0 1) is more active and selective than Co(0 0 0 1) and Ni(1 1 1) for the partial oxidation of HOCH2CH2OH to HOCH2COOH..
26. H. Kobayashi, M. Yamauchi, R. Ikeda, T. Yamamoto, S. Matsumura, H. Kitagawa, Double enhancement of hydrogen storage capacity of Pd nanoparticles by 20 at% replacement with Ir, Chem. Sci., 2018.05.
27. Masaaki Sadakiyo, Shinichi Hata, Xuedong Cui, Miho Yamauchi, Electrochemical Production of Glycolic Acid from Oxalic Acid Using a Polymer Electrolyte Alcohol Electrosynthesis Cell Containing a Porous TiO2 Catalyst, Scientific Reports, 10.1038/s41598-017-17036-3, 7, 1, 2017.12, A liquid flow-Type electrolyser that continuously produces an alcohol from a carboxylic acid was constructed by employing a polymer electrolyte, named a polymer electrolyte alcohol electrosynthesis cell (PEAEC). Glycolic acid (GC, an alcoholic compound) is generated on anatase TiO2 catalysts via four-electron reduction of oxalic acid (OX, a divalent carboxylic acid), accompanied with water oxidation, which achieves continuous electric power storage in easily stored GC. Porous anatase TiO2 directly grown on Ti mesh (TiO2/Ti-M) or Ti felt (TiO2/Ti-F) was newly fabricated as a cathode having favourable substrate diffusivity. A membrane-electrode assembly composed of the TiO2/Ti-M, Nafion 117, and an IrO2 supported on a gas-diffusion carbon electrode (IrO2/C) was applied to the PEAEC. We achieved a maximum energy conversion efficiency of 49.6% and a continuous 99.8% conversion of 1 M OX, which is an almost saturated aqueous solution at room temperature..
28. Miho Yamauchi, Sho Kitano, Masaaki Sadakiyo, Inorganic nanocatalysts for the electronic power circulation using alcohol/carboxylic acid redox couples, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 254, 2017.08.
29. Sho Kitano, Masaaki Sadakiyo, Kenichi Kato, Miho Yamauchi, Hiroyuki Asakura, Tsunehiro Tanaka, Keiji Hashimoto, Hiroshi Kominami, Effects of the structure of the Rh3+modifier on photocatalytic performances of an Rh3+/TiO2photocatalyst under irradiation of visible light, Applied Catalysis B: Environmental, 10.1016/j.apcatb.2016.12.047, 205, 340-346, 2017.01, For a rhodium ion-modified TiO2(Rh3+/TiO2) photocatalyst responding to visible light, control of the structure of the Rh3+modifier and effects of the structures of the Rh3+modifier on photocatalytic activities were examined. A TiO2support was pre-calcined to maintain crystallinity and specific surface area during post-calcination, and the structure of the Rh3+modifier for Rh3+/TiO2was changed by post-calcination without causing changes in the crystallinity and specific surface area of the TiO2support. In mineralization of acetone under irradiation of visible light, the photocatalytic activities of the post-calcined Rh3+/TiO2showed a volcano-like tendency as a function of post-calcination temperature. The results of this study showed that an atomically isolated structure of the Rh3+modifier was preferable for high activities and that aggregation of the Rh species led to a decrease in the activities..
30. Sichao Ma, Masaaki Sadakiyo, Minako Heim, Raymond Luo, Richard T. Haasch, Jake I. Gold, Miho Yamauchi, Paul J.A. Kenis, Electroreduction of carbon dioxide to hydrocarbons using bimetallic Cu-Pd catalysts with different mixing patterns, Journal of the American Chemical Society, 10.1021/jacs.6b10740, 139, 1, 47-50, 2017.01, Electrochemical conversion of CO2 holds promise for utilization of CO2 as a carbon feedstock and for storage of intermittent renewable energy. Presently Cu is the only metallic electrocatalyst known to reduce CO2 to appreciable amounts of hydrocarbons, but often a wide range of products such as CO, HCOO-, and H2 are formed as well. Better catalysts that exhibit high activity and especially high selectivity for specific products are needed. Here a range of bimetallic Cu-Pd catalysts with ordered, disordered, and phase-separated atomic arrangements (Cuat:Pdat = 1:1), as well as two additional disordered arrangements (Cu3Pd and CuPd3 with Cuat:Pdat = 3:1 and 1:3), are studied to determine key factors needed to achieve high selectivity for Cl or C2 chemicals in CO2 reduction. When compared with the disordered and phase-separated CuPd catalysts, the ordered CuPd catalyst exhibits the highest selectivity for Cl products (>80%). The phase-separated CuPd and Cu3Pd achieve higher selectivity (>60%) for C2 chemicals than CuPd3 and ordered CuPd, which suggests that the probability of dimerization of Cl intermediates is higher on surfaces with neighboring Cu atoms. Based on surface valence band spectra, geometric effects rather than electronic effects seem to be key in determining the selectivity of bimetallic Cu-Pd catalysts. These results imply that selectivities to different products can be tuned by geometric arrangements. This insight may benefit the design of catalytic surfaces that further improve activity and selectivity for CO2 reduction..
31. Hadi Razavi-Khosroshahi, Kaveh Edalati, Ji Wu, Yuki Nakashima, Makoto Arita, Yoshifumi Ikoma, Masaaki Sadakiyo, Yuji Inagaki, Aleksandar Tsekov Staykov, Miho Yamauchi, Zenji Horita, Masayoshi Fuji, High-pressure zinc oxide phase as visible-light-active photocatalyst with narrow band gap, Journal of Materials Chemistry A, 10.1039/c7ta05262f, 5, 38, 20298-20303, 2017.01, Wide band gap of pure ZnO with wurtzite crystal structure (3.1-3.4 eV) limits its photocatalytic activity to the ultraviolet (UV) region of solar spectrum. High-pressure rocksalt polymorph of ZnO can theoretically show narrow band gap; however, the rocksalt phase is unstable at ambient pressure. Herein, rocksalt phase with large fractions of oxygen vacancies is successfully stabilized at ambient conditions by inducing plastic strain in pure ZnO under 6 GPa using the High-Pressure Torsion (HPT) method. Formation of rocksalt phase reduces the band gap of ZnO to 1.8 eV, which is in good agreement with the first-principles calculations, and significantly improves the photocatalytic activity under visible light..
32. Masaaki Sadakiyo, Takahiro Kuramoto, Kenichi Kato, Miho Yamauchi, Introduction of an amino group on zeolitic imidazolate framework through a ligand-exchange reaction, Chemistry Letters, 10.1246/cl.170323, 46, 7, 1004-1006, 2017.01, We newly synthesized an amino-functionalized zeolitic imidazolate framework (ZIF), [Zn{(dmamIM)n(mIM)m}2] (dmamIM-: 2-[(dimethylamino)methyl]imidazolate; mIM-: 2- methylimidazolate), through a ligand-exchange reaction using an amino-functionalized ligand, dmamIM-, and ZIF-8 as a mother framework. Original ligand of ZIF-8, mIM-, was partially replaced with the dmamIM-under various solvothermal conditions. The crystal structures of resultant specimens were analyzed by Rietveld method combined with maximum entropy method using synchrotron X-ray powder diffraction patterns. Porous characters of the compound were examined using adsorption measurements and alternate-current impedance measurements. The ligand exchange was found to occur as an equilibrium reaction in the reaction solutions. The reaction rate deeply depends on the types of solvents and the introduced ligands are homogeneously distributed on the sodalite-type framework..
33. Shotaro Yoshimaru, Masaaki Sadakiyo, Aleksandar Tsekov Staykov, Kenichi Kato, Miho Yamauchi, Modulation of the catalytic activity of Pt nanoparticles through charge-transfer interactions with metal-organic frameworks, Chemical Communications, 10.1039/c7cc02829f, 53, 50, 6720-6723, 2017.01, We employed metal-organic framework (MOF) supports to modulate the electronic states of loaded Pt nanoparticles (NPs) in their composite catalysts (Pt/MOFs). Pt NPs were homogenously deposited on four MOFs characterized with different electronic states (Zn-MOF-74, Mg-MOF-74, HKUST-1, and UiO-66-NH2). Theoretical and experimental studies demonstrated that a charge-transfer interaction between Pt NPs and MOFs is a critical factor for controlling the catalytic activity of Pt NPs supported on MOFs..
34. Miho Yamauchi, T Kuramoto, Masaaki Sadakiyo, Crystal structure of poly[tris (μ-2-dimethylaminomethyl imidazolato) nitratodizinc(II)], 2016.11, Crystal structure of poly[tris (μ-2-dimethylaminomethyl imidazolato) nitratodizinc(II)].
35. Miho Yamauchi, 北野 翔, 秦 慎一, 渡邉 亮太, Masaaki Sadakiyo, Kenichi Kato, Masaki Takaka, Hydrogenation of oxalic acid using light-assisted water electrolysis for the production of an alcoholic compound, Green Chem., 18, 3700-3706, 2016.10, Hydrogenation of oxalic acid using light-assisted water electrolysis for the production of an alcoholic compound.
36. Miho Yamauchi, S. Ma, Masaaki Sadakiyo, R. Luoa, P. Kenis, One-step electrosynthesis of ethylene and ethanol from CO2 in an alkaline electrolyzer, J. Power Sources, 310, 219-228, 2016.10, One-step electrosynthesis of ethylene and ethanol from CO2 in an alkaline electrolyzer.
37. Miho Yamauchi, K. Kato, H. Kasai, H. Hori, M. Takata, N. Ozawa, M. Kubo, T. Takeguchi, Masaaki Sadakiyo, Superionic conduction in Co-Vacant P2-NaxCoO2 created by the hydrogen reductive elimination, Chem. Asian J, 10, 1537-1541, 2016.10, Superionic conduction in Co-Vacant P2-NaxCoO2 created by the hydrogen reductive elimination.
38. Miho Yamauchi, Nobuki Ozawa, Momoji Kubo, Experimental and Quantum Chemical Approaches to Develop Highly Selective Nanocatalysts for CO2-free Power Circulation, Chemical Record, 10.1002/tcr.201600047, 16, 5, 2249-2259, 2016.10, Renewable electricity must be utilized to usefully suppress the atmospheric CO2 concentration and slow the progression of global warming. We have thus proposed a new concept involving CO2-free electric power circulation systems via highly selective electrochemical reactions of alcohol/carboxylic acid redox couples. Design concepts for nanocatalysts able to catalyze highly selective electrochemical reactions are provided from both experimental and quantum mechanical perspectives..
39. Hadi Razavi-Khosroshahi, Kaveh Edalati, Masashige Hirayama, Hoda Emami, Makoto Arita, Miho Yamauchi, Hidehisa Hagiwara, Shintaro Ida, Tatsumi Ishihara, Etsuo Akiba, Zenji Horita, Masayoshi Fuji, Visible-Light-Driven Photocatalytic Hydrogen Generation on Nanosized TiO2-II Stabilized by High-Pressure Torsion, ACS Catalysis, 10.1021/acscatal.6b01482, 6, 8, 5103-5107, 2016.08, Photocatalytic activity of pure TiO2 is limited to ultraviolet (UV) light due to the wide bandgap of anatase and rutile phases. The bandgap of high-pressure phases of TiO2 can theoretically coincide with visible light, but these phases are unstable at ambient pressure. In this work, the high-pressure TiO2-II (columbite) phase with large fractions of oxygen vacancies was stabilized by inducing plastic strain to anatase under 6 GPa. The material could absorb visible light as a consequence of bandgap narrowing by â14 0.7 eV. Formation of nanosized TiO2-II enhanced the hydrogen generation efficiency under visible light, and the efficiency improved after removing the oxygen vacancies by annealing..
40. Miho Yamauchi, Masaaki Sadakiyo, Shotaro Yoshimaru, H. Kasai, K. Kato, M. Takata, A new approach for the facile preparation of metal-organic framework composites directly contactingwith metal particles through ark plasma deposition, Chem. Comm., 52, 8385-8388, 2016.05, A new approach for the facile preparation of metal-organic framework composites directly contactingwith metal particles through ark plasma deposition.
41. Sichao Ma, Masaaki Sadakiyo, Raymond Luo, Minako Heima, Miho Yamauchi, Paul J.A. Kenis, One-step electrosynthesis of ethylene and ethanol from CO2 in an alkaline electrolyzer, Journal of Power Sources, 10.1016/j.jpowsour.2015.09.124, 301, 219-228, 2016.01, Electroreduction of CO has potential for storing otherwise wasted intermittent renewable energy, while reducing emission of CO into the atmosphere. Identifying robust and efficient electrocatalysts and associated optimum operating conditions to produce hydrocarbons at high energetic efficiency (low overpotential) remains a challenge. In this study, four Cu nanoparticle catalysts of different morphology and composition (amount of surface oxide) are synthesized and their activities towards CO reduction are characterized in an alkaline electrolyzer. Use of catalysts with large surface roughness results in a combined Faradaic efficiency (46%) for the electroreduction of CO to ethylene and ethanol in combination with current densities of ∼200 mA cm , a 10-fold increase in performance achieved at much lower overpotential (only < 0.7 V) compared to prior work. Compared to prior work, the high production levels of ethylene and ethanol can be attributed mainly to the use of alkaline electrolyte to improve kinetics and the suppressed evolution of H , as well as the application of gas diffusion electrodes covered with active and rough Cu nanoparticles in the electrolyzer. These high performance levels and the gained fundamental understanding on Cu-based catalysts bring electrochemical reduction processes such as presented here closer to practical application. 2 2 2 2 2 -2.
42. Miho Yamauchi, Masaaki Sadakiyo, Preparation of solid–solution type Fe–Co nanoalloys by synchronous deposition of Fe andCo using dual arc plasma guns, Dalton Trans., 44, 11295-11298, 2015.05.
43. Miho Yamauchi, Takeshi Matsumoto, Masaaki Sadakiyo, Atomically Mixed Fe-Group Nanoalloys: Catalyst Design for the Selective Electrooxidation of Ethylene Glycol to Oxalic Acid, Phys. Chem. Chem. Phys., DOI: 10.1039/C5CP00954E, 17, 11395-11366, 2015.05.
44. Miho Yamauchi, Ryota Watanabe, Masaaki Sadakiyo, Ryu Abe, Tatsuya Takeguchi, CO2-free electric power circulation via direct charge and discharge using the glycolic acid/oxalic acid redox couple, Energy Environ. Sci., DOI: 10.1039/C5EE00192G, 8, 15764-15768, 2015.01.
45. Miho Yamauchi, Takeshi Matsumoto, Masaaki Sadakiyo, Sho Kitano, CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media, Scientific Reports, DOI:10.1038/srep05620, 5, 5620-5620, 2014.06.
46. Miho Yamauchi, Masaaki Sadakiyo, Synthesis and catalytic application of PVP-coated Ru nanoparticles embedded in a porous metal-organic framework, Dalton Trans., DOI: 10.1039/C4DT00996G, 43, 11295-11298, 2014.05.
47. Miho Yamauchi, Minako Heima, Masaaki Sadakiyo, Development of Nanoalloy Catalysts for Realization of Carbon-Neutral Energy Cycles, Mater. Sci. Forum., 10.4028/, 783-786, 2046-2050, 2014.03, Increase of CO2 concentration in the atmosphere is one of reasons for the global warming. Development of energy circulation systems, which do not emit CO2 in the atmosphere, is an emergent issue for present-generation scientists [1]. As an answer, we have proposed a new type of energy circulation system, namely, carbon-neutral energy (CN) cycle. With a practical application in mind, three limitations are imposed on the CN cycle; (1) no CO2 emissions, (2) utilization of liquid fuels and (3) minimizing the use of precious metal catalysts. In anticipation of a practical use in the near future, an alkaline fuel cell will be adapted for the CN cycle where non-platinum catalysts can work. For our purpose, electric power will be generated by partial oxidation of alcohols to carboxylic acids.[2] In view of ease in handling, fuels having a high boiling point (b.p.) are favorable for the CN cycles. To this end, glycol (EG) of which b.p. is 470 K an ideal candidate as a fuel. In this case, an oxidized product of EG can be oxalic acid. Compared to the energy obtained by the complete oxidation of EG into CO2, we can derive ca. 80 % of energy even in the partial oxidation of EG to oxalic acid, implying that the EG/oxalic cycle possibly works as an energy cycle. We herein show an example of selective EG oxidation catalysts working in alkaline conditions.
In the previous reports, Pd-based catalysts are found to show remarkably high activities for alcohol oxidation in the alkaline media.[3,4] In this study, Cu-Pd nanoalloy catalysts are synthesized and applied to the EG electrooxidation in the alkaline conditions..
48. Miho Yamauchi, Hydrogen-related Properties of Metal and Alloy Nanoparticles,, 2, 010305-010305, 2014.03, Transition metals exhibit strong interaction with hydrogen regardless of their chemical form. Metal particles in the nanometer range, i.e., metal nanoparticles (NPs), have unique properties, which are different from those of their bulk counterparts, resulting from their large surface fractions and specific electronic states, depending on the particle size. It is natural, therefore, that hydrogen storage properties vary depending on the metal size. In this paper, I discuss nano-size effects on hydrogen storage in metal NPs by taking an example of Pd NPs, which bulk store hydrogen in their lattices, using Pd NPs as an example[1]
The other target materials in our study are bimetallic nanoalloys (NAs), which have great potential as novel catalysts because their reactivities can be controlled by changing the composition and elemental distributions in the particles. Considering the electronegativity of hydrogen, 2.2, which is close to those of the late transition metals, 1.8—2.6, various transition-metal NAs are expected to show significant affinities to hydrogen through a moderate metallic bonds; this probably influences the metal structure. In our study, hydrogen treatment was used to change the structures of NAs. Recently, we observed hydrogen-enhanced ordering of the CuPd NAs.[2] Here, I review our works on hydrogen-related properties of metal and alloy NPs..
49. Miho Yamauchi, Masaaki Sadakiyo, Design and synthesis of hydroxide ion-conductive metal-organic frameworks based on salt inclusion, J. Am. Chem. Soc., 10.1021/ja410368j, 136, 5, 1702-1705, 2014.01, We demonstrate a metal–organic framework (MOF) design for the inclusion of hydroxide ions. Salt inclusion method was applied to an alkaline-stable ZIF-8 (ZIF: zeolitic imidazolate framework) to introduce alkylammonium hydroxides as ionic carriers. We found that tetrabutylammonium salts are immobilized inside the pores by a hydrophobic interaction between the alkyl groups of the salt and the framework, which significantly increases the hydrophilicity of the ZIF-8. Furthermore, the ZIF-8 including the salt exhibited a capacity for OH– ion exchange, implying that freely exchangeable OH– ions are present in the MOF. The ZIF-8 containing OH– ions showed an ionic conductivity of 2.3 × 10–8 S cm–1 at 25 °C, which is four orders of magnitude higher than that of the blank ZIF-8. This is the first example of an MOF-based hydroxide ion conductor..
50. Md Jafar Sharif, Miho Yamauchi, Shoichi Toh, Syo Matsumura, Shin-ichiro Noro, Kenichi Kato, Masaki Takata, Tatsuya Tsukuda, Enhanced Magnetization in Highly-Crystalline and Atomically-Mixed bcc Fe-Co Nanoalloys Prepared by Hydrogen Reduction of Oxide Composites, Nanoscale,, 5, 1489-1493, 2013.03.
51. Atsunori Kamegawa, Asaya Fujita, Miho Yamauchi, Masuo Okada, New useful function of hydrogen in materials, J. Alloys Compd., 10.1016/j.jallcom.2013.03.225, 580, S401-S405, 2013.01.
52. K. Kusada, M. Yamauchi, H. Kobayashi, H. Kitagawa, Y. Kubota, Hydrogen-Storage Properties of Solid-Solution Alloys of Immiscible Neighboring Elements with Pd, J. Am. Chem. Soc., 132, 15896-15898, 2012.06.
53. Kobayashi, Hirokazu, Morita, Hitoshi, Miho Yamauchi, Ikeda, Ryuichi, Kitagawa, Hiroshi, Kubota, Yoshiki, Kato, Kenichi, Takata, Masaki, Toh, Shoichi, Matsumura, Syo, Nanosize-Induced Drastic Drop in Equilibrium Hydrogen Pressure for Hydride Formation and Structural Stabilization in Pd-Rh Solid-Solution Alloys, 134, 12390-12393, 2012.06.
54. M. Prasenjit, X. Songhai, H. Tsunoyama, Miho Yamauchi, T. Tsukuda, Stabilized gold clusters: from isolation toward controlled synthesis, Nanoscale,, 4, 4027-4037, 2012.05.
55. H. Kobayashi, Miho Yamauchi, H. Kitagawa, Finding Hydrogen-Storage Capability in Iridium Induced by the Nanosize Effect, J. Am. Chem. Soc.,, 134, 6893-6895, 2012.04.
56. P. Maity, T. Wakabayashi, N. Ichikuni, H. Tsunoyama, S. Xie, Miho Yamauchi, T. Tsukuda, Selective synthesis of organogold magic clusters Au54(C≡CPh)26, Chem. Comm., 48, 6085-6087, 2012.02.
57. M. Prasenjit, H. Tsunoyama, M. Yamauchi, X. Songhai, T. Tsukuda, Organogold Clusters Protected by Phenylacetylene, J. Am. Chem. Soc., 134, 20123-20125, 2012.01.
58. Hirokazu Kobayashi, Hitoshi Morita, Miho Yamauchi, Ryuichi Ikeda, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, Masaki Takata, Nanosize-induced hydrogen storage and capacity control in a non-hydride-forming element: Rhodium, Journal of the American Chemical Society, 10.1021/ja2027772, 133, 29, 11034-11037, 2011.07, We report the first example of nanosize-induced hydrogen storage in a metal that does not absorb hydrogen in its bulk form. Rhodium particles with diameters of <10 nm were found to exhibit hydrogen-storage capability, while bulk Rh does not absorb hydrogen. Hydrogen storage was confirmed by in situ powder X-ray diffraction, solid-state H NMR, and hydrogen pressure - composition isotherm measurements. The hydrogen absorption capacity could be tuned by controlling the particle size. © 2011 American Chemical Society. 2.
59. M. Yamauchi, R. Abe, T. Tsukuda, K. Kato and M. Takata, Highly Selective Ammonia Synthesis from Nitrate with Photocatalytically Generated Hydrogen on CuPd/TiO2, J. Am. Chem. Soc., 133, 1150–1152, 2011.01.
60. M. Yamauchi, T. Tsukuda, Production of Ordered (B2) CuPd Nanoalloy by Low–Temperature Annealing under Hydrogen Atmosphere, Dalton Trans, 2011.01.
61. T. Takeguchi, H. Arikawa, M. Yamauchi, and R. Abe, Selective Ethylene Glycol Oxidation Reaction for Carbon Neutral Energy Cycle System, ECS Transactions, 41, 1755-1759, 2011.01.
62. M. Okada, A. Kamegawa, J. Nakahigashi, A. Yamaguchi, A. Fujita, M. Yamauchi, New function of hydrogen in materials, Mater. Sci. Eng. B,, 173, 253-259, 2010.01.
63. H. Kobayashi, M. Yamauchi, H. Kitagawa, Y. Kubota, K. Kato, M. Takata, Atomic Level Pd-Pt alloying and Largely Enhanced Hydrogen-Storage Capacity in Bimetallic Nanoparticles Reconstructed from Core/Shell Structure by a Process of Hydrogen Absorption/Desorption, J. Am. Chem. Soc., 132, 5576–5577, 2010.01.
64. M. Yamauchi, K. Kobayashi, H. Kitagawa, Hydrogen storage mediated by Pd and Pt nanoparticles, ChemPhysChem, 10, 2566–2576, 2009.01.
65. R. Makiura, T. Yonemura, T. Yamada, M. Yamauchi, R. Ikeda, H. Kitagawa, K. Kato, M. Takata, Size-controlled stabilization of the superionic phase to room temperature in polymer-coated AgI nanoparticles, Nature Materials, 8, 476–480, 2009.01.
66. K. Kobayashi, M. Yamauchi, R. Ikeda, H. Kitagawa, Atomic-Level Pd-Au Alloying and Controllable Hydrogen-Absorption Properties in Size-Controlled Nanoparticles Synthesized by Hydrogen Reduction Method, Chem. Commun., 4806–4808, 2009.01.
67. Hirokazu Kobayashi, Miho Yamauchi, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, Takata Masaki, On the Nature of Storng Hydrogen Trapping Inside Pd Nanoparticles, Journal of the American Chemical Society, 130巻6号1828-1829, 2008.05.
68. Miho Yamauchi, Ryuichi Ikeda, Hiroshi Kitagawa, and Masaki Takata, Nanosize Effects on Hydrogen Storage in Palladium, The Journal of Physical Chemistry C, 112巻9号:3294-3299, 2008.05.
69. M. Nakaya, M. Kanehara, M. Yamauchi, H. Kitagawa, T. Teranishi, Hydrogen-Induced Crystal Structural Transformation of FePt Nanoparticles at Low Temperature, J. Phys. Chem C,, 111, 20, 7231-7234, 111, 7231-7234 (2007), 2007.05.
70. M. Yamauchi and H. Kitagawa, Hydrogen Absorption of the Polymer-coated Pd Nanoparticle, Synth. Metals, 10.1016/j.synthmet.2005.07.296, 153, 1-3, 353-356, 153, 353-356 (2005), 2005.09.
71. M.Fujishima, M. Yamauchi, R. Ikeda, T. Kubo, K. Nakasuji andH. Kitagawa, Powder XRD and Solid-State 2H NMR Studies on RAP-Protected Palladium Nanoparticle (RAP=Rubeanic-Acid Polymer), Solid State Phenom, 10.4028/3-908451-18-3.107, 111, 107-110, 111, 107-110 , (2006), 2005.07.
72. M. Yamauchi, H. Kitagawa, Hydrogen Absorption in Size-Controlled Pt Nanoparticle, Chemical Engineering Transactions, 8, 159-163, 8, 159-163 (2005), 2005.05, [URL].
73. T. Ishimoto, M. Tachikawa, M. Yamauchi, H. Kitagawa, H. Tokiwa, U. Nagashima, Isotope effect in hydrogen/deuterium-absorbing Pd nanoparticles revealed by X-ray powder diffraction and by a multi-component MO method, J. Phys. Soc. Jpn,, 73(7), 1775-1780 (2004), 2004.10.
74. Yamauchi, Miho; Takazaki, Yasuaki; Yang, Zhiyong; Kawamura, Takashi; Ikeda, Ryuichi, A 1H NMR study on the electronic state of a chloride-bridged tetrakis(acetamidato)dirhodium complex, Chem. Lett., 33(2), 110-111, 2004.01.
75. M. Yamauchi, S. Ishimaru, and R. Ikeda, Dynamics of n-alkylammonium ions intercalated in saponite, Journal of Physical Chemistry A, 76(12), 2301-2305, 2004.01.
76. T. Ishimoto, M. Tachikawa, M. Yamauchi, H. Kitagawa, H. Tokiwa, and U. Nagashima, Isotope Effect of Hydrogen-Absorbing Pd Ultrafine Particle -X-ray Powder Diffraction and Multi-Component MO Method-, Chem. Phys. Lett., 372(3,4), 503-507, 2003.01.
77. S. Ishimaru, M. Yamauchi, and R. Ikeda, A New Semiconducting Organic-Inorganic Nanocomposite, 1,5-Diaminonphthalene-Saponite Intercalation Compound, Solid State Commun, 127(1), 57-59, 2003.01.
78. Shinohara, Emi; Yamauchi, Miho; Ishimaru, Shin'ichi; Ikeda, Ryuichi, Two-Dimensional Self-Diffusion of Alkylammonium Ions Located in the Interlayer Space of Tetrasilicicfluormica, Journal of Physics: Condensed Matter, 10.1021/jp035874x, 108, 5, 717-720, 108(5), 717-720, 2003.01.
79. M. Yamauchi , Y. Isobe, R. Ikeda, H. Kitagawa, T. Teranishi, and M. Miyake, A Study on Hydrogen Adsorption of Polymer Protected Pt nanoparticles, Synthetic Metals, 135-136, 757-758, 2003.01.
80. M. Yamauchi, A. B. Koudriavtsev, R. Ikeda, Z. Yang, and T. Kawamura, Spin Polarization in Infinite Zigzag Chains of [Rh2(HNCOCH3)4Cl]n, Mol. Cryst. Liq. Cryst.,, 379, 321-326, 379, 321-326, 2002.01.
81. M. Yamauchi, S. Ishimaru, and R. Ikeda, Dynamics of n-Octylammonium Ions Intercalated in Saponite, Mol. Cryst. Liq. Cryst.,, 341, 315-320, 2000.01.
82. S. Ishimaru, M. Yamauchi, and R. Ikeda, Dynamics of Interlayer Cations in Tetramethylammonium-Saponite Studied by 1H, 2H NMR, and Electrical Conductivity Measurements, Z. Naturforsch., 53a, 903-908 (1998)., 1998.01.
83. M. Yamauchi, S. Ishimaru, and R. Ikeda, Dynamics of Two-Dimensionally Arranged n-Octylammonium Ions Intercalated into Tetrasilicicfluormica, Z. Naturforsch, 54a, 755-760, 1998.01.