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Miho Yamauchi Last modified date:2022.01.14

Graduate School

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Academic Degree
Ph. D
Field of Specialization
Solid-state physical chemistry, Solid-state NMR, Nano materials, Catalysis, Hydrogen storage
Outline Activities
We are developing novel nanometer-sized materials for highly efficient material/energy conversions.
Research Interests
  • Development of highly selective nanoalloy catalysts for realization of carbon neutral energy cycles
    keyword : carbon neutral, catalysis, nanoalloys, hydrogen, ethylene glycol, ammonia
    2012.01Size dependencies of hydrogen storage in Pd nanoparticles.
Academic Activities
1. 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.
2. 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.
3. 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.
4. 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..
5. 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..
6. 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.
7. 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..
8. 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..
9. 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%..
10. 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..
11. 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.
12. 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..
13. 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..
14. 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..
15. 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.
16. 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.
17. 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..
18. 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.
19. 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.
20. 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.
21. 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.
22. 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.
23. 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.
24. 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..
25. 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..
26. 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..
27. 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.
28. 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.
29. M. Prasenjit, X. Songhai, H. Tsunoyama, Miho Yamauchi, T. Tsukuda, Stabilized gold clusters: from isolation toward controlled synthesis, Nanoscale,, 4, 4027-4037, 2012.05.
30. 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.
31. 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.
32. 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.
33. M. Yamauchi, T. Tsukuda, Production of Ordered (B2) CuPd Nanoalloy by Low–Temperature Annealing under Hydrogen Atmosphere, Dalton Trans, 2011.01.
34. M. Yamauchi, K. Kobayashi, H. Kitagawa, Hydrogen storage mediated by Pd and Pt nanoparticles, ChemPhysChem, 10, 2566–2576, 2009.01.
35. 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.
36. 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.
37. 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.
38. M. Yamauchi, H. Kitagawa, Hydrogen Absorption in Size-Controlled Pt Nanoparticle, Chemical Engineering Transactions, 8, 159-163, 8, 159-163 (2005), 2005.05, [URL].
39. 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.
40. 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.