Faculty Profiles - HIBINO, Takashi

Papers - HIBINO, Takashi

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Proton conduction in non-doped and acceptor-doped metal pyrophosphate (MP2O7) composite ceramics at intermediate temperatures Reviewed

Sato Yousuke, Shen Yanbai, Nishida Masakazu, Kanematsu Wataru, Hibino Takashi

JOURNAL OF MATERIALS CHEMISTRY Vol. 22 ( 9 ) page： 3973 - 3981 2012

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Materials Chemistry

Proton conductors capable of operating in the temperature range of 100-600°C have received great interest for many application areas such as fuel cells, sensors, and electrolyzers; however, very few materials that can satisfy these demands have been reported to date. Here, we report a promising candidate for a solid electrolyte in intermediate-temperature electrochemical devices. First, MP 2O 7-MO 2 composite ceramics (M = Sn, Si, Ti, and Zr) were prepared by reacting a porous MO 2 substrate with an 85% H 3PO 4 solution at 600°C. Although all the tested MO 2 could react with H 3PO 4 to form the corresponding metal pyrophosphate layers on the surfaces of the exterior and interior substrate, the extent of MP 2O 7 growth in the obtained samples and their relative density were strongly dependent on the M species. These factors were the best for the SnP 2O 7-SnO 2 composite ceramic, yielding the highest electrical conductivity in the temperature range of interest. Next, different low valence cations (cation = Mg 2+, Sc 3+, Ga 3+, Y 3+, In 3+, La 3+, Sm 3+, Eu 3+, and Gd 3+) were doped into the SnP 2O 7-SnO 2 composite ceramic. The most positive effect on the electrical conductivity was observed when Sm 3+ was used as the dopant; the electrical conductivity of this sample was approximately one order of magnitude higher than that of the non-doped sample, especially at low temperatures below 250°C. Fourier transform infrared (FTIR) and proton magic angle spinning (MAS) nuclear magnetic resonance (NMR) analyses revealed that the quantity of protons incorporated in the SnP 2O 7 layer and their mobility were increased by the doping of Sm into the composite ceramic. As a consequence, the electrical conductivity of the Sm-doped SnP 2O 7-SnO 2 composite ceramic reached ∼10 -2 S cm -1 in the temperature range of 100-600°C. Proton conduction in this sample was also investigated by various electrochemical techniques. The protons function as the predominant charge carrier in the sample, and the proton transport number was almost unity in both static and dynamic conditions. © 2012 The Royal Society of Chemistry.

DOI： 10.1039/c2jm15335a

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総説：ナノ局所電池デバイスのエネルギー・環境技術への応用

日比野高士

ケミカルエンジニヤリング Vol. 56 ( 10 ) page： 48-54 2011.10

Intermediate-temperature proton conductors and their applications to energy and environmental devices Reviewed Open Access

Hibino Takashi

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN Vol. 119 ( 1393 ) page： 677 - 686 2011.9

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of the Ceramic Society of Japan

The development of proton conductors has proceeded rapidly in recent years. A number of organic or inorganic materials show proton conductivities of ∼10-2Scm-1 at temperatures below 100°C. However, although there is great current demand for proton conductors capable of operating in the temperature range of 100400° C in practical applications, very few materials that can satisfy this demand have been reported to date. Acceptor-doped SnP2O7 are promising candidate materials because their proton conductivities reach >10-1Scm-1 in the temperature range of interest. This paper presents an overview of the current status of acceptor-doped SnP2O7, highlighting the mechanism and kinetics of proton conduction and the development of electrochemical devices using these materials. New insights for proton insertion and conduction are proposed that use electrochemical techniques. Two approaches to designing SnP2O7-based composite electrolytes with good mechanical properties have also been developed for different operating temperatures. In addition, the benefits of intermediate-temperature operation using these materials are discussed in terms of practical applications, especially in fuel cells, exhaust sensors, and solid catalysts. © 2011 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.119.677

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Ultra-low loading Pt Rh/Sn0.9In0.1P2O7 three-way catalyst for propane + NO + O-2 reaction Reviewed

Dong Xue, Tsuneyama Kota, Hibino Takashi

APPLIED CATALYSIS B-ENVIRONMENTAL Vol. 106 ( 3-4 ) page： 503 - 509 2011.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Applied Catalysis B: Environmental

Propane oxidation and NO reduction at the proton conductor-electrocatalyst interface were investigated using electrochemical cells and impregnated catalysts. Sn0.9In0.1P2O7 and Pt or Pt-Rh were used as the proton conductor and electrocatalyst, respectively. In a gaseous mixture of propane, H2O, and NO, H2O is dissociated into protons and electrons at anodic sites at the interface and the resultant active oxygen oxidizes propane to CO2. Separately, NO reacts with protons and electrons to form N2O at cathodic sites at the interface. Under stoichiometric conditions, including 1000ppm propane, 1000ppm NO, 3% H2O, and 4500ppm O2, the temperatures at which the above series of reactions could successfully achieve 50% conversion (T50%) was reduced to 310 and 385°C for propane and NO, respectively, over a 0.01wt.% Pt/Sn0.9In0.1P2O7 catalyst. These were much lower than T50% of 430 and 535°C for propane and NO, respectively, over a 0.01wt.% Pt/γ-Al2O3 catalyst. Moreover, the addition of 0.005wt.% Rh to the Pt/Sn0.9In0.1P2O7 catalyst enhanced NO reduction by promoting the dissociative adsorption of NO, thus providing a further reduction of T50% for the NO reaction to 355°C. © 2011 Elsevier B.V.

DOI： 10.1016/j.apcatb.2011.06.009

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An H3PO4-doped polybenzimidazole/Sn0.95Al0.05P2O7 composite membrane for high-temperature proton exchange membrane fuel cells Reviewed

Jin Y. C., Nishida M., Kanematsu W., Hibino T.

JOURNAL OF POWER SOURCES Vol. 196 ( 15 ) page： 6042 - 6047 2011.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Power Sources

A polybenzimidazole (PBI)/Sn0.95Al0.05P 2O7 (SAPO) composite membrane was synthesized by an in situ reaction of SnO2 and Al(OH)3-mixed powders with an H3PO4 solution in a PBI membrane. The formation of a single phase of SAPO in the PBI membrane was completed at a temperature of 250 °C. Thermogravimetric analysis showed that the PBI membrane was not subject to a serious damage by the presence of SAPO until 500 °C. Scanning electron microscopy revealed that SAPO particles with a diameter of approximately 300 nm were homogeneously dispersed and separated from each other in the PBI matrix. Proton magic angle spinning nuclear magnetic resonance spectra confirmed the presence of new protons originating from the SAPO particles in the composite membrane. As a consequence of the interaction of protons in the SAPO with those in the free H3PO4, the H3PO4-doped PBI/SAPO composite membrane exhibited conductivities several times higher than those of an H3PO4-doped PBI membrane at room temperature to 300 °C, which could contribute to the improved performance of H 2/O2 fuel cells. © 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jpowsour.2011.03.094

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A comparative study of Pt/C cathodes in Sn0.9In0.1P2O7 and H3PO4 ionomers for high-temperature proton exchange membrane fuel cells Reviewed

Jin Y. C., Okada M., Hibino T.

JOURNAL OF POWER SOURCES Vol. 196 ( 11 ) page： 4905 - 4910 2011.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Power Sources

New Pt/C cathodes with many reaction sites for the oxygen reduction reaction as well as high tolerance to Pt corrosion have been designed for high-temperature proton exchange membrane fuel cells (PEMFCs), wherein a composite mixture of Sn0.9In0.1P2O7 (SIPO) and sulfonated polystyrene-b-poly(ethylene/butylene)-b-polystyrene (sSEBS) functioned as an ionomer. The microstructure of the Pt-SIPO-sSEBS/C cathode was characterized by homogeneous distribution of the ionomer over the catalyst layer and close contact between the ionomer and the Pt/C powder. As a result, the activation and concentration overpotentials of the Pt-SIPO-sSEBS/C cathode between 100 and 200 °C were lower than those of an H 3PO4-impregnated Pt/C cathode, which suggests that the present ionomer can avoid poisoning of Pt by phosphate anions and the limitation of gas diffusion through the catalyst layer. Moreover, agglomeration of Pt in the Pt-SIPO-sSEBS/C cathode was not observed during a durability test at 150 °C for 6 days, although it was significant in the Pt-H3PO 4/C cathode. Therefore, it is concluded that the Pt-SIPO-sSEBS/C electrode is a very promising cathode candidate for high-temperature PEMFCs. © 2011 Elsevier B.V.

DOI： 10.1016/j.jpowsour.2011.02.028

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Efficient and selective formation of methanol from methane in a fuel cell-type reactor Reviewed

Lee Byungik, Hibino Takashi

JOURNAL OF CATALYSIS Vol. 279 ( 2 ) page： 233 - 240 2011.4

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Catalysis

Direct oxidation of methane to methanol at low temperatures was investigated using a fuel cell-type reactor, where a mixture of methane and H2O vapor was supplied to the anode and air to the cathode. Methanol was scarcely produced over a Pt/C anode from 50 to 250 °C. However, through trial and error, the production of methanol over a V2O 5/SnO2 anode was significant at 100 °C; the current efficiency for methanol production and the selectivity toward methanol were as high as 61.4% and 88.4%, respectively. Methanol was produced by the reaction of methane with an active oxygen species over the V2O5 catalyst. Cyclic voltammetry of the anode indicated that the generation of such active oxygen species was strongly dependent on the anode potential. Moreover, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements confirmed that highly dispersed and partially reduced vanadium species were present on the SnO2 surface. These vanadium species are considered to be active sites for the formation of the active oxygen species, probably anion radicals (O2·- and O·-). © 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2010.12.020

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Efficient and selective formation of methanol from methane in a fuel cell type reactor Reviewed

Byungik Lee, Takashi Hibino

Journal of Catalysis Vol. 279 page： 233-240 2011.4

総説：ナノ分極型高選択反応性電極の創製

日比野高士

Electrochemistry Vol. 79 ( 4 ) page： 274-279 2011.4

Design of a highly sensitive and responsive electrode for particulate matter monitoring Reviewed

Shen Y. B., Takeuchi T., Hibino T.

SENSORS AND ACTUATORS B-CHEMICAL Vol. 153 ( 1 ) page： 226 - 231 2011.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical

In a previous sensor device based on a PtSn0.9In 0.1P2O7Pt electrode system, electrochemical carbon oxidation was realized over the surface of a working electrode, enabling continuous carbon monitoring with self-regeneration of the sensor. Specific reactivity of the active oxygen species for carbon was demonstrated along with a high current efficiency. However, this reaction did not occur over the entire electrode layer, limiting the sensing properties and giving a low sensitivity and response speed. The main reason for carbon oxidation being limited to the surface region was the lack of proton conduction in the working electrode. To overcome this problem, we added proton-conducting Sn0.9In 0.1P2O7 particles as an ionomer to the working electrode. The Sn0.9In0.1P2O7 ionomer was successfully distributed over the working electrode at the level of a few micrometers, providing reaction sites for carbon oxidation over the entire electrode layer. The resulting amperometric sensor provided a sensitivity to carbon that was 1.4 times greater than that of the ionomer-free working electrode, as determined by the current at which carbon oxidation had ceased. Moreover, carbon floating in a glass container could be transported to reaction sites present on the external surface of the working electrode, allowing for a large current and a rapid response. © 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2010.10.042

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Design of a highly sensitive and responsive electrode for monitoring diesel particulate matter Reviewed

Yanbai Shen, Takashi Takeuchi, Takashi Hibino

Sensors and Actuators B: Chemical Vol. 153 page： 226-231 2011.3

Synthesis and characterization of dense SnP2O7-SnO2 composite ceramics as intermediate-temperature proton conductors Reviewed

Yanbai Shen, Masakazu Nishida, Wataru Kanematsu, Takashi Hibino

Journal of Materials Chemistry Vol. 21 page： 663-670 2011.1

Compact bipolar plate-free direct methanol fuel cell stacks Reviewed

Dong Xue, Takahashi Motohiro, Nagao Masahiro, Hibino Takashi

CHEMICAL COMMUNICATIONS Vol. 47 ( 18 ) page： 5292 - 5294 2011

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Chemical Communications

Fuel cells with a PtAu/C anode and a Pr-doped Mn2O3/C cathode were stacked without using a bipolar plate, and their discharge properties were investigated in a methanol aqueous solution bubbled with air. A three-cell stack exhibited a stack voltage of 2330 mV and a power output of 21 mW. © The Royal Society of Chemistry 2011.

DOI： 10.1039/c1cc10493d

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Synthesis and characterization of dense SnP2O7-SnO2 composite ceramics as intermediate-temperature proton conductors Reviewed

Shen Yanbai, Nishida Masakazu, Kanematsu Wataru, Hibino Takashi

JOURNAL OF MATERIALS CHEMISTRY Vol. 21 ( 3 ) page： 663 - 670 2011

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Materials Chemistry

Dense SnP2O7-SnO2 composite ceramics were prepared by reacting a porous SnO2 substrate with an 85% H3PO4 solution at elevated temperatures. At 300 °C and higher, SnO2 reacted with H3PO4 to form an SnP2O7 layer on exterior and interior surfaces in the substrate, the growth rate of which increased with increasing reaction temperature. Finally, at 600 °C, the pores of this composite ceramic were perfectly closed and its electrical conductivity became several orders of magnitude higher than that of the SnO2 substrate alone. Proton conduction was demonstrated in this composite ceramic using electrochemical measurements and various analytical techniques. Comparison of the observed electromotive force with the theoretical value in two gas concentration cells demonstrated that this composite ceramic is a pure ion conductor, wherein the predominant ion species are protons. Fourier transform infrared (FT-IR) and proton magic angle spinning (MAS) nuclear magnetic resonance (NMR) analyses revealed that the protons interacted with lattice oxide ions in the SnP2O7 layer to form hydrogen bonds. An H/D isotope effect suggested that proton conduction in this composite ceramic was based on a proton-hopping mechanism. The proton conductivity in this material reached ∼10-2 S cm-1 in the temperature range of 250-600 °C. © The Royal Society of Chemistry.

DOI： 10.1039/c0jm02596h

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A proton-conducting composite membrane Sn0 95Al0 05P2O7 and polystyrene-b-poly(ethylene/propylene)-b-polystyrene Reviewed

Jin Yongcheng, Hibino Takashi

ELECTROCHIMICA ACTA Vol. 55 ( 28 ) page： 8371 - 8375 2010.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochimica Acta

An anhydrous proton conductor, Sn0.95Al0.05P 2O7 (SAPO), composed of polystyrene-b-poly(ethylene/ propylene)-b-polystyrene (SEPS), was developed and characterized using morphological, structural, and electrochemical analyses. In the composite membrane with 20 wt% SEPS, a homogeneous distribution of SAPO particles in the matrix was obtained in the thickness range of 65-90 μm, yielding a proton conductivity of 3.4 × 10-3 S cm-1 at 200 °C, tensile strength of 4.6 MPa and an elongation at break of 711.0% at room temperature. Fuel cell tests verified that the open-circuit voltage was maintained at a constant value of approximately 1 V between 100 and 250 °C. The peak power densities achieved with unhumidified H2 and air were 77.0 mW cm-2 at 100 °C, 121.0 mW cm-2 at 150 °C, and 163.1 mW cm-2 at 225 °C. © 2010 Elsevier Ltd All rights reserved.

DOI： 10.1016/j.electacta.2010.07.043

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A proton-conducting composite membrane: Sn0.95Al0.05P2O7 and polystyrene-b-poly(ethylene/propylene)-b-polystyrene Reviewed

Yongcheng Jin, Takashi Hibino

Electrochimica Acta Vol. 55 page： 8371-8375 2010.12

Separator-free fuel cell stacks operating in a mixture of hydrogen and air Reviewed

Masahiro Nagao, Motohiro Takahashi, Takashi Hibino

Energy & Environmental Science Vol. 3 page： 1934-1940 2010.12

Separator-free fuel cell stacks operating in a mixture of hydrogen and air Reviewed

Nagao Masahiro, Takahashi Motohiro, Hibino Takashi

ENERGY & ENVIRONMENTAL SCIENCE Vol. 3 ( 12 ) page： 1934 - 1940 2010.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Energy and Environmental Science

Fuel cells for vehicular and residential applications have encountered a key technical challenge in cost reduction. This challenge can be avoided by operating a fuel cell stack without the use of gas separators, which are expensive and voluminous and therefore comprise a significant portion of the cost of a fuel cell stack. Single-chamber fuel cells (SCFCs) have the potential of realizing such operation, because there is no need for separation between fuel and air. In this paper, we present a selective anode (PtAu/C) and cathode (Pr-doped Mn2O3/C) for respective electrochemical hydrogen oxidation and oxygen reduction reactions in a SCFC. A single cell with these electrodes operated at 50 °C generated an open-circuit voltage of 1204 mV and a peak power density of 50 mW cm-2 in a feed mixture of 80% hydrogen and 20% air at a flow rate of 30 mL min-1. The high selectivity of these electrodes also enabled the design of two different separator-free fuel cell stacks, parallel and perpendicular to the gas stream. Both cell stacks exhibited increasing stack voltage and power output almost proportionally to the increase in the number of single cells. These results demonstrate that the separator-free fuel cell stack shows high potential for a significant reduction of the cost of fuel cell systems. © The Royal Society of Chemistry.

DOI： 10.1039/c0ee00288g

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Partially proton-exchanged WP2O7 with high conductivity at intermediate temperatures Reviewed

Yongcheng Jin, Lu Yang, Masakazu Nishida, Wataru Kanematsu, Takashi Hibino

Electrochemical and Solid-State Letters Vol. 13 ( 11 ) page： B123-B126 2010.11

Development and application of SnP<inf>2</inf>O<inf>7</inf>-based proton conductors to intermediate-temperature fuel cells Reviewed Open Access

Jin Y., Lee B., Hibino T.

Journal of the Japan Petroleum Institute Vol. 53 ( 1 ) page： 12 - 23 2010.10

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of the Japan Petroleum Institute

Much attention has been devoted to efforts to operate polymer electrolyte fuel cells (PEFCs) at temperatures above 100°C in order to avoid the problem of serious CO poisoning of the anode catalyst. It is also of great con cern to operate PEFCs under low-humidity conditions, because the space and energy required for external humidi fication are eliminated or minimized in the fuel cell system. Thus, proton-conducting materials that can satisfy the above criteria have been proposed, developed, and evaluated worldwide. In particular, recent research efforts have been increasingly focusing on the design of anhydrous proton conductors, since these materials, at least in principle, do not need the presence of water as a charge carrier. We have recently found that In, Al, or Mg-doped SnP2O7 show high proton conductivities>10-1 S. cm-1 between 150 and 350 °C under water-free conditions. Attempts to apply these materials as electrolytes in some electrochemical devices were also made. This paper presents an overview of the current status of doped SnP22O 7 with principal emphasis on the materials aspect. In addition, the benefits of intermediate-temperature fuel cells using these materials are briefy summarized in terms of cell design, electrolyte and electrode materials.

DOI： 10.1627/jpi.53.12

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Papers - HIBINO, Takashi