Faculty Profiles - HIBINO, Takashi

Papers - HIBINO, Takashi

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Blocking of electronic current through a Ce0.9Gd0.1O1.95 electrolyte film by growth of a thin BaCe1-xGdxO3-alpha layer Reviewed

Tomita Atsuko, Tachi Yuki, Hibino Takashi

ELECTROCHEMICAL AND SOLID STATE LETTERS Vol. 11 ( 5 ) page： B68 - B70 2008

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemical and Solid-State Letters

A BaCe1-x Gdx O3-α (BCG) layer was grown between Ce0.9 Gd0.1 O1.95 (GDC) layers. This was accomplished by a solid-state reaction of a BaO layer with the GDC layer. In the multilayered GDC/BCG/GDC electrolyte film, all layers showed dense and homogeneous junction structure. When a hydrogen-air fuel cell with the multilayered electrolyte cell was tested at 550-800°C, the BCG layer could partially block the electronic current through the cell. The resulting open-circuit voltage and power density were increased by a maximum of 127 mV and 202 mW cm-2, respectively, compared with those for a single-layered GDC electrolyte cell under the same conditions. © 2008 The Electrochemical Society.

DOI： 10.1149/1.2865507

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A single-chamber SOFC stack operating in engine exhaust Reviewed

Yano Masaya, Nagaoa Masahiro, Okamoto Kohsuke, Inoa Atsuko Tomitab, Uchiyarna Yasuyuki, Uchiyama Naoki, Hibino Takashi

ELECTROCHEMICAL AND SOLID STATE LETTERS Vol. 11 ( 3 ) page： B29 - B33 2008

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemical and Solid-State Letters

Heat engines emit huge amounts of exhaust which contain considerable quantities of heat and chemical energies. An increasing public awareness of global warming and oil depletion has required the development of innovative methods of recovering energy from such exhaust. A promising approach is to produce electricity from unburned fuel by using a fuel cell system. The exhaust includes cracked-light hydrocarbons, offering the possibility of applying this system to a power generator. Solid oxide fuel cells (SOFCs) can work at elevated temperatures but have poor thermal and mechanical shock resistance. In this study, we address this problem by operating the fuel cell system in a single-chamber mode, wherein no separation between fuel and oxidant gases is required. This operation provides high tolerance toward thermal cycling and breakage of the electrolyte. As a result, a twelve-cell stack exhibits stable and high performance in the exhaust from a motorcycle. © 2007 The Electrochemical Society.

DOI： 10.1149/1.2824502

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Nano-sized electrochemical reactors for selective NOx reduction Reviewed

Teranishi Shinya, Tsuge Akihito, Tomita Atsuko, Sano Mitsuru, Hibino Takashi

ELECTROCHEMICAL AND SOLID STATE LETTERS Vol. 11 ( 10 ) page： P9 - P12 2008

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemical and Solid-State Letters

The present study proposed a scheme for the reaction between NOx and C3 H6 in the presence of excess O2 over a proton-conducting Sn0.9 In0.1 P2 O7 -supported PtRh catalyst. C3 H6 dissociated to protons and electrons at an anodic site of the PtRh catalyst, causing a negative potential. NOx reacted with protons and electrons to form N2 and H2 O at a cathodic site of the PtRh catalyst, resulting in a positive potential. As a result, an electrochemical local cell was formed at the PtRh Sn0.9 In0.1 P2 O7, followed by self-discharge. This series of reactions could be clearly distinguished from conventional catalytic reduction of NOx by C3 H6. © 2008 The Electrochemical Society. All rights reserved.

DOI： 10.1149/1.2966293

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Proton conduction in Sn(0.95)Al(0.05)P(2)O(7)-PBI-PTFE composite membrane Reviewed

Heo Pilwon, Kajiyama Norikazu, Kobayashi Kazuyo, Nagao Masahiro, Sano Mitsuru, Hibino Takashi

ELECTROCHEMICAL AND SOLID STATE LETTERS Vol. 11 ( 6 ) page： B91 - B95 2008

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemical and Solid-State Letters

Proton-conducting composite membranes were fabricated by blending Sn0.95 Al0.05 P2 O7 having an excess of phosphates with polybenzimidazole (PBI) and polytetrafluoroethylene (PTFE). The addition of PBI to Sn0.95 Al0.05 P2 O7 - Px Oy powder stabilized the conductivity of the composite, providing higher conductivities than those of stoichiometric Sn0.95 Al0.05 P2 O7. The addition of PTFE to Sn0.95 Al0.05 P2 O7 - Px Oy -PBI powder reduced the conductivity but increased the tensile strength. The resulting composite membrane exhibited a conductivity of 0.04 S cm-1 at 200°C and a tensile strength of 2.30 MPa. Moreover, a fuel cell made with this composite membrane yielded high power densities exceeding 200 mW cm-2 above 100°C and good durability under unhumidified conditions. © 2008 The Electrochemical Society.

DOI： 10.1149/1.2897758

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Intermediate-temperature proton conduction in Al3+-doped SnP2O7 Reviewed

Atsuko Tomita, Norikazu Kajiyama, Toshio Kamiya, Masahiro Nagao, Takashi Hibino

Journal of The Electrochemical Society Vol. 154 ( 12 ) page： B1265-B1269 2007.12

Single-chamber SOFCs using dimethyl ether and ethanol Reviewed

Masaya Yano, Takanori Kawai, Kosuke Okamoto, Masahiro Nagao, Mitsuru Sano, Atsuko Tomita, Takashi Hibino

Journal of The Electrochemical Society Vol. 154 ( 8 ) page： B865-B870 2007.8

Room-temperature hydrogen sensors based on an In3+-doped SnP2O7 proton conductor Reviewed

Atsuko Tomita, Yosuke Namekata, Masahiro Nagao, Takashi Hibino

Journal of The Electrochemical Society Vol. 154 ( 5 ) page： J172-J176 2007.5

Selective catalytic reduction of NOx by H-2 using proton conductors as catalyst supports Reviewed

Tomita Atsuko, Yoshii Takeshi, Teranishi Shinya, Nagao Masahiro, Hibino Takashi

JOURNAL OF CATALYSIS Vol. 247 ( 2 ) page： 137 - 144 2007.4

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

The selective catalytic reduction (SCR) of NOx by H2 was studied using proton-conducting Sn0.9In0.1P2O7 as a catalyst support at 50-350 °C. When a mixture of 800 ppm NO, 1400-8400 ppm H2, and 5% O2 in Ar was introduced to the Pt/C working electrode, NOx was reduced to N2 with N2 selectivity values > 80 %. The reaction mechanism was shown to be based on a mixed potential at the Pt/C working electrode. This mechanism was also applicable to a Sn0.9In0.1P2O7-supported Pt catalyst. H2 SCR over the Pt/Sn0.9In0.1P2O7 catalyst was characterized by a wide operating temperature window (50-350 °C) and remarkable N2 selectivity values (> 80 %). Catalyst performance could be further improved by the addition of Rh to Pt, in which NOx conversion was a maximum 1.4 times higher than that over the Pt/Sn0.9In0.1P2O7 catalyst and N2 selectivity was increased to > 89 % at all temperatures tested. © 2007 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2007.02.001

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Selective catalytic reduction of NOx by H-2 using proton conductors as catalyst supports Reviewed

Atsuko Tomita, Takeshi Yosii, Shinya Teranishi, Masahiro Nagao, Takashi Hibino

Jounal of Catalysis Vol. 247 ( 2 ) page： 137-144 2007.4

Recent advances in single-chamber solid oxide fuel cells: A review Reviewed

Yano Masaya, Tomita Atsuko, Sano Mitsuru, Hibino Takashi

SOLID STATE IONICS Vol. 177 ( 39-40 ) page： 3351 - 3359 2007.1

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Solid State Ionics

Solid oxide fuel cells (SOFCs) have received much recent attention as next generation alternative energy sources. In particular, current efforts are devoted to reducing SOFC costs by downsizing fuel cell systems and lowering the operating temperature. Single-chamber SOFCs (SC-SOFCs) have the potential of meeting the demands. This type of fuel cell consists of only one gas chamber, wherein the anode and cathode are exposed to the same mixture of fuel and oxidant gas. This simplified design offers the possibility of reducing stack components and eliminating the need for sealing. Furthermore, since the principle of operation in the mixture is based on exothermic partial oxidation of the fuel that evolves a large amount of reaction heat, the cell temperature can be efficiently increased, enhancing the ion conductivity of the electrolyte and the catalytic activity of the electrodes. This paper reviews the current status of SC-SOFCs with principal emphasis on the materials aspect. In addition, the benefits and limitations of SC-SOFCs are discussed based on the cell design, performance, and energy efficiency. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ssi.2006.10.014

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A high-performance Mo2C-ZrO2 anode catalyst for intermediate-temperature fuel cells Reviewed

Pilwon Heo, Masahiro Nagao, Mitsuru Sano, Takashi Hibino

Journal of The Electrochemical Society Vol. 154 ( 1 ) page： B53-B56 2007.1

*Recent advances in single-chamber solid oxide fuel cells: A review Reviewed

Masaya Yano, Atsuko Tomita, Mitsuru Sano, Takashi Hibino

Solid State Ionics Vol. 177 ( 39-40 ) page： 3351-3359 2007.1

Sn0.9In0.1P2O7-based organic/inorganic composite membranes Reviewed

Pilwon Heo, Masahiro Nagao, Toshio Kamiya, Mitsuru Sano, Atsuko Tomita, Takashi Hibino

Journal of The Electrochemical Society Vol. 154 ( 1 ) page： B63-B67 2007.1

総説：機能性デバイス材料への応用展開

矢野正也，冨田衷子，日比野高士

セラミックス Vol. 42 page： 867-871 2007

A high-performance Mo2C-ZrO2 anode catalyst for intermediate-temperature fuel cells Reviewed

Heo Pilwon, Nagao Masahiro, Sano Mitsuru, Hibino Takashi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY Vol. 154 ( 1 ) page： B53 - B56 2007

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

Anode performance of non-Pt catalysts for hydrogen oxidation was investigated in intermediate-temperature proton exchange membrane fuel cells. Molybdenum carbide (Mo2 C) showed the highest catalytic activity among the transition metal carbides tested. Furthermore, the catalytic activity of Mo2 C was significantly improved by the addition of ZrO2 to the anode. Transmission electron microscopy and X-ray diffraction measurements revealed that Mo2 C was more highly dispersed in the Mo2 C- ZrO2 C than in the Mo2 CC, suggesting that the particle growth of Mo2 C was suppressed by the addition of ZrO2. We also tested the performance of a fuel cell using Mo2 C- ZrO2 C and Sn0.9 In0.1 P2 O7 as the anode and electrolyte materials, respectively, between 150 and 300°C. At 250°C or higher, the Mo2 C- ZrO2 C anode showed a cell performance comparable to that of the PtC anode. However, cell performance was strongly dependent on the operating temperature, reflecting that the catalytic activity of Mo2 C- ZrO2 was greatly lowered by the decrease in operating temperature. Thus it was concluded that the Mo2 C- ZrO2 catalyst is a promising alternative anode material to Pt, especially at intermediate temperatures. © 2006 The Electrochemical Society.

DOI： 10.1149/1.2382268

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Improved LiMn2O4/graphite Li-ion cells at 55 degrees C Reviewed

Sano Mitsuru, Hattori Takayuki, Hibino Takashi, Fujita Miho

ELECTROCHEMICAL AND SOLID STATE LETTERS Vol. 10 ( 12 ) page： A270 - A273 2007

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemical and Solid-State Letters

Sodium phosphate additives and mixed electrolytes of Li (C2 F5 SO2) 2 N (LiBETI) and LiPF6 were examined to improve cycle performances of Li1.04 Mn1.96 O4 /graphite cells at high temperatures. The cycle performance of those cells exceeded 80% at 100 cycles at 55°C in an optimum combination of a 0.975 M LiBETI and 0.025 M LiPF6 /ethylene carbonate (EC):dimethylcarbonate (DMC) (1:2) electrolyte solution containing 5% of Na4 P2 O7 or 5% of Na5 P3 O10 additive. Such a cycle performance is considered to fulfill the requirement for practical use. © 2007 The Electrochemical Society.

DOI： 10.1149/1.2784141

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Intermediate-temperature proton conduction in Al3+-doped SnP2O7 Reviewed

Tomita Atsuko, Kajiyama Norikazu, Kamiya Toshio, Nagao Masahiro, Hibino Takashi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY Vol. 154 ( 12 ) page： B1265 - B1269 2007

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

Al3+ -doped Sn P2 O7 proton conductors were prepared by controlling the initial composition of the reactants [Sn O2, Al (OH)3, and H3 P O4]. Sn1-x Alx Py Oz with y<2 displayed conductivities approximately two orders of magnitude lower than Sn1-x Alx P2 O7, while those of Sn1-x Alx Py Oz with y>2 exhibited conductivities at a maximum of 1.99 times higher. However, because the conductivity values of Sn1-x Alx Py Oz with y>2 were not stable, the optimal value of y in Sn1-x Alx Py Oz was determined to be 2. Partial substitution of Al3+ for Sn4+ in Sn1-x Alx P2 O7 led to an increase in the conductivity up until x=0.05. As a result, the conductivity reached 0.045 S cm-1 at 100°C, 0.15 S cm-1 at 200°C, and 0.19 S cm-1 at 300°C when the x and y values were 0.05 and 2, respectively. A hydrogen concentration cell with this material demonstrated that the ionic transport number was ∼1, and a fuel cell using this material demonstrated that the dc conductivity was comparable to the ac conductivity. © 2007 The Electrochemical Society.

DOI： 10.1149/1.2789296

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Room-temperature hydrogen sensors based on an In3+-doped SnP2O7 proton conductor Reviewed

Tomita Atsuko, Namekata Yousuke, Nagao Masahiro, Hibino Takashi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY Vol. 154 ( 5 ) page： J172 - J176 2007

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

A potentiometric solid-state gas sensor was fabricated using a proton-conducting Sn0.9 In0.1 P2 O7 electrolyte with an active PtC working electrode in order to study its sensing properties for small quantities (100 ppm 3%) of H2 in air at room temperature. The sensor showed electromotive force (emf) response in the negative direction to changes in the H2 concentration. Furthermore, the emf value varied linearly with the logarithm of the H2 concentration, while it was minimally affected by the water-vapor concentration. The sensing mechanism was shown to be based on the mixed potential at the working electrode through measurements of the polarization curves of H2 and air. The Sn0.9 In0.1 P2 O7 electrolyte was also applied in two single-chamber H2 sensors, wherein PtC and carbon were used as active and inactive electrodes, respectively; these electrodes were attached on the opposite surfaces or on the same surface of the electrolyte. Both single-chamber sensors could exhibit comparable H2 sensitivities, compared to the dual-chamber sensor. © 2007 The Electrochemical Society.

DOI： 10.1149/1.2713702

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Sn0.9In0.1P2O7-based organic/inorganic composite membranes application to intermediate-temperature fuel cells Reviewed

Heo Pilwon, Nagao Masahiro, Kamiya Toshio, Sano Mitsuru, Tomita Atsuko, Hibino Takashi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY Vol. 154 ( 1 ) page： B63 - B67 2007

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

An anhydrous proton conductor, 10 mol % In3+ -doped SnP2 O7 (Sn0.9 In0.1 P2 O7), was composed by 1,8-bis(triethoxysilyl)octane (TES-Oct) and 3-(trihydroxysilyl)-1-propanesulfonic acid ((THS)Pro- SO3 H) and was characterized by structural and electrochemical analysis. The composite membrane with 90 wt % Sn0.9 In0.1 P2 O7 showed high proton conductivities of 0.04 S cm-1 or more between 150 and 200°C in unhumidified air. The packing of the Sn0.9 In0.1 P2 O7 particles in the matrix was relatively uniform, with no formation of pinholes observed. Fuel cell tests verified that the open-circuit voltage was maintained at a constant value of ∼970 mV regardless of the electrolyte thickness (60-200 μm), while the Ohmic resistance was decreased to 0.24 cm2 by reducing the electrolyte thickness to 60 μm. The peak power densities achieved with unhumidified H2 and air were 109 mW cm-2 at 100°C, 149 mW cm-2 at 150°C, and 187 mW cm-2 at 200°C. Furthermore, fuel cell performance was improved by hot-pressing an intermediate layer consisting of Sn0.9 In0.1 P2 O7, PtC, TES-Oct, and (THS)Pro- SO3 H between the electrolyte and cathode. © 2006 The Electrochemical Society.

DOI： 10.1149/1.2388737

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Single-chamber SOFCs using dimethyl ether and ethanol Reviewed

Yano Masaya, Kawai Takanori, Okamoto Kohsuke, Nagao Masahiro, Sano Mitsuru, Tomita Atsuko, Hibino Takashi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY Vol. 154 ( 8 ) page： B865 - B870 2007

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

An anode-supported single-chamber solid oxide fuel cell (SC-SOFC), consisting of a Ce0.9 Gd0.1 O1.9 electrolyte, a Ni- Ce0.8 Sm0.2 O1.8 (SDC) cermet anode, and a Sm0.5 Sr0.5 Co O3 cathode, was operated in a mixture feed of dimethyl ether (DME), ethanol or butane, and air at a furnace temperature of 300°C. This SC-SOFC showed comparatively poor performance for DME and ethanol fuels when compared to the performance for butane fuel, resulting from the relatively small difference in catalytic activity for DME and ethanol oxidation between the anode and the cathode. An effective improvement was achieved by attaching Ru/SDC/Ni and CuZnAl catalyst layers for DME and ethanol, respectively, on the anode surface. As a result, peak power densities of 64 and 117 mW cm-2 were obtained for DME and ethanol, respectively. © 2007 The Electrochemical Society.

DOI： 10.1149/1.2747326

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Papers - HIBINO, Takashi