研究者詳細 - 長尾　征洋

論文 - 長尾　征洋

分割表示 95 件中 81 - 95 件目／全件表示 >>

Electrochemical reduction of NOx at intermediate temperatures using a proton-conducting In3+-doped SnP2O7 electrolyte

Nagao, M; Yoshii, T; Hibino, T; Sano, M; Tomita, A

ELECTROCHEMICAL AND SOLID STATE LETTERS 9 巻 ( 2 ) 頁： J1 - J4 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Electrochemical and Solid-State Letters

In 3+-doped SnP 2O 7 was used as the electrolyte in an electrochemical cell for the reduction of NO between 150 and 300°C in the presence of excess O 2. NO was reduced to N 2 at a Pt/C cathode when current was applied to the cell. The electrocatalytic activity of the cathode for the reduction of NO was shown to be highest at 250°C. The addition of Ba species (an oxide/carbonate mixture) to the cathode further promoted the reduction of NO by adsorbing NO more selectively than O 2 on the surface. A resulting current efficiency of 5.81% was achieved in a 2% O 2 atmosphere. © 2005 The Electrochemical Society. All rights reserved.

DOI： 10.1149/1.2149213

Web of Science

Scopus

Comparative performance of anode-supported SOFCs using a thin Ce0.9Gd0.1O1.95 electrolyte with an incorporated BaCe0.8Y0.2O3-α layer in hydrogen and methane

Tomita, A; Teranishi, S; Nagao, M; Hibino, T; Sano, M

JOURNAL OF THE ELECTROCHEMICAL SOCIETY 153 巻 ( 6 ) 頁： A956 - A960 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the Electrochemical Society

Multilayered Ce0.9 Gd0.1 O1.95 Ba Ce0.8 Y0.2 O3-α Ce0.9 Gd0.1 O1.95 (GDCBCYGDC) electrolytes were prepared by tape casting on a Ni- Ce0.8 Sm0.2 O1.9 anode support. The overall electrolyte thickness ranged from 30 to 35 μm, including a 3 μm thick BCY layer. When the multilayered electrolyte cell was tested with hydrogen at the anode and air at the cathode in the temperature range of 500-700°C, it yielded open-circuit voltages (OCVs) of 846-1024 mV, which were higher than the OCVs of 753-933 mV obtained for a single-layered GDC electrolyte cell under the same conditions. The corresponding peak power densities reached 273, 731, and 1025 mW cm-2 at 500, 600, and 700°C, respectively. The multilayered electrolyte cell could also be applied to direct methane solid oxide fuel cell (SOFC) and single-chamber SOFC operating in a mixture of methane and air. These SOFCs yielded OCVs of 880-950 mV and reasonable power densities without coking. © 2006 The Electrochemical Society.

DOI： 10.1149/1.2186184

Web of Science

Scopus

Performance of an intermediate-temperature fuel cell using a proton-conducting Sn0.9In0.1P2O7 electrolyte

Heo, P; Shibata, H; Nagao, M; Hibino, T; Sano, M

JOURNAL OF THE ELECTROCHEMICAL SOCIETY 153 巻 ( 5 ) 頁： A897 - A901 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the Electrochemical Society

Performance of a fuel cell using Sn0.9 In0.1 P2 O7 as the electrolyte was evaluated in the temperature range of 150-300°C under unhumidified conditions. The IR drop and electrode overpotential of the cell were measured separately by the current interruption method. The dc conductivity values of the electrolyte between 150 and 300°C, estimated from the IR drop, were comparable to the ac conductivity values (1.48× 10-1 -1.95× 10-1 S cm-1) of the electrolyte. The cell performance was improved by forming an intermediate layer consisting of Sn0.9 In0.1 P2 O7 and PtC catalyst powders at the interface between the electrolyte and cathode, which significantly reduced the cathode polarization. As a result, the peak power density reached 264 mW cm-2 at 250°C using the 0.35-mm -thick electrolyte. The present fuel cell also showed high stability at low relative humidities (p H2 O ≈0.0075 atm) and 10% CO concentration. © 2006 The Electrochemical Society. All rights reserved.

DOI： 10.1149/1.2183927

Web of Science

Scopus

Proton conduction in In3+-doped SnP<inf>2</inf>O<inf>7</inf> with various P/(Sn+In) ratios

Nagao M., Heo P., Kamiya T., Hibino T., Sano M., Tomita A.

ECS Transactions 2 巻 ( 10 ) 頁： 43 - 49 2006年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：ECS Transactions

A proton conducting, 10 mol% In3+-doped SnP2O 7 (Sn0.9In0.1 P2O7) was characterized by thermogravimetric analysis (TGA), transmission electron microscope (TEM) measurement, and electrochemical techniques. We prepared Sn0.9In0.1P2=x07±x samples with various P/(Sn+In) molar ratios from 1.7 to 2.6 through the control of the amount of phosphoric acid at the preparation process in order to examine electrochemical properties and thermal stabilities. Sn0.9In 0.1P2O7 with a stoichiometric P/(Sn+In) molar ratio of 2.0 showed a proton conductivity of about 0.19 S cm-1 at 250°C under unhumidified conditions. When the P/(Sn+In) molar ratios were over 2.0, the formation of amorphous layer composed of phosphorus compounds were observed over the surface of Sn0.9In0.1P 2O7 particles. The proton conductivity slightly increased with increasing the P/(Sn+In) molar ratios from 2.0 to 2.6. It is considered that the amorphous layer enhanced the proton conductivity by surface conduction. On the other hand, the thermal stability of this amorphous layer during heating-cooling cycle was not enough high to apply to electrochemical devises. As a result, it is important to prepare Sn0.9In0.1P 2O7 with the P/(Sn+In) molar ratio of 2.0 to achieve both sufficient proton conductivity and high thermal stability. Copyright The Electrochemical Society.

DOI： 10.1149/1.2408942

Scopus

Proton conduction in In3+-doped SnP2O7 at intermediate temperatures

Nagao, M; Kamiya, T; Heo, P; Tomita, A; Hibino, T; Sano, M

JOURNAL OF THE ELECTROCHEMICAL SOCIETY 153 巻 ( 8 ) 頁： A1604 - A1609 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the Electrochemical Society

SnP2 O7 -based proton conductors were characterized by Fourier transform infrared spectroscopy (FTIR), temperature-programmed desorption (TPD), X-ray diffraction (XRD), and electrochemical techniques. Undoped SnP2 O7 showed overall conductivities greater than 10-2 S cm-1 in the temperature range of 75-300°C. The proton transport numbers of this material at 250°C under various conditions were estimated, based on the ratio of the electromotive force of the galvanic cells to the theoretical values, to be 0.97-0.99 in humidified H2 and 0.89-0.92 under fuel cell conditions. Partial substitution of In3+ for Sn4+ led to an increase in the proton conductivity (from 5.56× 10-2 to 1.95× 10-1 S cm-1 at 250°C, for example). FTIR and TPD measurements revealed that the effects of doping on the proton conductivity could be attributed to an increase in the proton concentration in the bulk Sn1-x Inx P2 O7. The deficiency of P2 O7 ions in the Sn1-x Inx P2 O7 bulk decreased the proton conductivity by several orders of magnitude, which was explained as due to a decrease in the proton mobility rather than the proton concentration. The mechanism of proton incorporation and conduction is examined and discussed in detail. © 2006 The Electrochemical Society. All rights reserved.

DOI： 10.1149/1.2210669

Web of Science

Scopus

A high performance Pt-free anode for intermediate-temperature fuel cells

Heo P., Nagao M., Sano M., Hibino T.

ECS Transactions 3 巻 ( 1 ) 頁： 453 - 458 2006年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：ECS Transactions

Proton exchange membrane fuel cells (PEMFCs) are among the most promising power sources for vehicular and residential applications because of their clean and efficient energy conversion. However, these fuel cells require expensive Pt-based electrodes, which raise the cost of fuel-cell systems considerably. Here, we propose an approach to solving this problem by combining a molybdenum carbide (Mo2C) catalyst with an In3+-doped SnP 2O7 electrolyte. The resulting fuel cell can operate in the temperature range of 150 to 300°C, providing the high catalytic activity of Mo2C for electrochemical hydrogen oxidation, which is comparable to that of a Pt anode catalyst. Another important advantage of this fuel cell is that the Mo2C anode catalyst showed perfect tolerance to 10%CO. copyright The Electrochemical Society.

DOI： 10.1149/1.2356166

Scopus

A Proton-Conducting In^<3+>-Doped SnP_2O_7 Electrolyte for Intermediate Temperature Fuel Cells 査読有り

長尾征洋

Electrochemical and Solid-State Letters 9 2006年

Proton conduction in In^<3+>-doped SnP_2O_7 at intermediate temperatures 査読有り

長尾征洋

Journal of The Electrochemical Society 153 2006年

Intermediate-temperature NOx sensor based on an In^<3+>-doped SnP_2O_7 proton conductor 査読有り

長尾征洋

Electrochemical and Solid-State Letters 9 2006年

Electrochemical reduction of NO_x at intermediate temperatures using a proton-conducting In^<3+>-Doped SnP_2O_7 electrolyte 査読有り

長尾征洋

Electrochemical and Solid-State Letters 9 2006年

「総説」MP2O7系固体電解質のプロトン導電性とその応用

長尾征洋, 冨田衷子, 日比野高士, 佐野充

電気化学および工業物理化学 73 巻頁： 846-850 2005年

Single-Chamber SOFCs with a Ce0.9Gd0.1O1.95 Electrolyte Film for Low-Temperature Operation 査読有り

Atsuko Tomita, Daisuke Hirabayashi, Takashi Hibino, Masahiro Nagao, Mitsuru Sano

Electrochemical and Solid-State Letters 8 巻 ( 1 ) 頁： A63-A65 2004年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

Single-chamber solid oxide fuel cells (SOFCs) with an anode-supported Ce0.9Gd0.1O1.95 electrolyte were operated in a mixture of butane and air at furnace temperatures of 200-300°C. The electromotive force (emf) of the cell and the voltage drop were strongly influenced by the catalytic activity of the anode for the partial oxidation of butane. The promotion of hydrogen formation by the addition of Ru to the anode caused an increase in the emf and a reduction in the voltage drop. As a result, stable power densities of 44 and 176 mW cm–2 were obtained at 200 and 300°C, respectively.

Design of a Reduction-Resistant Ce0.8Sm0.2O1.9 Electrolyte Through Growth of a Thin BaCe1–xSmxO3– Layer over Electrolyte Surface 査読有り

Daisuke Hirabayashi, Atsuko Tomita, Takashi Hibino, Masahiro Nagao, Mitsuru Sano

Electrochemical and Solid-State Letters 7 巻 ( 10 ) 頁： A318-A320 2004年9月

記述言語：英語掲載種別：研究論文（学術雑誌）

A method that can block off electronic current through a samaria-doped ceria (SDC, Ce0.8Sm0.2O1.9) electrolyte is proposed. A thin BaCeO3-based layer 12 µm thick was grown by a solid-state reaction of the electrolyte substrate and a BaO film deposited previously over the substrate surface at 1500°C. A homogeneous junction between the layer and the electrolyte was formed, thus allowing no delamination and cracking of the layer. Tolerance of this layer to CO2 was high enough to suppress decomposition into BaCO3 and CeO2. Open-circuit voltages of a hydrogen-air fuel cell with the coated SDC electrolyte were near 1 V or more in the range of 600-950°C. The resulting peak power density was higher than that of a fuel cell with an uncoated SDC electrolyte.

Solid oxide fuel cells operating without using an anode material 査読有り

Daisuke Hirabayashi, Atsuko Tomita, Munuel E. Brito, Takashi Hibino, Ushio Harada, Masahiro Nagao, Mitsuru Sano

Solid State Ionics 168 巻 ( 1 ) 頁： 23-29 2004年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

We proposed a new type of solid oxide fuel cell (SOFC) operating without using an anode material, where the anode was spontaneously formed by reduction of the electrolyte surface under reducing gas conditions. A BaCe0.76Y0.20Pr0.04O3−α electrolyte most successfully met this criterion. This material showed high mixed protonic–electronic conduction, whereas the open circuit voltage (OCV) of the cell was slightly lower than the theoretical value. The resulting SOFC exhibited reasonable fuel cell performances together with a good stability to thermal and redox cyclings and high resistance to carbon deposition up to 800 °C for dry methane, ethane, and propane.

Author Keywords: Solid oxide fuel cells; BaCe0.76Y0.20Pr0.04O3−α; Anode material

SOFC-type microreactors that generate hydrogen for PEFC applications 査読有り

Atsuko Tomita, Daisuke Hirabayashi, Masahiro Nagao, Mitsuru Sano, Takashi Hibino

Solid State Ionics 174 巻頁： 9-13 2004年

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