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Papers by Author: Hiroshige Matsumoto

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Ni-Fe-LaGaO₃ Based Alloy Anode Cermet for Direct Hydrocarbon Type Solid Oxide Fuel Cell Using LaGaO₃ Electrolyte

Authors: Hao Zhong, Tatsumi Ishihara, Hiroshige Matsumoto

Abstract: Cermet anode of NiFe(9:1)-La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) (90:10 weight ratio) was studied for direct CH4 fueled SOFC operating at intermediate temperature. In case of NiFe bimetal anode, power density of the cell decreased drastically after operation under CH4 feeding condition. On the other hand, mixing Sm doped CeO2, MgO, or LSGM is effective for improving the long term stability. The cell with NiFe-LSGM anode exhibited much stable power density under CH4 feeding condition. Deposition of coke was also studied by Raman spectroscopy and no coke deposition was observed after 15 h operation. Since the surface activity of this anode is high, power density was hardly dependent on PCH4.It was found that NiFe-LSGM10 shows a high tolerance against the coke deposition under CH4 feeding condition.

1112

Intermediate Temperature Steam Electrolysis Using Doped Lanthanum Gallate Solid Electrolyte (2) Effects of CeO₂ Interlayer on Activity

Authors: Nitiphong Jirathiwathanakul, Hiroshige Matsumoto, Tatsumi Ishihara

Abstract: Steam electrolysis is attracting much interest method to produce hydrogen and also the new energy recovery process of wasted heat energy. Up to now, Y2O3 stabilized ZrO2 (YSZ) has been used for a solid electrolyte and so the operating temperature is limited down to 1273K. This study is focused on increasing the performance of steam electrolysis by using LaGaO3 based oxide for electrolyte at intermediate temperature of 873 K, which is upper limit of the obtainable wasted heat. It was found that the formation amount of H2 is almost obeyed the Faraday law up to 1.8 V suggesting that the ionic transport number of oxide ion in LaGaO3 was kept to be 1 under the steam electrolysis condition. The electrolyzing current is improved as following order; La0.6Sr0.4CoO3

1005

Development of Honeycomb-Type Solid Oxide Fuel Cell Consisting of LaGaO₃ Electrolyte

Authors: Hao Zhong, Hiroshige Matsumoto, Tatsumi Ishihara, Akira Toriyama

Abstract: La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) -based honeycomb cell was first time successfully built and operated in the case of single-wall used condition and the full 4-walls cell one. Power generation characteristic of this honeycomb cell was measured from 700°C to 900°C by using various electrochemical techniques including polarization, current interruption and impedance spectrometry. The LSGM honeycomb cell shows the exact high power density compared with the ZrO2 based cell at the operating temperature range, and its value is 394 and 252 mW/cm2 at 800°C and 700°C, respectively. Thermal stability of this honeycomb cell is also studied and it is seen that the good performance through several times thermal cycling is observed. The 4-walls’s cell stack is successfully working at 800°C, and the volumetric power density is achieved to a value of about 700 mW/cm3.

969

Effects of Dye Mixing on Photocatalytic Splitting of H₂O into H₂ and O₂ on KTaO₃

Authors: Hidehisa Hagiwara, Hiroshige Matsumoto, Tatsumi Ishihara

Abstract: Effects of mixing dye sensitizer for the photocatalytic activity of dye-sensitized Pt/K0.95Ta0.92Zr0.08O3 was investigated. It was found that the photocatalytic activity was greatly improved by mixing dye sensitizer on the catalyst, and among the examined combination of organic dyes, the highest photocatalytic activity was obtained by mixing Cr-tetraphenylporphyrin (Cr-TPP) and Pentametylene bis[4-(10, 15, 20-triphenylporphine-5-yl)benzoate] dizinc(ΙΙ) (Zn-TPP dimer). In order to identify the effect of dye sensitizer, photovoltaic behavior of the dye-sensitized KTaO3 was investigated. The lifetime of the photo-exited electron and hole can be improved by coating with dye sensitizer. Thus, the effect of porphyrinoids would be explained by the improved efficiency of charge separation.

Ni-Fe Bimetallic Anode for Intermediate Temperature Solid Oxide Fuel Cells Using LaGaO₃ Based Oxide Electrolyte

Authors: Tatsumi Ishihara, Masashi Shinagawa, Akira Kawakami, Hiroshige Matsumoto

Abstract: Effects of various additives to Ni anode on SOFC using La0.9Sr0.1Ga0.8Mg0.2O3 based oxide were investigated in this study. Among the examined additives, it was found that the addition of small amount of Fe is highly effective for increasing the anodic activity. When 5 wt% Fe was added to Ni anode, the anodic overpotential was as small as 34 mV at 873 K, 0.1A/cm2, which is almost half of pure Ni anode. Since the estimated activation energy for anodic reaction decreased, addition of Fe to Ni seems to be effective for increasing the activity of Ni for anodic reaction. XRD measurement after power generating property suggests that added Fe was formed alloy with Ni. SEM observation shows the high dispersion of Ni metal was sustained by addition of small amount of Fe. Consequently, this study reveals that Ni-Fe bimetal is highly active for anodic reaction of SOFCs at decreased temperature.

1350

Application of Protonic Conduction in Perovskite-Type Oxides: Mixed Proton-Electron-Conducting Membrane for Hydrogen Separation

Authors: Hiroshige Matsumoto

Abstract: Hydrogen separation is one of the key techniques for the forthcoming hydrogen economy. This paper describes a possible electrochemical method and materials for hydrogen separation: mixed proton-electron-conducting membrane that can permeate hydrogen selectively from hydrogen-containing gases, such as reformed gases of hydrocarbons. Proton-conducting perovskite-type solid electrolytes are first introduced as the base material of the mixed conductor. Some transition metal-doped perovskites are shown to have a mixed conductivity of protonic and electronic charge carriers, revealed by electrochemical and X-ray-spectroscopic measurements.

2024