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Uchida H.,Clean Energy Research Center | Uchida H.,Fuel Cell Nanomaterials Center | Puengjinda P.,Clean Energy Research Center | Miyano K.,Yamanashi University | And 4 more authors.
ECS Transactions | Year: 2013

For the hydrogen electrode in the solid oxide electrolysis cell (SOEC), nanometer-sized Ni catalysts were highly dispersed on samaria-doped ceria (SDC). It was found that the current density on Ni-dispersed SDC at 900 °C and the potential of -1.0 V vs. air increased by 1.5 times with decreasing the Ni particle size from 70 nm to 40 nm, even when the Ni-loading was decreased from 17 vol.% to 8 vol.%. © The Electrochemical Society.

Ono H.,Japan Science and Technology Agency | Miyake J.,Yamanashi University | Miyake J.,Japan Science and Technology Agency | Uchida M.,Fuel Cell Nanomaterials Center | And 4 more authors.
Journal of Materials Chemistry A | Year: 2015

A novel series of ammonium-containing copolymers (QPAFs) were synthesized as anion exchange membranes for alkaline fuel cell applications. The precursor copolymers (Mw = 28.3-90.1 kDa) composed of perfluoroalkylene and phenylene groups were obtained by a nickel promoted polycondensation reaction. Chloromethylation and quaternization reactions of the precursors provided thin and ductile QPAF membranes with ion exchange capacity (IEC) ranging from 0.79 to 1.74 meq g-1. The QPAF membranes exhibited a phase-separated morphology based on the hydrophilic/hydrophobic differences in the main chain structure. The QPAF membrane with an optimized copolymer composition and IEC = 1.26 meq g-1 showed high hydroxide ion conductivity (95.5 mS cm-1 in water at 80 °C), excellent mechanical properties (large elongation at break (218%)), and reasonable alkaline stability at 80 °C. An alkaline fuel cell using the QPAF as the membrane and electrode binder achieved the maximum power density of 139 mW cm-2 at a current density of 420 mA cm-2. © 2015 The Royal Society of Chemistry.

Uchida H.,Clean Energy Research Center | Uchida H.,Fuel Cell Nanomaterials Center | Nishida R.,Yamanashi University | Tatsuzawa M.,Yamanashi University | And 3 more authors.
ECS Transactions | Year: 2011

We have synthesized nanometer-sized Ni 100-xCo x (X = 0 to 50) alloy catalysts supported on hollow particles of samaria-doped ceria [SDC, (CeO 2) 0.8(SmO 1.5) 0.2] by spraying a mixed solution of the corresponding metal nitrates and acetates in an atmospheric pressure plasma. The performances of Ni 80Co 20/SDC catalyst in both SOFC and steam electrolysis (p[H 2O] = 0.6 atm) were found to be the highest among alloys and pure Ni (X = 0) supported on the SDC at 800 to 900°C. ©The Electrochemical Society.

Bae B.,Fuel Cell Nanomaterials Center | Hoshi T.,Yamanashi University | Miyatake K.,Fuel Cell Nanomaterials Center | Miyatake K.,Yamanashi University | Watanabe M.,Fuel Cell Nanomaterials Center
Macromolecules | Year: 2011

Poly(arylene ether sulfone) multiblock copoly. were synthesized via oligomeric sulfonation. The successful oligomeric sulfonation enabled multiblock copolymer membranes with different hydrophobic block moiety (biphenyl and naphthalene units). High local concentration of sulfonic acid groups within the hydrophilic blocks enhanced the phase separation between hydrophilic and hydrophobic moiety. Rigid, nonpolar, and planar hydrophobic moiety such as naphthalene groups were effective in increasing proton conductivity and decreasing gas permeability. The multiblock copolymers with naphthalene hydrophobic units with IEC = 2.01 mequiv/g showed comparable proton conductivity to Nafion NRE 212 membrane (0.91 mequiv/g) at >40% RH. The longer blocks were found to increase a characteristic factor (ratio of the proton conductivity to the water volume fraction) as well as phase separation. The membrane showed relatively low oxidative stability under Fenton's test conditions due to higher water uptake and swelling. However, low gas permeability could compensate this drawback for fuel cell applications. © 2011 American Chemical Society.

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