Shinya Teranishi

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

Multilayered Ce 0.9 Gd 0.1 O 1.95 /BaCe 0.8 Y 0.2 O 3-α /Ce 0.9 Gd 0.1 O 1.95 (GDC/BCY/GDC) electrolytes were prepared by tape casting on a Ni-Ce 0.8 Sm 0.2 O 1 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.

Proton-Conducting Thin Film Grown on Yttria-Stabilized Zirconia Surface for Ammonia Gas Sensing Technologies

We demonstrate an approach to impart both proton conduction and solid acidity to the surface of yttria-stabilized zirconia (YSZ). By reacting a YSZ substrate with liquid H 3 PO 4 at 500°C, a thin Zr 1-x Y x P 2 O 7 film is grown on the substrate, which shows proton conductivity dependence on humidity and strong acid sites interacting with basic ammonia gas. This technique can be applied to gas sensor devices, yielding a remarkably sensitive and selective response to low concentrations (parts per million) of ammonia. Another important achievement of this technique is the realization of sensing properties in spite of using a conventional Pt electrode.

Nano-Sized Electrochemical Reactors for Selective NOx Reduction

The present study proposed a scheme for the reaction between NOx and C 3 H 6 in the presence of excess O 2 over a proton-conducting Sn 0.9 In 0.1 P 2 O 7 -supported PtRh catalyst. C 3 H 6 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 N 2 and H 2 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/Sn 0.9 In 0.1 P 2 O 7 , followed by self-discharge. This series of reactions could be clearly distinguished from conventional catalytic reduction of NOx by C 3 H 6 .

Intermediate-temperature electrolysis of energy grass Miscanthus sinensis for sustainable hydrogen production

Biohydrogen produced from the electrolysis of biomass is promising because the onset voltages are less than 1.0 V and comparable to those of water and alcohol-water electrolysis. The present study focuses on Miscanthus sinensis as a model grass because of its abundance and ease of cultivation in Japan. The electrochemical performance and hydrogen formation properties of electrolysis cells using grass as a biohydrogen source were evaluated at intermediate temperature to achieve electrolysis. The components, such as holocellulose, cellulose, lignin, and extractives, were separated from Miscanthus sinensis to understand the reactions of Miscanthus sinensis in the electrolysis cell. The relatively high resistivity and low current-voltage performance of an electrolysis cell using lignin were responsible for degradation of the electrolysis properties compared to those with pure cellulose or holocellulose as biohydrogen resources. Biohydrogen was formed according to Faraday’s law and evolved continuously at 0.1 A cm−2 for 3,000 seconds.