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27. Development Status of SOFC Cell and Stack Technology at NRC-IFCI

Author

Tuck, Adam, primary, Zhang, Xinge, additional, Hui, Rob, additional, Qu, Wei, additional, Decès-Petit, Cyrille, additional, Xie, Yongsong, additional, Roller, Justin, additional, Min, Kyong-Bok, additional, Robertson, Mark, additional, Yick, Sing, additional, Maric, Radenka, additional, and Ghosh, Dave, additional

Published
2019
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28. Electronic Conductivity and Stability of Doped Titania (Ti1−XMXO2, M = Nb, Ru, and Ta)A Density Functional Theory-Based Comparison

Author

Dy, Eben, Hui, Rob, Zhang, Jiujun, Liu, Zhong-Sheng, and Shi, Zheng

Abstract

The structure, electrical conductivity, and stability of Nb-, Ru-, and Ta-doped titania were compared by density functional theory. Both anatase and rutile structures were investigated. Doping causes lattice expansion in all cases. The mechanism by which Ru-doping induces electrical conductivity in titania differs from those by Ta- and Nb-doping. Ru-doping fills the titania band gap primarily with its own d-electrons. On the other hand, Ta- and Nb-doping shift the Fermi level to the originally unfilled conduction states. Substitution free energy calculations indicate that a uniform Ti0.75M0.25O2solution is favorable for Nb- and Ta-doping but unfavorable for Ru-doping. In addition, we also considered the effect of dopant concentration on the electrical conductivity of doped titania in the rutile phase. For Nb- and Ta-doping, increasing dopant concentration above mole fractions of 0.0625 and 0.125, respectively, gives diminished increment in Fermi level electron density. On the other hand, electron density at the Fermi level of Ru-doped rutile is more linearly dependent on Ru mole fraction.

Published
2024
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29. Proton conductivity and stability of Ba2In2O5 in hydrogen containing atmospheres

Author

Jankovic, Jasna, Wilkinson, David P., and Hui, Rob

Subjects
fuel cell, proton conductive ceramics, Ba2In2O5, intermediate temperature
Abstract

Ba₂In₂O₅ is one of the oxygen deficient ceramic materials widely investigated for both oxygen ion conduction and proton conduction in oxidizing atmospheres. However, its electrochemical properties have not been studied in hydrogen containing atmospheres. In this work, the electrical conductivity of Ba₂In₂O₅ in hydrogen containing atmospheres was investigated by ac impedance spectroscopy in the temperature range between 100 and 500°C and compared to its conductivity in air and nitrogen in order to estimate the contribution of proton conductivity to the total conductivity. A stable electrical conductivity of over 0.3 S/cm was achieved in the temperature range of 300–480°C in a 50% vol H₂/50% vol N₂ atmosphere. Electromotive force measurements (and complimentary open circuit cell voltage measurements) revealed high proton transport numbers over the temperature range. Ba₂In₂O₅ shows chemical stability in hydrogen containing atmospheres at temperatures up to 480°C, while decomposing at higher temperatures. Mechanical instability was noticed in humid atmospheres at 400°C and above. This previously unreported high conductivity in H₂ atmosphere creates an opportunity for use of Ba₂In₂O₅ as a proton conductive material for a range of intermediate temperature electrochemical devices.

Published
2010

49. Thin Film Solid Oxide Fuel Cells Deposited by Spray Pyrolysis

Author

Xie, Yongsong, primary, Neagu, Roberto, additional, Hsu, Ching-Shiung, additional, Zhang, Xinge, additional, Decès-Petit, Cyrille, additional, Qu, Wei, additional, Hui, Rob, additional, Yick, Sing, additional, Robertson, Mark, additional, Maric, Radenka, additional, and Ghosh, Dave, additional

Published
2010
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