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Kamimura S.,Kyushu University | Yamada H.,Kyushu University | Yamada H.,Japan National Institute of Advanced Industrial Science and Technology | Xu C.-N.,Kyushu University | And 2 more authors.
Applied Physics Letters | Year: 2013

We report photochromism (PC) in Sr2SnO4:Eu 3+ with layered perovskite-related structure. The Sr 2SnO4:Eu3+ turned purple upon irradiation with UV light (λ < 350 nm), and the colored Sr2SnO 4:Eu3+ returned to its initial colorless state when visible light (λ = 400-700 nm) was irradiated. Furthermore, the PC was strongly dependent on the firing temperature; purple color upon UV irradiation can be enhanced by increasing the firing temperature, which was attributed to an increase of the Sr vacancies in the host lattice from the results of crystal structure analysis. This suggests that controlling the lattice defect plays an important role for enhancing the PC performance. © 2013 American Institute of Physics. Source

Inoishi A.,Kyushu University | Ju Y.W.,Kyushu University | Ida S.,Kyushu University | Ishihara T.,Kyushu University | Ishihara T.,International Institute for Carbon Neutral Energy Research WPI I2CNER
Journal of Power Sources | Year: 2013

Solid oxide fuel cell concept was applied for Fe-air rechargeable battery by using H2/H2O as a mediator for Fe redox. Oxygen partial pressure in Fe set chamber during discharge was monitored simultaneously with O2 sensor for analysis of discharge mechanism. On the cell consisting of Pt anode, Y2O3 stabilized ZrO2(YSZ) electrolyte, and Pt cathode, 10 cycles of charge and discharge was stably performed, although decrease in capacity was observed at initial cycle. Oxygen partial pressure (PO2) was monitored by zirconia oxygen sensor which is used for Fe set chamber. Simultaneous monitoring the oxygen partial pressure during the charge and discharge, the reasonable response of PO2 in Fe set chamber was observed and for discharge, Fe seems to be oxidized to FeO and reduction to Fe was also confirmed. Impedance plots suggested that degradation could be assigned to the increased diffusion overpotential because of the decreased oxidation rate of Fe powder. However, after second cycles, internal resistance of the cell was stable up to 10 cycles examined. Therefore, application of SOFC concept and H2/H2O redox mediator is successfully demonstrated for the Fe-air rechargeable battery. © 2012 Elsevier B.V. All rights reserved. Source

Alahmer A.,University of Tasmania | Alahmer A.,Tafila Technical University | Wang X.,University of Tasmania | Al-Rbaihat R.,Tafila Technical University | And 3 more authors.
Applied Energy | Year: 2016

Performance of an adsorption cooling system driven by solar thermal energy was studied under different climatic conditions. The effects of solar collector area, collector slope, hot water temperature and flow rate on the system performance were investigated using the real-time weather data of two cities: Perth, Australia (a representative city in the southern hemisphere) and Amman, Jordan (a representative city in the northern hemisphere). The simulation results showed that the two cities had similar solar radiation during the summer period and that the solar adsorption chiller could reliably provide cooling at a reasonably high system COP. For residential cooling with a total CPC (Compound Parabolic Collector) solar collector area of 36.22 m2, the average system COP was 0.491 for Perth weather conditions and 0.467 for Amman weather conditions, respectively while the cooling capacity was 10.3 kW for Perth and 8.46 kW for Amman, respectively at peak times. Optimum performance occurred when the system run with the CPC collector slope of around 30°, the solar water storage tank volume of 1.4 m3, inlet hot water temperature of 80 °C, and a hot water flow rate of 0.33 kg/s. An economic analysis was further investigated and the results showed that the solar driven adsorption cooling system could reduce the electricity consumption for Perth and Amman cities by 34% and 28%, respectively in comparison to a conventional vapour compression cooling system. © 2016 Elsevier Ltd. Source

Yamauchi M.,International Institute for Carbon Neutral Energy Research WPI I2CNER | Ozawa N.,Institute for Materials Research | Kubo M.,Institute for Materials Research
Chemical Record | Year: 2016

Renewable electricity must be utilized to usefully suppress the atmospheric CO2 concentration and slow the progression of global warming. We have thus proposed a new concept involving CO2-free electric power circulation systems via highly selective electrochemical reactions of alcohol/carboxylic acid redox couples. Design concepts for nanocatalysts able to catalyze highly selective electrochemical reactions are provided from both experimental and quantum mechanical perspectives. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Wang S.,Kyushu University | Inoishi A.,International Institute for Carbon Neutral Energy Research WPI I2CNER | Hong J.-E.,International Institute for Carbon Neutral Energy Research WPI I2CNER | Ju Y.-W.,International Institute for Carbon Neutral Energy Research WPI I2CNER | And 3 more authors.
Journal of Materials Chemistry A | Year: 2013

A solid oxide electrolysis cell for reducing CO2 to CO was studied using a LaGaO3-based electrolyte at intermediate temperatures (973-1173 K). Various metals were examined as cathodes for CO2 reduction, and it was found that Ni shows high activity. However, coke formation was observed during the initial period. Furthermore, we found that the electrolysis current could be greatly improved by adding Fe to Ni, resulting in a current density of 1.84 A cm-2 at 1.6 V and 1073 K on a Ni-Fe (9:1) cathode. SEM observation suggests that improved cathodic activity can be explained by stabilizing Ni fine particles with the addition of Fe. Therefore, diffusion resistance can be decreased by adding Fe to Ni. The formation rate of CO is slightly lower than the consumption rate of CO2, suggesting coke formation during the initial period. However, stable CO2 electrolysis can be performed for at least 12 h, and Fe addition is effective for increasing long-term stability of electrolysis. © 2013 The Royal Society of Chemistry. Source

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