| Project/Area Number |
19K15676
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 36020:Energy-related chemistry
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| Research Institution | Shinshu University |
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Principal Investigator |
徐 貞淑 信州大学, 先鋭領域融合研究群先鋭材料研究所, 特任助教 (60837102)
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| Project Period (FY) |
2019-04-01 – 2020-03-31
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| Project Status |
Discontinued (Fiscal Year 2019)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2022: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2021: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2020: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2019: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
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| Keywords | solar water oxidation / perovskite oxynitrides / surface defects / low onset potential / defects / oxygen evolution |
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| Outline of Research at the Start |
n-type perovskite oxynitrides AB(O,N)3 (A=Ca, Sr, Ba and La; B=Ti, Ta and Nb) are very promising semiconductors for solar water splitting producing hydrogen because they are capable of absorbing a wide wavelenght range of visible light. However, high onset potential of the oxynitride photoanodes for water oxidation is a great obstacle to application to water splitting devices. In this research, doping of foreign elements into the AB(O,N)3 is mainly studied for improvement in semiconducting properties of the oxynitrides, leading to low onset potential for the solar water oxidation.
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| Outline of Annual Research Achievements |
The Perovskite-type BaTaO2N had been studied as a starting material for this research based on efficient solar water oxidation. BaTaO2N was successfully prepared from layered perovskite, Ba-rich Ba5Ta4O15 to suppress surface defects such as reduced species of Ta4+ and/or Ta3+ during the high temperature nitridation under NH3 flow at 1223 K for 30 h. Subsequently, the annealing treatment of the nitrided product in an Ar flow was performed to reduce additional oxygen impurities and/or nitrogen vacancy and thus to decrease the recombination of photogenerated charges during the solar water oxidation.
The decreased defect densities related to Ta and O/N species on the BaTaO2N particles were determined by X-ray photoelectron spectroscopy and oxygen-nitrogen combustion analysis, respectively. These approaches were very effective at suppressing the surface defects and impurities on BaTaO2N. Consequently, the photocurrent density at 1.23 VRHE of 6.5 mA cm-2 was generated during the photoelectrochemical water splitting over a particulate BaTaO2N photoanode and the onset potential driving actual anodic photocurrent was shifted more negatively to 0.6 VRHE, providing a half-cell solar-to-hydrogen energy conversion efficiency of 1.4%. This is a new record for a photoanode based on perovskite-type AB(O,N)3.
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