研究課題/領域番号 |
19K15676
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研究種目 |
若手研究
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配分区分 | 基金 |
審査区分 |
小区分36020:エネルギー関連化学
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研究機関 | 信州大学 |
研究代表者 |
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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研究期間 (年度) |
2019-04-01 – 2020-03-31
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研究課題ステータス |
中途終了 (2019年度)
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配分額 *注記 |
4,160千円 (直接経費: 3,200千円、間接経費: 960千円)
2022年度: 390千円 (直接経費: 300千円、間接経費: 90千円)
2021年度: 520千円 (直接経費: 400千円、間接経費: 120千円)
2020年度: 520千円 (直接経費: 400千円、間接経費: 120千円)
2019年度: 2,730千円 (直接経費: 2,100千円、間接経費: 630千円)
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キーワード | solar water oxidation / perovskite oxynitrides / surface defects / low onset potential / defects / oxygen evolution |
研究開始時の研究の概要 |
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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研究実績の概要 |
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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