2019 Fiscal Year Annual Research Report
Efficient solar-driven water oxidation using particulate perovskite oxynitrides by defect engineering
| Project/Area Number |
19K15676
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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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| Keywords | solar water oxidation / perovskite oxynitrides / surface defects |
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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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