Elucidation of band alignment in photocatalysts to obtain design strategy based on semiconductor physics
| Project/Area Number |
18H03772
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Medium-sized Section 21:Electrical and electronic engineering and related fields
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
佐藤 正寛 東京大学, 先端科学技術研究センター, 助教 (40805769)
藤井 克司 国立研究開発法人理化学研究所, 光量子工学研究センター, 研究員 (80444016)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥44,720,000 (Direct Cost: ¥34,400,000、Indirect Cost: ¥10,320,000)
Fiscal Year 2020: ¥11,180,000 (Direct Cost: ¥8,600,000、Indirect Cost: ¥2,580,000)
Fiscal Year 2019: ¥14,560,000 (Direct Cost: ¥11,200,000、Indirect Cost: ¥3,360,000)
Fiscal Year 2018: ¥18,980,000 (Direct Cost: ¥14,600,000、Indirect Cost: ¥4,380,000)
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| Keywords | 光触媒 / 半導体物理 / 界面準位 / バンドアラインメント / 水分解 / 水素 / 光起電力 / 半導体 |
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| Outline of Final Research Achievements |
Single crystal substrates were used as semiconductor photocatalysts to systematically investigate the effects of defect levels on the semiconductor surface and surface chemical species originating from the electrolyte on the band bending and photovoltage at the semiconductor/electrolyte interface. All of the GaN, SrTiO3, and TiO2 substrates formed a Schottky junction-like band alignment at the interface with an electrolyte, but not only the crystal defects on the semiconductor surface. In addition to the crystal defects on the surface of the semiconductor, surface chemical species also functioned as recombination centers for photoexcited carriers, pinning the Fermi level under light irradiation and preventing the quasi-Fermi level from reaching the potential required for hydrogen and oxygen production. In addition, Pt, which is used as an co-catalyst for hydrogen production, was found to be in ohmic contact with GaN and STO, contrary to expectations based on its work function.
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| Academic Significance and Societal Importance of the Research Achievements |
半導体光触媒の材料探索には，バンド端のエネルギーと水素・酸素発生電位との整合関係が高効率水分解の指標として主に考慮されてきた．本研究により，実際に水素・酸素発生の進行を司る光励起キャリアの擬フェルミエネルギーは，バンド端のエネルギーのみならず半導体／電解液界面での欠陥や半導体表面の化学種を介したキャリアの再結合により，とくに光強度が十分でない場合にピニングされることが明らかになった．本研究で開発した開放電圧を幅広い光強度範囲で観察する手法により，このようなフェルミエネルギーのピニングを定量化することが可能となり，高効率光触媒に必要な半導体の表面処理を最適化する指針が見出された．
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Report
(4 results)
Research Products
(19 results)
