電気化学的に誘導された δ-MnO2の水酸化のための活性サイトが明らかになった: スピネルから層への相移行の役割
1Collaborative Innovation Center of Chemistry for Energy Material, Key Laboratory of Computational Physical Science (Ministry of Education), Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University , Shanghai 200433, China.
Journal of the American Chemical Society
|January 16, 2018
まとめ
研究者は,人工的な水分裂のための新しい,高度に活性な酸化マンガン (MnOx) 触媒を特定しました. 自然の光システムIIを模倣した特定の欠陥マンガンの部位は,酸素進化反応 (OER) の効率を大幅に高めます.
科学分野:
- 材料科学
- 電気化学
- キャタリシス
背景:
- マンガンの酸化物 (MnOx) は,天然の光合成を複製することを目的として,人工的な水分裂の触媒として広範に研究されています.
- 酸素進化反応 (OER) の最も活発なMnOx触媒は,しばしばスピネル構造から派生し,in situで δ-MnO2層を形成するが,その活性部位は十分に理解されていない.
- MnOx変換の原子レベルメカニズムを理解し,活性サイトを特定することは,効率的な水分裂触媒の設計に不可欠です.
研究 の 目的:
- 水性電解質におけるスピネルから層への固体相移行の原子レベルメカニズムを解明する.
- MnOx触媒における高いOER活性に責任のある特定の活性部位を特定する.
- 構造上の欠陥が水分解の触媒性能にどのように影響するか理解する.
主な方法:
- ストキャスティック・サーフェス・ウォーキング (SSW) 経路サンプリング法で,固体相変遷メカニズムを調査する.
- 異なるMnOx構造と欠陥部位のOER活動を評価するための第一原理計算.
- Mn溶解,脱位,層変化を含む構造変化の分析
主要な成果:
- スピネルから層への移行は,高電圧で形成される一時的なH0.5MnO2相を経由して進みます.
- この移行により,MnOx構造の欠陥が生じ,Mnの空白がある構造も含まれます.
- 隣接するMn空白の特定のエッジサイトは",片隅が欠けている偽キューバン"構造を持ち,0.59Vの低い超電位で優れたOER活動を示しています.
結論:
- MnOx触媒の高いOER活動は,欠陥のあるサイト,特にMnの空白があるサイトから発生し,中間吸収を高めます.
- 特定された活性サイト構造は,自然の光システムII (PSII) の触媒中心と類似しています.
- この研究は,効率的な人工水分裂のためのMnOx触媒設計に関する原子レベルの洞察を提供します.
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