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鉄化合物からFe1(II) -N4への進化経路 溶解中のガス相鉄を通過する場所
Jingkun Li1, Li Jiao, Evan Wegener2
1Institut Charles Gerhardt Montpellier, UMR 5253, CNRS , Université Montpellier, ENSCM , Place Eugène Bataillon , 34095 Montpellier cedex 5 , France.
Journal of the American Chemical Society
|December 28, 2019
まとめ
ピロリシスは,鉄の前駆体を,酸素還元反応 (ORR) の単原子Fe1(II) -N4サイトに変換する. この研究は,高度に活性なFe-N-C触媒を作るための蒸気相輸送機構を明らかにしています.
科学分野:
- 材料科学
- 電気化学
- キャタリシス
背景:
- 酸化反応は,酸性環境における酸素還元反応 (ORR) のための鉄-窒素-炭素 (Fe-N-C) 触媒の合成に不可欠である.
- 熱分解中にFe,N,Cの前駆体が活性ORRサイトに変換される正確な経路はよく理解されていません.
- この知識のギャップはFe-N-C触媒の合理的な設計と最適化を妨げています.
研究 の 目的:
- Fe-N-C触媒の酸化過程で,前駆体からORR活性部位への進化経路を解明する.
- 形成された活性部位の特定の原子構造を特定する.
- FeをN-ドーピングされた炭素マトリックスに組み込むメカニズムを理解する.
主な方法:
- 溶解中の変異を監視するために,in-situ温度解像度X線吸収スペクトロスコーピー (XAS) を使用した.
- 異なる温度で形成された中間種と最終種の特徴.
- 提案されたメカニズムを非接触式溶解法で検証する.
主要な成果:
- 鉄の前駆体は,最初に300°C以下で酸化鉄を形成する.
- 結晶を溶かすような変換は600°C以下で四面体Fe1(II) -O4サイトにつながる.
- 600 °C以上では,Fe1(II) -O4は単一のFe原子を放出し,N-ドーピングされた炭素欠陥に拡散し,Fe1(II) -N4サイトを蒸気相輸送機構で形成します.
結論:
- この研究は,Fe1(II) -N4活性部位の形成のための独特の蒸気相単一のFe原子輸送機構を明らかにしています.
- この理解は,Fe-N-C触媒合成における前駆体-産物関係を明確にする.
- 発見は,ORRのための高度に活性で選択的なFe-N-C触媒の合理的な設計のための経路を提供します.
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