多層計算研究により,Fe-N-C材料における酸素還元反応における軸性リガンドの重要性が明らかになった
Phillips Hutchison1, Peter S Rice2, Robert E Warburton1
1Department of Chemistry, Yale University, New Haven, Connecticut06520, United States.
Journal of the American Chemical Society
|August 24, 2022
まとめ
燃料電池における酸素還元反応 (ORR) を理解するには,詳細な原子学的洞察が必要です. この研究は,Fe-N-C材料の効率的なORR触媒に特定の鉄水複合体が不可欠であることを明らかにしています.
科学分野:
- 電気化学
- 材料科学
- コンピュータ化学
背景:
- Fe-N-C材料は燃料電池の有望な触媒ですが,その性能は原子レベルで酸素還元反応 (ORR) の不完全な理解によって制限されています.
- これらの物質の電気化学的条件下でORRを制御する複雑な陽子結合電子伝送 (PCET) プロセスを解明するには,正確な原子モデルが必要です.
研究 の 目的:
- Fe-N-C電触媒における酸素還元反応 (ORR) のメカニズムと熱力学を計算的に調査する.
- ORR運動を制御する主要な中間物質と速度制限ステップを特定する.
- ORR触媒における活性部位構造と溶媒の相互作用の役割を決定する.
主な方法:
- 初期分子ダイナミクス (AIMD) と定数ポテンシャル密度関数理論 (DFT) の計算を組み合わせた多層計算アプローチを採用した.
- 評価された陽子結合電子伝送 (PCET) プロセスと重要なORR中間物の吸附熱力学.
- 鉄の中心に軸に結合した水分子を特徴とするアクティブサイトモデルを使用した.
主要な成果:
- FeIII-OOH 中間物質の形成は,Fe-N-C 材料のORRの潜在的制限段階として特定された.
- 軸に調整された水分子を備えた活性サイトモデルは,実験的なORR発生とFe (III/II) 還酸化ポテンシャルを正確に予測することを実証した.
- 4つの座標よりも5つの座標の活性サイトが ORRの熱力学とメカニズムに大きく影響することを示した.
結論:
- Fe-N-C触媒のORRメカニズムと電気化学的性能を正確にモデル化するために,軸に結合した水分子の存在は不可欠です.
- 溶媒と基板の相互作用と表面電荷効果は,現実的な電気化学的条件下で,PCETメカニズムと移行金属リドックスカップルにおいて重要な役割を果たします.
- これらの発見は,燃料電池アプリケーションのためのFe-N-C電解剤の合理的な設計と最適化のための重要な原子学的洞察を提供します.
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