電気化学的酸素還元による過酸化水素の選択的生産の起源
1Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
Journal of the American Chemical Society
|June 16, 2021
まとめ
研究 者 たち は,酸素 還元 反応 (ORR) の 過程 で 触媒 が 酸化 水素 の 生成 を 促進 する 理由 を 発見 し まし た. 陽子の親和性は,電位とpHの影響で,選択性を決定し,実験的観測を説明しています.
科学分野:
- 電気化学
- 材料科学
- コンピュータ化学
背景:
- 酸素還元反応 (ORR) は電気化学において極めて重要であり, *-O-OH 中間物質からの2つの経路:過酸化水素 (H2O2) または水形成である.
- 既存の触媒は,熱力学的な予測に反して,しばしば高いH2O2選択性を示し,この選択性は潜在力とpHによって変化し,明確な説明がない.
研究 の 目的:
- 固体と水の界面における電気化学反応運動を計算するための高度な第一原理モデルを開発する.
- H2O2の選択性を支配する基本的なメカニズム,特にポテンシャルとpHの影響を明らかにする.
主な方法:
- 電気化学反応の運動をシミュレートするために,高度な第一原理の計算モデルを開発し,適用した.
- H2O2の生成のための反応経路とエネルギーバリアを調査した.
主要な成果:
- O-OH結合の断絶は,結合の剛性により*-O結合の断絶よりも高いエネルギーバリアを有することが確認された.
- *-O-OH中間の酸素原子に対する陽子の親和性が,電位とpHの選択性依存を決定する重要な要因であることが明らかになった.
- 単一コバルト原子と炭素触媒の異なる陽子吸収行動を示し,異なる条件下での異なるH2O2選択性を説明した.
結論:
- 陽子の親和は,ORRの選択性を制御する,これまで認識されていない重要な要因です.
- 開発されたモデルは,実験的なH2O2の選択性と外部要因への依存を正確に説明しています.
- この研究はORR運動の理解を深め,異質電気化学のための新しい計算ツールを提供します.
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