高性能のPGMフリーORR触媒の活性部位への直接的な原子レベルの洞察
Hoon T Chung1, David A Cullen2, Drew Higgins1
1Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
まとめ
プラチナ系無金属触媒は燃料電池の安価な代替品です この研究は,鉄-窒素-炭素触媒が,水素-空気燃料電池のプラチナに匹敵する性能を達成することを示しています.
科学分野:
- 電気化学
- 材料科学
- カタリシス
背景:
- ポリマー電解質燃料電池 (PEFC) のコストを削減するために,プラチナグループ無金属 (PGMフリー) 触媒は不可欠です.
- 主要な課題は,酸素還元反応 (ORR) の活性部位を特定し,自動車条件下で水素空気燃料電池の競争力のある性能を達成することです.
研究 の 目的:
- 鉄-窒素-炭素触媒を用いた水素-空気燃料電池の性能向上を実証する.
- 酸素還元反応を起こす触媒活性部位を特定し視覚化する.
主な方法:
- 二つの窒素前駆体を使用した鉄-窒素-炭素触媒の合成により,階層的な多孔性が生じます.
- 水素-空気燃料電池の性能評価,プラチナカソッドとの電流密度を比較する.
- 偏差修正スキャニング伝送電子顕微鏡を使用して,提案された触媒活性部位 (FeN4) の直接視覚化.
- アクティブサイトと炭素構造との関係の計算式探査
主要な成果:
- 合成された鉄・窒素・炭素触媒は,運動領域 (電圧>0.75V) で0.1 mg Pt/cm2の負荷でプラチナカソッドに匹敵する性能を示した.
- 炭素に埋め込まれた窒素調整鉄 (FeN4) の活性部位を直接視覚化しました.
- 計算分析により,活性部位に関連した特定の炭素構造の役割に関する洞察が得られました.
結論:
- 階層的な多孔性を持つ鉄-窒素-炭素触媒は,プラチナベースの触媒と競合するPEFCで競争力のある性能を達成することができます.
- 直接視覚化と計算分析により,FeN4が酸素還元反応の重要な活性成分であることを確認した.
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