酸素進化反応のダイナミクス,ファラダイク電荷効率,およびNi-Fe酸化水分解電解剤の活性金属レドックス状態
Mikaela Görlin1, Petko Chernev2, Jorge Ferreira de Araújo1
1Technical University Berlin , Department of Chemistry, Chemical Engineering Division, Straße des 17. Juni 124, 10623 Berlin, Germany.
Journal of the American Chemical Society
|April 1, 2016
まとめ
この研究は,水分裂中のニッケル鉄触媒の酸化状態を明らかにする. 混合Ni-Fe触媒は酸素進化反応の効率を高め,ニッケルが重要な役割を果たしています.
科学分野:
- 電気化学
- 材料科学
- カタリシス
背景:
- 混合ニッケル鉄 (Ni-Fe) オキシドは,太陽光燃料生産における水分解のための有望なアノド触媒です.
- 以前の研究では,酸素進化反応 (OER) 中のこれらの触媒の活性酸化還元状態に関する矛盾した結果が報告された.
研究 の 目的:
- オペランド条件下で,Ni-FeオキシヒドロキシドOER触媒におけるNiとFeの酸化還元状態を定量的に決定する.
- これらの触媒における酸素進化反応のダイナミクスと個々のファラダイク効率を解明する.
主な方法:
- オペランド微分電気化学質量スペクトロメトリー (DEMS) を用いて,OERの動態とファラダイク効率を分析する.
- 酸化状態と局所構造を評価するために,NiとFeKのエッジでX線吸収スペクトロスコーピー (XAS) を操作する.
主要な成果:
- NiOOH触媒では,Niの酸化状態が+3 (最大75%),+4 (最大25%) に増加し,Feは+3にとどまった.
- >9原子%のFeを持つ混合Ni-Fe触媒は,O2のファラダイム効率が30%から90%まで急激に増加し,Niは主に+2にとどまったことを示唆した.
- O2 の放出中に金属の酸化と還元の間の動的競争が,高値の Ni 状態の低蓄積を説明すると仮定された.
結論:
- Ni-FeオキシヒドロキシドOER触媒の活性酸化還元状態は複雑で,組成と反応条件に依存する.
- 表面触媒またはリドックス無活性金属に焦点を当てた単純なモデルは,高度に活性なNi-Feサイトにおけるシネージ効果を過度に単純化します.
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