アモルフなコバルト酸化物触媒の酸素変化性能の基礎となる電子的および構造的要因の解像度
Gihan Kwon, Hoyoung Jang1, Jun-Sik Lee1
1Stanford Synchrotron Radiation Light Source , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States.
Journal of the American Chemical Society
|July 21, 2018
まとめ
アモルフなコバルト酸化物膜 (CoBiとCoPi) は,異なる電荷輸送特性により,異なる酸素進化反応 (OER) 性能を示す. 調整と結合を含む構造的および電子的差異は,高度なX線技術を使用して特定されました.
科学分野:
- 材料科学
- 電気化学
- キャタリシス
背景:
- 非貴金属の薄膜酸化物は,酸素進化反応 (OER) の重要な触媒である.
- コバルトボラート (CoBi) やコバルトフォスファート (CoPi) などの無形コバルト酸化物は,電子-陽子輸送に関連した異なるOER性能を示す.
- 基本的な電子的および構造的な違いを理解することは,OER触媒を最適化するための鍵です.
研究 の 目的:
- CoBi と CoPi の薄膜の異なるOER性能を制御する電子的および構造的要因を明らかにする.
- これらのコバルト酸化物における特定の構造モチーフと電子ハイブリッド化との相関性を調べる.
主な方法:
- LエッジX線吸収 (XAS),共振X線放射 (RXES),共振不弾性X線散射 (RIXS),共振ラマン (RR) 散射,および高エネルギーX線ペア分布関数 (PDF) 解析など,高度なX線技術を用いた.
- コバルトの調整,電子ハイブリッド化,およびCoBiとCoPiのフィルムの構造的順序を調査した.
主要な成果:
- CoBiフィルムは主に八面体コバルトを含み,CoPiは八面体コバルトと共に17%の四面体Co (II) を含んでいる.
- 酸素媒介のCo-O-Co p-dハイブリデーションとインターサイトDD刺激は,CoBiでは観察されたが,CoPiでは観察されなかった.
- CoBiは乱雑な層状のLiCoO2のような構造を示し,CoPiは無形であり,それぞれに異なるナノメートルスケールのドメインモデルが提案されています.
結論:
- CoBi と CoPi の間には大きな電子的および構造的差異があり,それらのOERの触媒効率に直接影響します.
- CoBiにおける四面体コバルト,特定のCo-O-Co結合,およびオーダードメインの存在は,OERの性能の向上に貢献する.
- これらの発見は,酸素進化反応のための優れた非貴金属酸化物触媒の設計に重要な洞察を提供します.
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