无形氧催化剂的氧变性性能基础的电子和结构因素的分辨率
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
概括
由于具有不同的电荷传输特性,无形氧膜 (CoBi和CoPi) 的氧化演变反应 (OER) 性能不同. 使用先进的X射线技术确定了结构和电子差异,包括协调和粘合.
科学领域:
- 材料科学
- 电化学
- 催化剂
背景情况:
- 非贵金属薄膜氧化物是氧化演化反应 (OER) 的关键催化剂.
- 无形氧化物,如酸 (CoBi) 和酸 (CoPi),表现出与电子-质子传输相关的不同OER性能.
- 了解基本的电子和结构差异是优化OER催化剂的关键.
研究的目的:
- 阐明控制COBi和COPi薄膜不同OER性能的电子和结构因素.
- 将这些氧化物中的电荷传输特性与特定的结构图案和电子杂交联系起来.
主要方法:
- 使用了一套先进的X射线技术:L边缘X射线吸收 (XAS),共振X射线发射 (RXES),共振无弹性X射线散射 (RIXS),共振拉曼 (RR) 散射和高能X射线对分布函数 (PDF) 分析.
- 研究了Cobi和Copi膜中的协调,电子杂交和结构排序.
主要成果:
- CoBi薄膜主要含有八面体,而CoPi含有约17%的四面体和八面体.
- 在 CoBi 中观察到氧介导的 Co-O-Co p-d 杂交和位点间的 dd 激发,但没有 CoPi.
- CoBi 呈现出一种无序的层状LiCoO2 结构,而 CoPi 是无形的,对于每一种都提出了不同的纳米级域模型.
结论:
- CoBi和CoPi之间存在显著的电子和结构差异,这直接影响了它们的开放式催化效率.
- 在CoBi中存在四面体,特定的Co-O-Co结合和有序域,有助于提高OER性能.
- 这些发现为设计氧化反应的优质非贵金属氧化物催化剂提供了关键的见解.
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