从铁化合物到Fe1(II) -N4的进化途径 在热解过程中通过气相铁
Jingkun Li1, Li Jiao, Evan Wegener2
1Institut Charles Gerhardt Montpellier, UMR 5253, CNRS , Université Montpellier, ENSCM , Place Eugène Bataillon , 34095 Montpellier cedex 5 , France.
Journal of the American Chemical Society
|December 28, 2019
概括
热解将铁前体转化为氧降解反应 (ORR) 催化剂的单原子Fe1-N4位点. 这项研究揭示了制造高活性Fe-N-C催化剂的蒸汽相运输机制.
科学领域:
- 材料科学
- 电化学
- 催化剂
背景情况:
- 热解对于在酸性介质中合成氧降解反应 (ORR) 的铁--碳 (Fe-N-C) 催化剂至关重要.
- 在热解过程中,Fe,N和C前体的精确转化途径未被充分理解.
- 这种知识差距阻碍了Fe-N-C催化剂的合理设计和优化.
研究的目的:
- 在Fe-N-C催化剂的热解过程中阐明前体进入ORR活性位点的演化途径.
- 确定形成的活性位点的特定原子结构.
- 了解融入N-化碳矩阵的机制.
主要方法:
- 使用现场温度分辨率的X射线吸收光谱 (XAS) 来监测热解过程中的变化.
- 在不同温度下形成的中间和最终物种的特征.
- 使用非接触式热解方法验证拟议的机制.
主要成果:
- 铁前体最初在300°C以下形成铁氧化物.
- 一种类似于水晶融化的转化导致600°C以下的四面体Fe1
- 在600°C以上,Fe1(II) -O4会释放单个Fe原子,这些Fe1(II) -N4原子通过蒸汽相传输机制扩散到N-化碳缺陷中.
结论:
- 这项研究揭示了形成Fe1(II) -N4活性位点的独特蒸汽相单原子运输机制.
- 这种理解澄清了Fe-N-C催化剂合成中的前体与产物关系.
- 这些发现为ORR的高活性和选择性Fe-N-C催化剂的合理设计提供了途径.
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