解读Fe-N-C催化剂中的潜在驱动动力学:关于Fe-N切换和旋转状态过渡的初步见解
Haobo Li1,2, Fubo Tian2, Zhiyao Duan1
1State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University Xi'an Shaanxi Province 710072 P. R. China zhiyao.duan@nwpu.edu.cn.
Chemical science
|July 24, 2025
概括
化Fe-N-C催化剂在pyridinic FeN4活性位点中显示潜在驱动的Fe-N切换. 这种由旋转状态转换驱动的动态行为,澄清了催化剂结构,并有助于设计更好的氧降解反应 (ORR) 催化剂.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 计算化学计算化学
背景情况:
- 氧化铁碳 (Fe-N-C) 材料是酸氧还原反应 (ORR) 的有希望,具有成本效益的替代品.
- 在Fe-N-C催化剂中的活性位点的精确原子和电子结构仍然不明,这阻碍了合理的设计.
- 实验研究表明,D1型活性中心的Fe-N切换是潜在诱导的,但潜在的机制是难以捉摸的.
研究的目的:
- 阐明Fe-N-C在电化学潜力下的活性位点的原子和电子结构动态.
- 研究D1型遗址中实验观察到的潜在诱导的Fe-N切换背后的机制.
- 为设计先进的基于Fe的ORR催化剂提供理论基础.
主要方法:
- 使用恒定电位*ab initio*分子动力学 (CP-AIMD) 模拟,在不同电化学电位下建模Fe-N-C活性位点.
- 分析了自旋状态转换及其对原子配置的影响.
- 进行了X射线吸收和Mössbauer光谱的计算,以与实验数据进行比较.
主要成果:
- CP-AIMD揭示了0.8V的平面OH*-Fe3+N4和0.8V的外平面H2O*-Fe2+N4配置之间的可逆过渡,用于pyridinic FeN4位点.
- 这种切换是由潜在的下降驱动的,导致中间旋转Fe3+向高旋转Fe2+的过渡,受伪Jahn-Teller效应和H2O结合的影响.
- 一个转移稳定的2H2O*-Fe2.5+N4配置被确定为一个过渡状态. 计算出的光谱与实验结果密切匹配.
- 动态Fe-N切换被发现是pyridinic FeN4位点的独特特征,而不是pyrrolic FeN4位点.
结论:
- 基FeN4位点表现出动态的,潜在驱动的结构切换,澄清了D1型活性中心的性质.
- 这些发现挑战了关于D1遗址结构的先前假设.
- 这项工作为Fe-N-C催化剂的活性位结构和动态提供了关键的见解,为改进ORR催化剂设计铺平了道路.
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