多级计算研究揭示了轴联体对Fe-N-C材料氧降解反应的重要性
Phillips Hutchison1, Peter S Rice2, Robert E Warburton1
1Department of Chemistry, Yale University, New Haven, Connecticut06520, United States.
Journal of the American Chemical Society
|August 24, 2022
概括
了解燃料电池中的氧降解反应 (ORR) 需要详细的原子学见解. 这项研究表明,一个特定的铁水复合体对于Fe-N-C材料的高效ORR催化是至关重要的.
科学领域:
- 电化学
- 材料科学
- 计算化学
背景情况:
- Fe-N-C 材料是燃料电池的有希望的催化剂,但它们的性能由于对原子级氧降解反应 (ORR) 的不完全理解而受到限制.
- 需要精确的原子模型来阐明在电化学条件下控制这些材料ORR的复杂质子合电子转移 (PCET) 过程.
研究的目的:
- 在Fe-N-C电催化剂上计算氧降解反应 (ORR) 的机制和热力学.
- 确定控制ORR运动的关键中间体和速度限制步骤.
- 确定活性位结构和溶剂相互作用在ORR催化中的作用.
主要方法:
- 采用了多层计算方法,结合了初始分子动力学 (AIMD) 和恒定电位密度函数理论 (DFT) 的计算.
- 评估了关键ORR中间体的质子合电子转移 (PCET) 过程和吸附热力学.
- 采用了一个主动位点模型,其中包含一个与铁中心轴联的水分子.
主要成果:
- 确定了FeIII-OOH中间体的形成作为Fe-N-C材料上ORR的潜在限制步骤.
- 证明了一个带有轴坐标的水分子的活性位点模型准确地预测了实验ORR开始和Fe (III/II) 氧化还原潜力.
- 显示一个五坐标活点,而不是一个四坐标活点,显著影响ORR热力学和机制.
结论:
- 轴联水分子的存在对于精确建模Fe-N-C催化剂的ORR机制和电化学性能至关重要.
- 在现实的电化学条件下,溶剂-基质相互作用和表面电荷效应在PCET机制和过渡金属氧化还原对中发挥着关键作用.
- 这些发现为燃料电池应用的Fe-N-C电催化剂的合理设计和优化提供了关键的原子学见解.
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