Operando Characterization of Iron Phthalocyanine Deactivation during Oxygen Reduction Reaction Using Electrochemical Tip-Enhanced Raman Spectroscopy
Operando Characterization of Iron Phthalocyanine Deactivation during Oxygen Reduction Reaction Using Electrochemical Tip-Enhanced Raman Spectroscopy
复制标题
DOI：
10.1021/jacs.9b07979
复制
发表时间：
2019-10-02
影响因子：
15
通讯作者：
Van Duyne, Richard P.
中科院分区：
文献类型：
--
作者：
Chen, Zhu;Jiang, Song;Van Duyne, Richard P.
利用电化学针尖增强拉曼光谱（EC-TERS）研究了氧还原反应（ORR）模型催化剂酞菁铁（FePc）的结构和活性。使用EC-TERS，在ORR过程中观察到FePc的可逆变化和不可逆降解。FePc的拉曼光谱中的可逆变化可以与FePc分子在催化过程中适应非平面几何形状有关。相反，FePc的不可逆降解是FePc脱金属的结果，导致随后形成游离碱酞菁。这一观察结果证实，在ORR过程中，FePc脱金属通过Fe 2+的直接损失进行，并且碳腐蚀不是操作机制。重要的是，FePc脱金属过程可以与ORR活性的损失相关，这表明含Fe位点对于FePc实现高催化活性是必不可少的。这项研究建立了EC-TERS作为一个很有前途的技术，在分子尺度上的电催化反应的操作表征。
Electrochemical tip-enhanced Raman spectroscopy (EC-TERS) has been implemented to investigate the structure and activity of iron(II) phthalocyanine (FePc)-a model catalyst for the oxygen reduction reaction (ORR). Using EC-TERS, both reversible change and irreversible degradation to FePc have been observed during ORR The reversible change in the Raman spectrum of FePc can be related to the FePc molecules that adapt a nonplanar geometry during catalysis. In contrast, the irreversible degradation of FePc is a consequence of FePc demetalation, leading to the subsequent formation of free base phthalocyanine. This observation affirms that FePc demetalation during ORR proceeds via a direct loss of Fe2+ and that carbon corrosion is not the operative mechanism. Importantly, the FePc demetalation process can be correlated with a loss of ORR activity suggesting that Fe-containing sites are essential for FePc to achieve high catalytic activity. This study establishes EC-TERS as a promising technique for the operando characterization of electrocatalytic reactions at the molecular scale.