Operando Characterization of Iron Phthalocyanine Deactivation during Oxygen Reduction Reaction Using Electrochemical Tip-Enhanced Raman Spectroscopy

Zhu Chen, Song Jiang, Gyeongwon Kang, Duc Nguyen, George C. Schatz, Richard P. Van Duyne

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)15684-15692
Number of pages9
JournalJournal of the American Chemical Society
Volume141
Issue number39
DOIs
Publication statusPublished - Oct 2 2019

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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