Tracking Minority Species in Redox Reactions: A Quantitative Combined XAS and Modulation Excitation Study

Armando Ibraliu, Xiaolei Fan, Luke Keenan, Tathiana M. Kokumai, Matteo Aramini, Veronica Celorrio, Adam J. Greer, Daniel T. Bowron, Christopher Hardacre, Sofia Diaz-Moreno

Research output: Journal PublicationArticlepeer-review

Abstract

Understanding the nature of intermediates/active species in reactions is a major challenge in chemistry. This is because spectator species typically dominate the experimentally derived data and consequently active phase contributions are masked. Transient methods offer a means to bypass this difficulty. In particular, modulation excitation with phase-sensitive detection (ME-PSD) provides a mechanism to distinguish between spectator and reacting species. Herein, modulation excitation (ME) time-resolved (energy dispersive) X-ray absorption spectroscopy, assisted by phase sensitive detection (PSD) analysis, has been applied to the study of a liquid phase process; in this case the classic ferrocyanide/ferricyanide redox couple. Periodic switches of the electrical potential (anodic/cathodic) enabled the use of the ME approach. Structural changes at fractions as low as 2 % of the total number of electroactive species were detected within the X-ray beam probe volume containing ~30 pmol of Fe(II)/Fe(III).

Original languageEnglish
Article numbere202401888
JournalAngewandte Chemie - International Edition
Volume63
Issue number47
DOIs
Publication statusPublished - 18 Nov 2024
Externally publishedYes

Keywords

  • electrochemistry
  • EXAFS
  • hexacyanoferrate
  • modulation excitation
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry

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