Oxygen Isotopologues Resolved from Water Oxidation Electrocatalysis by Electron Paramagnetic Resonance Spectroscopy

Trisha T. Nguyen, Richard I. Sayler, Aaron H. Shoemaker, Jibo Zhang, Stefan Stoll, Jay R. Winkler, R. David Britt*, Bryan M. Hunter*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Electrocatalytic water oxidation is a key transformation in many strategies designed to harness solar energy and store it as chemical fuels. Understanding the mechanism(s) of the best electrocatalysts for water oxidation has been a fundamental chemical challenge for decades. Here, we quantitate evolved dioxygen isotopologue composition via gas-phase EPR spectroscopy to elucidate the mechanisms of water oxidation on metal oxide electrocatalysts with high precision. Isotope fractionation is paired with computational and kinetic modeling, showing that this technique is sensitive enough to differentiate O-O bond-forming steps. Strong agreement between experiment and theory indicates that for the nickel-iron layered double hydroxide─one of the best earth-abundant electrocatalysts to be studied─water oxidation proceeds via a dioxo coupling mechanism to form a side-bound peroxide rather than a hydroxide attack to form an end-bound peroxide.

Original languageEnglish (US)
Pages (from-to)15019-15026
Number of pages8
JournalJournal of the American Chemical Society
Volume146
Issue number22
DOIs
StatePublished - Jun 5 2024

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry

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