Proton transfer dynamics control the mechanism of O2 reduction by a non-precious metal electrocatalyst

Edmund C.M. Tse, Christopher J. Barile, Nicholas A. Kirchschlager, Ying Li, John P. Gewargis, Steven C. Zimmerman, Ali Hosseini, Andrew A. Gewirth

Research output: Contribution to journalArticle

Abstract

Many chemical and biological processes involve the transfer of both protons and electrons. The complex mechanistic details of these proton-coupled electron transfer (PCET) reactions require independent control of both electron and proton transfer. In this report, we make use of lipid-modified electrodes to modulate proton transport to a Cu-based catalyst that facilitates the O2 reduction reaction (ORR), a PCET process important in fuel cells and O2 reduction enzymes. By quantitatively controlling the kinetics of proton transport to the catalyst, we demonstrate that undesired side products such as H2O2 and O2- arise from a mismatch between proton and electron transfer rates. Whereas fast proton kinetics induce H2O2 formation and sluggish proton flux produces O2-, proton transfer rates commensurate with O-O bond breaking rates ensure that only the desired H2O product forms. This fundamental insight aids in the development of a comprehensive framework for understanding the ORR and PCET processes in general.

Original languageEnglish (US)
Pages (from-to)754-759
Number of pages6
JournalNature Materials
Volume15
Issue number7
DOIs
StatePublished - Jul 1 2016

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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