Elucidating Proton Involvement in the Rate-Determining Step for Pt/Pd-Based and Non-Precious-Metal Oxygen Reduction Reaction Catalysts Using the Kinetic Isotope Effect

Edmund C.M. Tse, Jason A. Varnell, Thao T.H. Hoang, Andrew A. Gewirth

Research output: Contribution to journalArticlepeer-review

Abstract

The development of non-precious-metal (NPM) catalysts to replace the Pt alloys currently used in fuel cells to facilitate the oxygen reduction reaction (ORR) is a vital step in the widespread utilization of fuel cells. Currently, the ORR mechanism for NPM catalysts is not well understood, prohibiting the design and preparation of improved NPM catalysts. We conducted a kinetic isotope effect (KIE) study to identify the rate-determining step (RDS) of this intricate electrocatalytic reaction involving multiple proton-coupled electron transfer (PCET) processes. We observed a KIE of about 2 for the ORR catalyzed by a NPM catalyst, which demonstrates that for these electrocatalysts protons are involved in the RDS during ORR. These results contribute to a more complete understanding of the ORR mechanism and suggest that the design of future NPM catalysts must include careful consideration of the role of protons during ORR.

Original languageEnglish (US)
Pages (from-to)3542-3547
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume7
Issue number18
DOIs
StatePublished - Sep 15 2016

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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