Ligand effects on the overpotential for dioxygen reduction by tris(2-pyridylmethyl)amine derivatives

Matthew A. Thorseth, Christopher S. Letko, Edmund C.M. Tse, Thomas B. Rauchfuss, Andrew A. Gewirth

Research output: Contribution to journalArticlepeer-review

Abstract

A series of copper complexes based on the tris(2-pyridylmethyl)amine (TPA) ligand are examined for their oxygen reduction reaction (ORR) activity. Increasing the potential of the CuI/II couple from 0.23 V vs RHE for [Cu(TPA)(L)]2+ to 0.52 V for [Cu(TEPA)(L)]2+ (tris(2-pyridylethyl)amine) at pH 7 or adding a hydrogen-bonding secondary coordination sphere does not increase the onset potential from 0.69 V vs RHE for the ORR. The underlying mechanism for the ORR is determined to be first-order in O2 and second-order in Cu. The rate-determining step is found to not be CuII to CuI reduction, as seen in other systems. The rate-determining step is also not the protonation of an intermediate, but may be the reduction of a hydroperoxo intermediate. Pyrolysis of the Cu complex of TPA affords an inactive material; activity is recovered through addition of intact TPA to the electrode surface.

Original languageEnglish (US)
Pages (from-to)628-634
Number of pages7
JournalInorganic Chemistry
Volume52
Issue number2
DOIs
StatePublished - Jan 18 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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