Standard Reduction Potentials for Oxygen and Carbon Dioxide Couples in Acetonitrile and N,N-Dimethylformamide

Michael L. Pegis, John Roberts, Derek J. Wasylenko, Elizabeth A. Mader, Aaron Appel, James M. Mayer

Research output: Contribution to journalArticle

87 Citations (Scopus)

Abstract

A variety of next-generation energy processes utilize the electrochemical interconversions of dioxygen and water as the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Reported here are the first estimates of the standard reduction potential of the O2 + 4e- + 4H+ ⇋ 2H2O couple in organic solvents. The values are +1.21 V in acetonitrile (MeCN) and +0.60 V in N,N-dimethylformamide (DMF), each versus the ferrocenium/ferrocene couple (Fc+/0) in the respective solvent (as are all of the potentials reported here). The potentials have been determined using a thermochemical cycle that combines the free energy for transferring water from aqueous solution to organic solvent, -0.43 kcal mol-1 for MeCN and -1.47 kcal mol-1 for DMF, and the potential of the H+/H2 couple, - 0.028 V in MeCN and -0.662 V in DMF. The H+/H2 couple in DMF has been directly measured electrochemically using the previously reported procedure for the MeCN value. The thermochemical approach used for the O2/H2O couple has been extended to the CO2/CO and CO2/CH4 couples to give values of -0.12 and +0.15 V in MeCN and -0.73 and -0.48 V in DMF, respectively. Extensions to other reduction potentials are discussed. Additionally, the free energy for transfer of protons from water to organic solvent is estimated as +14 kcal mol-1 for acetonitrile and +0.6 kcal mol-1 for DMF.

Original languageEnglish
Pages (from-to)11883-11888
Number of pages6
JournalInorganic Chemistry
Volume54
Issue number24
DOIs
Publication statusPublished - Dec 7 2015

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

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