Oxygen Reduction Reaction Promoted by Manganese Porphyrins
- Harvard Univ., Cambridge, MA (United States); Harvard University
- Harvard Univ., Cambridge, MA (United States)
- Université Paris Diderot (France)
Here, the oxygen reduction reaction (ORR) is catalyzed by manganese(II) porphyrins in the presence of Brønsted acids (HAs). Analyses of the catalytic cyclic voltammetric profiles have permitted the ORR mechanism to be constructed and rate constants to be extracted for both the formation of the initial oxygen adduct and the O–O bond cleavage event for a series of HAs. The dependence of the formation rate constant of the oxygen adduct on reactant concentrations reveals a rate law that is first order in Mn porphyrin and oxygen substrate. A second order dependence in HA is observed for unadorned Mn porphyrin platforms whereas with Mn hangman porphyrin, a proton is provided intramolecular to the oxygen adduct and consequently the HA order is reduced to unity. Lastly, the stabilization of the oxygen adduct with an additional hydrogen bond from HA engenders a rate-determining step involving O–O bond cleavage, resulting in the rare instance where the activation of the O–O bond is directly observed
- Research Organization:
- Harvard Univ., Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
- Grant/Contract Number:
- SC0017619
- OSTI ID:
- 1597470
- Alternate ID(s):
- OSTI ID: 1539513
- Journal Information:
- ACS Catalysis, Journal Name: ACS Catalysis Journal Issue: 9 Vol. 8; ISSN 2155-5435
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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