Oxygen Reduction Catalysis at a Dicobalt Center: The Relationship of Faradaic Efficiency to Overpotential
Department
of Chemistry and
Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/jacs.5b12828
Abstract
The selective four electron, four proton, electrochemical reduction of O2 to H2O
in the presence of a strong acid (TFA) is catalyzed at a dicobalt
center. The faradaic efficiency of the oxygen reduction reaction (ORR)
is furnished from a systematic electrochemical study by using rotating
ring disk electrode (RRDE) methods over a wide potential range. We
derive a thermodynamic cycle that gives access to the standard potential
of O2 reduction to H2O in organic solvents, taking into account the presence of an exogenous proton donor. The difference in ORR selectivity for H2O vs H2O2 depends on the thermodynamic standard potential as dictated by the pKa of the proton donor. The model is general and rationalizes the faradaic efficiencies reported for many ORR catalytic systems.
コメント