Kinetic modeling of electrocatalytic oxygen reduction products from lipid-modified electrodes

Abstract

O2 reduction can occur via 1e−, 2e−, and 4e− pathways to yield O2−, H2O2, and H2O, respectively. Experimentally, it is often difficult to distinguish between the 1e− and 2e− pathways because O2− rapidly disproportionates in acidic and neutral aqueous solutions to H2O2 and O2. In this manuscript, we combine a mathematical model with previous experimental results with O2 reduction electrocatalysts on lipid-modified electrodes. The model demonstrates that for a typical O2 reduction catalyst, the individual rate constants for the 1e−, 2e−, and 4e− pathways can be determined within a fairly narrow range with O2 reduction current and H2O2 production rates as the only experimental inputs. This model will aid electrochemists in assessing the mechanism and selectivity of O2 reduction catalysts.