Theoretical Study of the Electrocatalytic Reduction of Oxygen by Metallocorroles

Metallocorroles are transition metal complexes showing great promise as oxygen reduction reaction catalysts. The performance of metallocorrole catalysts is highly sensitive to the nature of the transition metal employed, although currently this dependence remains elusive. In the current work, we present a first principles density functional theory (DFT) investigation of the oxygen reduction reaction mechanism in acidic media using several first-row transition metal corroles. We show that the identity of the metal center, M, determines the relative formation free energies of the reaction intermediates, and thus the potential-determining step in the four-electron reduction process directly to water. For M═Mn, Fe, and Co, the hydroperoxyl intermediate is a thermodynamic maximum along the reaction path, whereas for Ni and Cu, the formation of the hydroperoxyl intermediate is a thermodynamic trap, with the following oxo intermediate being highly unstable. The formation of the oxo intermediate was carefully inv...