Reactivity Descriptors for the Activity of Molecular MN4 Catalysts for the Oxygen Reduction Reaction

Abstract Similarities are established between well‐known reactivity descriptors of metal electrodes for their activity in the oxygen reduction reaction (ORR) and the reactivity of molecular catalysts, in particular macrocyclic MN4 metal complexes confined to electrode surfaces. We show that there is a correlation between the M III /M II redox potential of MN4 chelates and the M‐O 2 binding energies. Specifically, the binding energy of O 2 (and other O species) follows the M III ‐OH/M II redox transition for MnN4 and FeN4 chelates. The ORR volcano plot for MN4 catalysts is similar to that for metal catalysts: catalysts on the weak binding side (mostly CoN4 chelates) yield mainly H 2 O 2 as the product, with an…