Electropolymerization of Metallo-Corroles: Formation of Highly Active Three-Dimensional Catalysts for Oxygen Reduction

Abstract

Within the class of precious group metal-free (PGM-free) catalysts for oxygen reduction reaction (ORR), significant progress has recently been reported for 1 st row transition metal complexes of corroles , which generally shows better catalytic activity when compared to other molecular, macrocyclic transition metal complexes such as porphyrins and phthalocyanines. In order to further enhance their catalytic activity and durability we recently reported on electropolymerization of Co III corroles. The catalytic activity of the polyCorrole and its monomer for oxygen reduction reaction (ORR) was studied using rotating ring disk electrode (RRDE). The polyCorrole exhibits significantly better catalytic activity than its monomer, reflected in lower overpotential as well as higher selectivity to the desired 4e-/4H+ pathway, both attributed to synergistic biomimetic-like effect of the interconnected catalytic centers. In the current work, we further investigated the polymerization process, trying to determine the parameters influencing the catalytic activity and stability of the polymer, such as morphology, polymerization techniques, chemical environment etc. In addition, the stability of the polyCorroles were measured in order to understand the dominating failure mechanisms which will allows further improvement of the catalyst for application in fuel cells.