Electrocatalytic oxygen reduction with cobalt corroles bearing cationic substituents.

Recent decades have seen increasing interest in developing highly active and selective electrocatalysts for the oxygen reduction reaction (ORR). The active site environment of cytochrome oxidases (COs), including electrostatic and hydrogen-bonding interactions, plays an important role in promoting the selective conversion of dioxygen to water. Herein, we report the synthesis of three Co corroles, namely 1 (with a 10-phenyl -trimethylammonium cationic group), 2 (with a 10-phenyl -dimethylamine group) and 3 (with a 10-phenyl -trimethylammonium cationic group) as well as their electrocatalytic ORR activities in both acidic and neutral solutions. We discovered that 1 is much more active and selective than 2 and 3 for the electrocatalytic four-electron ORR. Importantly, 1 showed ORR activities with half-wave potentials at = 0.75 V RHE in 0.5 M HSO solutions and at = 0.70 V RHE in neutral 0.1 M phosphate buffer solutions. This work is significant for outlining a strategy to increase both the activity and selectivity of metal corroles for the electrocatalytic ORR by introducing cationic units.