Oxygen Reduction Reaction (ORR) Activity of a Phenol‐Substituted Linear Fe III –Porphyrin Dimer

We report oxygen reduction reaction (ORR) activity in a phenol‐substituted iron porphyrin dimer used as catalyst. Supported on carbon, Fe III –porphyrin dimer FeDOH /C shows about 60 mV higher onset potential (OP) and about 50 mV higher half‐wave potential (HWP) than those of the unsubstituted monomer ( FeM /C). When these two catalysts are compared with the phenol‐substituted monomer catalyst ( FeMOH /C), the improvement in the OP and HWP values for FeDOH /C with respect to those of FeM /C and FeMOH /C are attributed to its phenol group under acidic conditions and to the proximity of two active iron centers coordinated by four nitrogen ligands.