Molecular catalysis of the oxygen reduction reaction by iron porphyrin catalysts tethered into Nafion layers: An electrochemical study in solution and a membrane-electrode-assembly study in fuel cells

► There exists ionic interaction between sulfonic groups of Nafion and FeTMPyP. ► The half wave potential value (E1/2) for FeTMPyP was positively shifted by modifying the electrode with Nafion. ► Fuel cell molecular catalysis system has been demonstrated to be working based on a FeTMPyP + Nafion ionomer-coated cathode.