Fe–N–carbon black for the oxygen reduction reaction in sulfuric acid Original Research Article

A Fe–N–C catalyst was prepared by pyrolyzing carbon black supported Fe–imidazole complexes. The effect of different pyrolysis temperatures on the catalysts’ oxygen reduction reaction (ORR) activity was investigated by electrochemical rotating disk electrode tests in 0.5 M H2SO4. The Fe–N–C catalyst heat-treated at 700 °C was found to display the best ORR activity with a highest half-wave potential of 0.656 V vs. normal hydrogen electrode (NHE), which was only 64 mV lower than that of the commercial Pt–C (loading: 10 μgPt cm−2), and a lowest H2O2 yield (0.6% at 0.4 V vs. NHE). Furthermore, potential cycling tests showed that the catalyst had a better electrochemical stability than Pt–C catalyst. X-ray photoelectron spectroscopy characterization of these catalysts was also conducted to identify the active nitrogen species for ORR.