There remain great challenges in exploring cost-effective and highly efficient non-noble metal electrocatalysts to catalyze the oxygen reduction reaction (ORR) of proton exchange membrane fuel cells (PEMFCs). Also, a further validation on their performances under a fuel cell operating condition draws sustained attention. Herein, we report a comprehensive investigation on the ORR performances of a series of pyrolyzed Fe-N-C composites that use phenanthrolene as the nitrogen precursor, and the effects of carbon supports, transition metal precursors, and annealing temperatures are examined in detail. Electrochemical measurements combined with different physicochemical characterizations are employed to clarify the function of critical structures including the specific surface area, microstructure, nitrogen content, nitrogen type, and corresponding proportion on their ORR and fuel cell performances. It demonstrates a half-wave potential of 0.79 V and almost a four-electron pathway. When using the as-optimized Fe-N-C composite as the cathode catalyst of a PEMFC, the maximum power density reaches as high as 540 mW cm-2.
Keywords: Fe−N−C; annealing temperature; non-noble metal electrocatalyst; oxygen reduction reaction; phenanthrolene as a nitrogen precursor.