Optimizing Surface N-Doping of Fe-N-C Catalysts Derived from Fe/Melamine-Decorated Polyaniline for Oxygen Reduction Electrocatalysis

The insufficient active site density and poor stability of iron and nitrogen co-doped carbon (Fe-N-C) catalyst remain as great challenges for advanced oxygen reduction reaction (ORR). Surface N-doping together with Fe species is considered as an efficient strategy to enhance the catalytic activity and stability of Fe-N-C. Here, we report a facile preparation of high performing Fe-N-C catalysts derived from Fe/melamine-decorated polyaniline. The optimal catalyst displays much better ORR onset and half-wave potentials (1.00 and 0.86 V) than that of the melamine-free catalyst (0.97 and 0.83 V) and even the commercial Pt/C (0.99 and 0.83 V), respectively. It also shows a decent stability during 20 000 cycles of accelerated durability test (ADT) with only 15 mV loss in the half-wave potential. Physical and electrochemical characterizations demonstrate that introduction of melamine could increase the percentage of surface pyrrolic N species and non-crystalline Fe species, which would be responsible for the significant improvement in the catalytic performance toward ORR.