Pt-Like Oxygen Reduction Activity Induced by Cost-Effective MnFeO2 /N-Carbon.

The development of effective and affordable electrocatalysts for the oxygen reduction reaction (ORR) is critical for the renewable-energy technologies. Here, we present a new manganese iron oxide (MnFeO2 ) as a cost-effective material for the ORR with Pt-like electrochemical properties. Pyrolysis of hybrid agar hydrogel on NaCl nanocrystals furnishes a unique structure in which the active MnFeO2 particles are uniformly immobilized in the nitrogen-doped porous carbon aerogels (MnFeO2 /NPC). Nitrogen-doped carbon is introduced to construct porous mass-transfer channels and reduce self-aggregation of the MnFeO2 particles. It is found that the formation of the MnFeO2 phase greatly depends on the pyrolysis temperature. Benefiting from the synergy of MnFeO2 and NPC, the MnFeO2 /NPC can actually be as good as the Pt/C catalyst for the ORR, with an onset-potential of 0.98 V and a half-wave potential of 0.86 V, combined with demonstrating a superior stability and tolerance to methanol.