N-doped mesoporous FeNx/carbon as ORR and OER bifunctional electrocatalyst for rechargeable zinc-air batteries

The development of low-cost bifunctional catalysts with high catalytic activity and durability for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a critical step for successful commercialization of Zn-air batteries. In this study, N-doped mesoporous carbon containing dispersed FeNx species is prepared and tested as an ORR and OER bifunctional catalyst for this battery type. Physical-chemical characterization of the newly prepared material demonstrated that NaCl can be effective as a porous structure forming template during carbonization. Resulting mesoporous structure containing FeNx species provides significant number of ORR and OER active sites. The optimized catalyst displays higher limiting current density and more positive half-wave potential for ORR than commercial Pt/C, as well as lower overpotential for OER than RuO2 in KOH electrolyte. Furthermore, the obtained carbon material used as an air cathode in a specially assembled rechargeable Zn-air cell demonstrates electrocatalytic performance superior to those of Pt/C and RuO2 electrodes, which makes it a promising non-precious metal bifunctional catalyst for Zn-air batteries.