Enhancing activity and stability of FeNC catalysts through co incorporation for oxygen reduction reaction

Abstract

FeNC single atom catalysts (SACs) have attracted great interest due to their highly active FeN₄ sites. However, the pyrolysis treatment often leads to inevitable metal migration and aggregation, which reduces the catalytic activity. Moreover, due to the Fenton reaction caused by FeNC in alkaline and acidic solutions, the presence of Fe and peroxide in electrodes may generate free radicals, resulting in serious degradation of the organic ionomer and the membrane. Herein, we report an original strategy of introducing Co single atoms into FeNC catalysts, forming atomically dispersed bimetallic active sites (FeCoNC) and improving the activity and stability of the catalyst. Benefiting from this strategy, FeCoNC catalyst exhibits excellent oxygen reduction reaction (ORR) activity in alkaline media (E_1/2 = 0.88 V) and in acidic media (E_1/2 = 0.77 V). As the cathode of Zn-air battery (ZAB), FeCoNC shows an excellent peak power density of 142.8 mW cm^-2 and a specific capacity of 806.6 mAh/g_Zn. This work provides a novel avenue to optimize and enhance the ORR performance of atomic dispersed FeNC catalysts.

Keywords: Bimetallic active sites; Fe–N–C catalysts; Oxygen reduction reaction; Zn-air batteries.