Creating Defects in the Active Site of Fe−N−C Catalyst Promotes Catalytic Performance for Oxygen Reduction Reaction

Abstract Developing efficient non‐precious metal electrocatalysts to replace Pt‐based noble metal catalysts for oxygen reduction reaction (ORR) in energy conversion devices is highly desirable. Atomically dispersed Fe−N−C catalysts are the most promising alternatives of Pt for ORR; however, enhancing their intrinsic activity via active site modulation is still a challenge. Using an iron porphyrin‐functionalized MOFs as the precursor, we prepared a defects‐rich Fe−N−C catalyst and modulated its intrinsic activity by creating defects near the Fe−N_x sites through decarboxylation reaction. Due to the synergistic effect of the improved porous structure and created defects, the prepared Defects‐FeNC exhibited excellent performance for ORR with half‐wave potential of 0.895 V vs. RHE in alkaline media. The Defects‐FeNC loaded Zn‐Air battery delivered much higher open circuit potential (OCP=1.463 V) and maximum power density (P_max=151 mW cm⁻²) than the commercial 20 wt.% Pt/C (OCP=1.441 V; P_max=119 mW cm⁻²) under similar experimental conditions. Defects in the catalyst could modulate the electronic structure of the Fe−N_x−C center that further promoted the catalyst catalytic activity for ORR. This work provides a facile active‐sites‐engineering approach for boosting the Fe−N−C catalyst ORR performance, which shows promising implications in energy conversion devices.