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

Developing efficient non-precious metal electrocatalyst 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-Nx 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 (Pmax = 151 mW cm-2) than the commercial 20 wt% Pt/C (OCP = 1.441 V; Pmax = 119 mW cm-2) under similar experimental conditions. Defects in the catalyst could modulate the electronic structure of the Fe-Nx-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 implication in energy conversion devices.