An Fe-N-C electrocatalyst with dense active sites synthesized by expeditious pyrolysis of a natural Fe-N4 macrocyclic complex

Platinum group metal (PGM)-free ORR catalysts containing highly dispersed metal-nitrogen sites have been demonstrated as the most promising alternatives to Pt-based catalysts. However, it remains a tremendous challenge to synthesize efficient ORR catalysts with dense active sites expeditiously. Herein, a series of highly dispersive Fe-N-C catalysts derived from N-doped Ketjen Black (N-KJB) and hemin were synthesized by a simple rapid pyrolysis method within 1 min. Benefitting from the spatial confinement effect of N-KJB and high-coordination natural iron source, the highly dispersive Fe is higher than 3 wt% without Fe particle agglomeration. The optimized Fe-KJB-3-60A electrocatalyst exhibits a superior ORR activity with a half-wave potential of 0.90 V in 0.1 M KOH and 0.79 V in 0.1 M HClO4. When used as the cathode catalyst in Zn-air batteries and proton exchange membrane fuel cells, Fe-KJB-3-60A exhibits a maximum peak power density of 251 mW cm(-2) and 348 mW cm(-2), respectively.

Automated summary

A highly dispersed Fe-N-C catalyst with dense active sites was successfully synthesized using a simple and rapid pyrolysis method. The catalyst exhibited superior ORR activity in alkaline and acidic environments. When applied in zinc-air batteries and proton exchange membrane fuel cells, the catalyst showed high peak power density.