N‐Doped 3D Carbon Aerogel with Trace Fe as an Efficient Catalyst for the Oxygen Reduction Reaction

Abstract The development of highly efficient, stable, and low‐cost oxygen reduction reaction (ORR) electrocatalysts is urgently required. Herein, a three‐dimensional (3D) N‐doped carbon aerogel with trace Fe (ca. 0.60 wt%) was synthesized by using carbon aerogel as the main raw material with facile KOH activation and a solid‐state pyrolysis technique. The pyrolysis temperature and trace amount of Fe play crucial roles in the ORR activity. The optimal product (Fe−N‐CA‐800) displayed onset and half‐potentials of 0.918 and 0.798 V in alkaline solution and 0.801 and 0.592 V in acidic media, respectively. Besides, the methanol crossover effect and long‐term stability for Fe−N‐CA‐800 were better than those of Pt/C. Furthermore, the Fe‐N x sites were proven to be the main ORR catalytic sites by using SCN − . The robust 3D structure with hierarchical pores, unique chemical composition, and uniform Fe‐N x active sites contributed to the superior ORR performance. The low‐cost and efficient Fe−N‐CA‐800 catalyst presents potential in fuel cells and metal‐air batteries.