Maximizing the Active Site Densities of Single-Atomic Fe–N–C Electrocatalysts for High-Performance Anion Membrane Fuel Cells

Iron- and nitrogen-doped carbon (Fe–N–C) catalysts have received significant attention owing to their high oxygen reduction reaction (ORR) activities, which are comparable to those of state-of-the-art Pt/C catalysts. This high ORR activity originates from the atomically dispersed Fe coordinated with the nitrogen atom (Fe–N x ) active site. Increasing the Fe–N x active site density can enhance the ORR activity. In this study, we suggest a facile and effective method for maximizing the active site densities using a simple ZnCl 2 activation method. ZnCl 2 activation was applied to the metal organic framework-derived Fe–N–C catalyst that exhibits superior ORR activity compared to Pt/C and a recently reported nonprecious metal catalyst. Through various electrochemical analyses, we confirmed that this activity originates from the effectively increased active site density. The anion-exchange me…