Iron Atom-Cluster Strategy Synthesis of Hierarchically Porous Fe–N–C Catalysts for Proton Exchange Membrane Fuel Cells

Developing nonprecious metal-nitrogen-doped carbon (M–N–C) catalysts with high activity and stability is critical to their widespread use in fuel cells; however, these catalysts still face considerable challenges. Herein, a novel iron atom-cluster strategy for the synthesis of iron-based N–C catalyst comprising Fe nanoparticles (Fe NPs) surrounded by Fe-N x sites is developed for oxygen reduction reactions in an acidic fuel cell. Iron oxide NPs were incorporated into zeolitic imidazolate framework-8 (ZIF-8)-derived carbon materials and pyrolyzed at high temperatures using NaCl as a modifier to produce Fe NPs and Fe-N x composite active sites. The half-wave potential of the optimized Fe NP /FeNC-NaCl material was substantially improved to 0.81 V. Furthermore, even after 15,000 cycles, the half-wave potential of the catalyst remained essentially unchanged. As a cathode catalyst for fuel cells, it realized a high peak power density of 436 mW/cm 2 under a practical H 2 -air atmosphere. Therefore, this study presents a new approach for designing and synthesizing electrocatalytic materials with high catalytic activity and stability.