Fig. 1. (A) TEM and (B and C) HR-TEM images of the catalyst Fe–Fe₃C@NC-800; the inset shows the size distribution of metallic Fe nanoparticles. (D) HAADF-STEM and the corresponding EDX elemental mappings of individual Fe–Fe₃C@NC-800, (E) schematic illustration of the catalyst Fe–Fe₃C@NC-800, and (F) XRD pattern of the catalyst Fe–Fe₃C@NC-800.