fig2

Figure 2. (A) Schematic illustration of the synthesis procedure of the Co-N/C-U catalyst. SEM images of (B) Co-N/C, and (C) Co-N/C-U. (D) TEM and (E) HRTEM images of Co-N/C-U. (F) AC HAADF-STEM image and (G) EDS elemental mappings of Co-N/C-U.