fig2
Figure 2. (A and C) The SEM pictures; (B and D) TEM pictures; (E and F) corresponding EDS mappings; and (G and H) HAADF-STEM images of Co-N4-C and Co-N4Cl-C, respectively. SEM: Scanning electron microscope; TEM: transmission electron microscopy; EDS: energy dispersive spectroscopy; HAADF-STEM: high-angle annular dark-field scanning TEM.
