fig7
Figure 7. (A) Schematic illustration of the formation of Ni-NC@Ni. (B) HAADF-STEM and (C) AC HAADF-STEM images of Ni-NC@Ni. (D) High-resolution Ni 2p and (E) N 1s XPS spectra of Ni-NC@Ni (inset: atomic structure)[122]. AC HAADF-STEM: Aberration-corrected high angle annular dark field scanning transmission electron microscopy.