FIGURE 4 Microstructure and morphology characterizations of Ni@N-C SACs prepared by using lignin and chitosan as chelating agents: (a) TEM images. (b) Corresponding EDX elemental mapping. and (c) Aberration-corrected HAADF-STEM images of Ni@N-C SAC prepared with lignin. (d) TEM images. (e) Corresponding EDX elemental mapping and (f) Aberration-corrected HAADF-STEM images of Ni@N-C SAC prepared with chitosan.