1. (a) Magnified HAADF-STEM image of Cu-SA/SNC; (b) Ex situFT k³-weighted Cu K-edge EXAFS spectra of Cu-SA/SNC; (c) Schematic interfacial model of Cu-SA/SNC; (d) ORR polarization curves of different catalysts; (e) Kinetic currents at 0.85 V (vs. RHE) and half-wave potentials of Cu-SA/SNC and their references; (f) Performances of Cu-SA/SNC and Pt/C-based Zn-air batteries^[31]

2. Schematic, characterization and electrochemical test of atomically dispersed Cu-N_x site catalyst synthesis^[34]

3. (a) Scheme of the formation of Cu ISAS/N-C catalyst; Aberration-corrected high-angle annular dark-field scanning transmission electron microscope (AC HAADF-STEM) images of (b) NC and (c) Cu ISAS/NC; (d) ORR polarization curves and (e) performances of Cu ISAS/NC and Pt/C-based Zn-air batteries^[37]

4. (a) Schematic illustration of the synthesis procedure, (b) HAADF-STEM image and (c) ORR polarization curves of Mg-N-C^[48]

5. Atomic dispersion of Ru-SSC, electrocatalytic tests towards ORR and probe experiment^[52]

6. (a) HAADF-STEM image of Pt₁-N/BP, (b) Pt L3-edge XANES, k²-weighted R-space FT spectra from (c) EXAFS, (d) ORR polarization curves for all samples^[60]

7. (a) Schematic diagram of Fe-N/P-C preparation and (b, c) corresponding electrochemical performances^[65]

8. Structural characterizations of Fe-SAs/NSC, Co-SAs/NSC and Ni-SAs/NSC^[70]

9. (a) Formation process of Cu-SA/NC(meso) catalysts; (b) SEM image, (c) TEM image, and (d) corresponding SAED pattern of Cu ⁺-SA/NC(meso)-7; (e) Cu2p high-resolution XPS surveys of Cu-SA/NC (meso) catalysts; (f) Linear sweep voltammetry (LSV) curves of Cu⁺-SA/NC (meso)-7 and comparison samples; (g) Comparison of ORR activities for Cu-SA/NC (meso) catalysts^[74]

10. Formation process and structural characterizations of Mn-N₂C₂^[75]