fig5

Figure 5. (A) High angle annular dark-field STEM image of Fe-NC SACs. (B) Fitting lines of Fe-NC SACs in R-space with an inset schematic of the Fe-N₄ structure. (C) Schematic of ORR and OER reaction mechanisms on Fe-NC SACs. Reproduced with permission: Copyright 2020, Royal Society of Chemistry^[115]. (D) Co-N₄/C and Co cluster|Co-N₄/C models. (E) Free-energy diagram of two models at U = 0 and 1.23 V. Reproduced with permission: Copyright 2019,Wiley^[118]. (F) Polarization curves and corresponding power densities of Co-NPs@NC, Co-ACs@NC, Co-SAs@NC and Pt/C-based Zn-air batteries. Reproduced with permission: Copyright 2019, Wiley^[119]. (G) HAADF-STEM image of Cu-NrC-60. (H) STM simulation images of Cu-NrC-60. (I) Volcano plot of the relationship between ORR activity and D_EO of Cu-N₂, Cu-N₃, Cu-N₄, a CuPc molecule and N-doped graphene. Reproduced with permission: Copyright 2016, Royal Society of Chemistry^[120].