fig11

Figure 11. (A) Schematic and reaction mechanism of Cu-SAs/N-C; (B) K³-weighted χ(k) functions of EXAFS spectra; (C) copper K-edge XANES spectra of Cu-SAs/N-C; (D) EXAFS fitting curve of Cu-SAs/N-C. Inset shows the proposed Cu-N₄ coordination environment. LSV curves of (E) Pt/C, Cu-SAs/N-C and pyrolyzed ZIF-8 and (F) Cu-SAs/N-C before and after 5,000 cycles of accelerated durability testing; (G) Comparison between the HPRR and ORR. Reactions were performed in N₂-saturated electrolyte (3.5 mM H₂O₂) (A-G reproduced with permission from Springer Nature, copyright 2018)^[155]; (H) Schematic showing the preparation process of ZnO₃C and ZnN₄ electrocatalysts; (I) optimized geometric model of Zn single atoms in ZnN₄ and ZnO₃C; (J) Free energy diagrams of the 2e^- and 4e^- ORR pathways on ZnO₃C and ZnN₄ at 0 V vs. RHE (H-J reproduced with permission from Wiley-VCH, copyright 2021)^[156]; (K) Aqueous synthesis scheme of Mn-N-C catalysts and (L) fuel-cell performances of different catalysts under H₂-O₂ (K and L reproduced with permission from the American Chemical Society, copyright 2020)^[130]. EXAFS: Extended X-ray absorption fine structure; SAs: single atoms; ZIF: zeolite imidazole frameworks; ORR: oxygen reduction reaction; XANES: X-ray absorption near-edge structure; HPRR: hydrogen peroxide reduction reaction.