Figure 10.

a) Synthesis strategy for preparation of Fe–N–C catalysts. b,c) ORR polarization curves of various catalysts in O₂‐saturated b) 0.1 m KOH and c) 0.1 m HClO₄. a–c) Reproduced with permission.86 Copyright 2019, Wiley‐VCH. d) ORR polarization curves and e) kinetic currents (J _K) (at 0.85 V) and half‐wave potentials for Cu–N–C, N–C and Pt/C catalysts in O₂‐saturated 0.1 m KOH solution. f) Electron transfer number (n) and H₂O₂ yield for Cu–N–C and Pt/C. g) i–t curves of Cu–N–C and Pt/C for 10 000 s at a constant potential. Calculated free‐energy diagram for ORR on h) Cu–N₂ and i) Cu–N₄ active sites. The inset structures represent the optimized structures of Cu–N₂ and Cu–N₄. The yellow, blue, and light pink balls represent carbon, nitrogen, and copper atoms, respectively. d–i) Reproduced with permission.65 Copyright 2018, The Royal Society of Chemistry.