fig8

Figure 8. (A) The ORR and OER free energy diagram of CoCoNiN₉-G, NiNiCoN₉-G, CoCoCoN₉-G, FeCoN₆-G and FeFeN₆-G under U = 1.23 V; (B and C) The volcano plots of OER and ORR^[46], Copyright 2022 Elsevier B.V.; (D) LSV curves for ORR in O₂-saturated 0.1 m KOH at 1,600 rpm; (E) Tafel plots; (F) The TOF values Co₂MnN₈/C, Pt/C, Co-N/C and Mn-N/C at 0.8 V vs. RHE; (G) LSV curves of Co₂MnN₈/C and Pt/C at 20,000 cycles^[40], Copyright 2023 Wile-VCH GmbH; (H) Summary of onset potential, half-wave potential and limiting current density for all samples; (I) Tafel plots; (J) LSV curves of FeACs/NPS-HC-900 at 10,000 CV cycles^[39], Copyright 2023 Wile-VCH GmbH. ORR: Oxygen reduction reaction; OER: oxygen extraction reaction; LSV: linear sweep voltammetry; TOF: turnover frequency; RHE: reversible hydrogen electrode.