fig4

Figure 4. (A) OER LSV curves; (B) TOF values of Fe-Co-Ni trimetallic materials with different ratios of Fe/Co/Ni; (C) OER LSV curves of the Fe₃₀Co₃₀Ni₃₀-PNC and RuO₂ electrocatalysts before and after 25,000 s; (D) ORR polarization plots for Fe-Co-Ni trimetallic materials; (E) ORR LSV curves of the Fe₃₀Co₃₀Ni₃₀-PNC and Pt/C electrocatalysts before and after 16,000 CV cycles; (F) The combined ORR and OER polarization plots of different catalysts and the corresponding potential gap (ΔE = E_j=10 - E_1/2); (G) ΔE comparison of the Fe₃₀Co₃₀Ni₃₀-PNC with the recently reported high-performance bifunctional catalysts. OER: Oxygen evolution reaction; LSV: linear sweep voltammetry; TOF: turnover frequency; PNC: phosphorus and nitrogen doped carbon; ORR: oxygen reduction reaction; CV: cyclic voltammetry.