fig4

Figure 4. (A) ORR polarization curves and (B) Tafel plots of the synthesized catalysts and commercial PtCoC in O₂-saturated 0.1 M HClO₄ at 25 °C. (C) The MA and SA of the synthesized catalysts at 0.85 V vs. RHE in O₂-saturated 0.1 M HClO₄ at 25 °C. (D) ORR polarization curves comparison, (E) E_1/2 and MA comparison in 0.1 M HClO₄ and 0.1 M HClO₄ + 0.1 M H₃PO₄ at 25 °C. (F) Radar chart of ORR performance for the synthesized catalysts in 0.1 M HClO₄ + 0.1 M H₃PO₄ at 25 °C. (G) Correlation among phosphate anion coverage, O-reduction area, and the increment in E_1/2 for the synthesized catalysts as the testing temperature increases from 25 °C to 80 °C in 0.1 M HClO₄ + 0.1 M H₃PO₄. (H) Tafel Slopes in 0.1 M HClO₄ + 0.1 M H₃PO₄ at 80 °C. (I) ORR polarization curves comparison in 0.1 M HClO₄ at 25 °C and 0.1 M HClO₄ + 0.1 M H₃PO₄ at 80 °C. (J) Correlation of the E_1/2 decay values and CO-stripping area retention in 0.1 M HClO₄ at 25 °C and in 0.1 M HClO₄ + 0.1 M H₃PO₄ at 80 °C, Retention% = (value in 0.1 M HClO₄ + 0.1 M H₃PO₄/value in 0.1 M HClO₄) × 100%. (K) Comparison of E_1/2 and (L) MA of the synthesized catalysts after 10,000 potential cycles in 0.1 M HClO₄ + 0.1 M H₃PO₄ at 80 °C.