Fig. 2.

(A) RRDE measurements recorded with FePc NTs-rGO, FePc Agg-rGO, FePc-rGO, rGO, and 20% Pt/C in O₂ saturated 0.1 M KOH, 1600 rpm, 10 mV s⁻¹. During the measurements, the potential of ring electrode was kept constant at 1.07 V. (B) The HO₂⁻ percentage of ORR on various catalysts, derived from the corresponding RRDE measurements. (C) TOFs of Fe sites derived from the Koutecky–Levich analysis. (D) A polarization curve and corresponding power density plot of the zinc-air battery using FePc NTs-rGO as the cathode catalyst compared with the battery using Pt/C catalyst.