Fig. 4. (A) Cyclic voltammograms for Co–N/CNs with different cobalt precursors in O2-saturated 0.10 M KOH at scan rate of 50 mV s−1. (B) Histograms for OER and ORR electrocatalytic properties of Co–N/CNs with different cobalt precursors (sulfate, acetate, chloride and nitrate). (C) Histograms for the relationship between water solubility and nanoparticle size. (D) Schematic diagram of the self-assembly process.
