Facile synthesis of flower-like dual-metal (Co/Zn) MOF-derived 3D porous Co@Co-NPC as reversible oxygen electrocatalyst for rechargeable zinc-air batteries

Nowadays, Zn-air batteries have been widely applied in miniature electronic devices and power stations. However, it is imperative but challenging to synthesize efficient non-precious metal electrocatalysts for popularizing application of Zn-air batteries. Herein, the three-dimensional porous Co@Co-NPC is prepared by doping P into flower-like Co/Zn-MOF-derived Co-N-C during the carbonization process. The obtained 3D-Co@Co-NPC possesses an excellent catalytic activity, showing a half-wave potential of 0.872 V for ORR and potential of 1.692 V at 10 mA cm−2 for OER. When employed as air-cathode catalyst in Zn-air battery, 3D-Co@Co-NPC shows a high power density of 182.5 mW cm−2 and a high capacity of 764 mAh g−1. Besides, it displays an excellent charging-discharging cycle stability (over 90 h). The outstanding ORR/OER performance of 3D-Co@Co-NPC are mainly attributed to the doping of P element, which can tune the electronic structure of Co-N-C matrix. The pickling experiment proves that Co nanoparticle can make contribution to ORR/OER activity.