MOF-derived Porous Carbon Nanofiber Assembly as High Efficiency ORR Electrocatalysts for Zinc-air Batteries.

Reasonable construction of high activity and low cost non-noble metal oxygen reduction reaction (ORR) catalyst is of great importance for the wide application of zinc-air batteries (ZABs). Using bimetallic MOF as a precursor combined with electrospinning, high-temperature carbonization and electrodeposition, we successfully developed a porous carbon nanofiber (Co@Fe-CNFs-1000) with bimetallic active center as an efficient catalyst for ORR. The successful construction of this special core-shell structure directly explores the synergy between different active centers. The results showed that the synthesized Co@Fe-CNFs-1000 catalyst exhibited ORR performance comparable to that of Pt/C in 0.1 mol/L KOH electrolyte, high half-wave potential (E_1/2=0.81 V) and limiting current density (J_L=5.4 mA-cm⁻²). In addition, homemade liquid ZABs with Co@Fe-CNFs-1000 as the air cathode showed excellent power density (155.8 mW·cm⁻²), specific capacity (780.6 mAh·g_Zn⁻¹) and long-term stability (over 100 h at 2 mA·cm⁻²), surpassing even Pt/C-based batteries. In addition, the flexible solid-state ZABs assembled based on Co@Fe-CNFs-1000 demonstrates excellent flexibility and durability. This work provides a new idea for constructing ORR catalysts with high activity centers. [ABSTRACT FROM AUTHOR]