Structure Preferred Spinel Ferrite on Polypyrrole Derived N‐Doped Carbon Nanofibers as Bifunctional Electrocatalyst for Zn‐Air Battery

Abstract The explorationof noble metal free bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is very important for Zn‐air batteries (ZABs). Spinel ferrites are famous bifunctional ORR/OER electrocatalysts. Herein, to further improve their ORR and OER activities, we anchor CoFe₂O₄ on N‐doped carbon nanofibers (NCNF) derived from polypyrrole (PPy) and obtain CoFe₂O₄ loaded NCNF (CoFe₂O₄@NCNF). In its structure, CoFe₂O₄ particles with small size distribute evenly on NCNF. The combination of CoFe₂O₄ and NCNF generates excellent ORR activity with typical four‐electron character in both alkaline and neutral electrolyte. In OER, the activity of CoFe₂O₄@NCNF is also excellent. A rechargeable ZAB is constructed with CoFe₂O₄@NCNF as cathode material. The specific capacity and energy density of this ZAB reach 807.4 mAh g⁻¹ and 963.6 Wh kg⁻¹ at 10 mA cm⁻², respectively. ZAB can keep stable after continuous charge/discharge test for 120 h. This work not only provides an efficient and low cost cathode material for ZABs, but also clarifies the structure‐activity relationship in ORR/OER for spinel ferrites.