Boosting ORR/OER bifunctional electrocatalysis by promoting electronic redistribution of Fe-N-C on CoFe-FeNC for ultra-long rechargeable Zn-air batteries.

Fe-N-C materials are among the most promising platinum group metals-free catalysts for air cathode of Zn-air batteries (ZABs). However, they are still limited by sluggish reaction kinetics. Herein, we synthesize a novel and effective mesoporous carbon embedded with CoFe nanoclusters, coated with graphitic carbon layers (denoted as CoFe-FeNC). CoFe-FeNC is derived from the pyrolysis of metal-organic complex precursors with grafted iron porphyrin. The CoFe-FeNC catalyst exhibits a half-wave potential (E 1/2) of 0.876 V for the oxygen reduction reaction (ORR) and a potential of 1.526 V at 10 mA cm−2 (E j=10) for the oxygen evolution reaction (OER) in alkaline solutions. Theoretical calculations reveal that the presence of CoFe clusters regulates the electronic structure, optimizing adsorption and desorption during the catalytic reaction. Moreover, flow-ZABs utilizing CoFe-FeNC as the cathode material demonstrate a high specific capacity of 767.5 mAh g Zn −1 and an ultra-long lifespan exceeding 1200 h. Additionally, flexible quasi-solid-state rechargeable ZABs incorporating CoFe-FeNC electrocatalysts as the cathode demonstrate well cycling and mechanical flexibility. [Display omitted] • A facile method for the fabrication of mesoporous nitrogen-carbon material decorated by CoFe clusters (CoFe-FeNC). • CoFe-FeNC showed highly efficient catalytic activities for OER and ORR in alkaline media. • The bifunctional catalysts was employed in flow and flexible Zn-air battery. • Theoretical calculations claim the electronic structure and d-band center modulation between Fe-N-C and CoFe clusters. [ABSTRACT FROM AUTHOR]