NiFe-LDH nanosheets anchored on Fe, N decorated carbon nanofibers as efficient bifunctional electrocatalysts for long-term rechargeable Zn-air batteries

The practical application of rechargeable Zn-air batteries relies on the advance of low-cost and high-performance oxygen evolution/reduction reaction (OER/ORR) bifunctional electrocatalyst. Herein, a noble-metal-free bifunctional electrocatalyst is rationally designed by anchoring the nickel‑iron layered double hydroxide (NiFe-LDH) nanosheets on the Fe, N decorated carbon nanofibers (LDH/FeNCF). The resultant LDH/FeNCF exhibits remarkable bifunctional catalytic activities for OER/ORR, delivering a reversible oxygen electrode index (ΔE) of 0.70 V, significantly surpassing that of noble-metal-based Pt/C-RuO2 benchmark (ΔE = 0.77 V) and those of most bifunctional electrocatalysts ever reported. Moreover, the primary Zn-air batteries based on LDH/FeNCF cathode behave robust stability once discharging at 5 and 10 mA cm−2 for 150 h, and the as-assembled rechargeable Zn-air batteries can be durably cycled for 690 h, suggesting their promising applications in the field of rechargeable Zn-air batteries, especially in terms of the facile process and low cost.