NiFe layered double hydroxide (LDH) anchored, Fe single atom and nanoparticle embedded on nitrogen-doped carbon-CNT (carbon nanotube) framework as a bifunctional catalyst for rechargeable zinc-air batteries

Abstract

Zinc-air batteries (ZAB) have significant potential for practical energy storage, but their rechargeability has been limited by the lack of a suitable bifunctional catalyst. Here, we developed NiFe LDH-A-Fe/NC-CNT, a remarkable bifunctional catalyst that is built on a hierarchically porous nitrogen-doped carbon and carbon nanotube (NC-CNT) framework enriched with iron single atoms and nanoparticles, with nickel‑iron layered double hydroxides (NiFe LDH) anchored onto it. The NiFe LDH-A-Fe/NC-CNT exhibited remarkable performance in the ORR, with Eonset of 0.94 V, a half-wave potential of 0.84 V, and a limited current of 6.89 mA cm−2. A remarkable Eonset of 1.47 V and a potential of 1.59 V at 10 mA cm−2 (Ej = 10) in the OER were also observed. Significantly, the difference in potential (ΔE) between the ORR and OER was only 0.74 V. The stability tests, tolerance assessments, and poisoning experiments consistently demonstrated the superior performance of this cutting-edge catalyst in comparison to the commercial Pt/C and RuO2. In ZAB tests, it achieves a discharge capacity of 818 mAhg−1 and an impressive power density of 293 mWcm−2, enduring nearly 1000 cycles (320h). Flexible ZABs with this catalyst maintain a 629 mAhg−1 capacity, a power density of 195 mWcm−2, and a lifespan of 95 h (280 cycles), outperforming benchmark catalysts. In conclusion, a remarkable bifunctional catalyst was synthesized, demonstrating its immense capacity for utilization in zinc-air batteries.