Biomimetic construction of bifunctional perovskite oxygen catalyst for zinc-air batteries

As a promising strategy for the catalyst design and optimization, the biomimetic method can greatly improve the activity of oxygen redox catalysts. In this work, we construct a Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF)-ceria (CeO2) hybriding oxygen redox catalyst (BSCCF-NF-H) by imitating the structure and function of fish gills. In our BSCCF-NF-H catalyst, the perovskite nanofibers with the diameter of 200 nm prepared by electrospinning can imitate gill filaments to transfer oxygen species, while the CeO2 nanoparticles uniformly growing on the surface of perovskite nanofibers by exsolution method can imitate lamellas to adsorb oxygen. Thanks to the biomimetic structure and function, BSCCF-NF-H shows the greatly enhanced catalytic activity toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) comparing with the pristine BSCF. BSCCF-NF-H shows the low potential at 10 mA cm-2 (Ej=10) of 1.62 V toward OER and half-wave potential (E1/2) of 0.66 V toward ORR. Also, the bifunctional stabilities of BSCCF-NF-H are much higher than that of BSCF after the long-term durability tests. Benefiting from these advantages, BSCCF-NF-H is successfully applied as the bifunctional oxygen redox catalyst for aqueous and solid-state flexible zinc-air batteries (ZABs). Our work can provide an inspiring way for further explorations of high-performance perovskite oxygen redox catalyst.