Rapid microwave-assisted preparation of high-performance bifunctional Ni3Fe/Co-N-C for rechargeable Zn-air battery

Precious metal-free bifunctional catalysts offer scalable possibilities for achieving oxygen cathodes in rechargeable metal-air batteries. Literature thus far suggests that the oxygen reduction and evolution reactions (i.e ORR and OER) take place at different active sites. However, the design and preparation of oxygen electrocatalysts with high-performance is still a great challenge. This work develops a general approach to introduce a nanoparticle that offers oxygen evolution reaction sites onto an oxygen reduction reaction catalyst via rapid microwave treatment. The metal-organic frameworks (Co, ZIF-8) derived Co-N-C with high ORR performance is employed as a support to homogeneously disperse OER active Ni3Fe nanoparticles. Potentials of 1.54 V and 0.79 V have been achieved at current densities of 10 mA cm(-2) for OER and 3 mA cm(-2) toward ORR, respectively. The developed rechargeable Zn-air battery assembled with Ni3Fe/Co-N-C as an oxygen-electrode exhibits superior efficiency and robust durability, exceeding that of commercial Pt/C + IrO2. Furthermore, the satisfactory activity of our fabricated wristband shows the successfully practical application of flexible Zn-air batteries for wearable devices.