Multi-level Porous Fe, Co, N, S Co-doped Three-Dimensional Graphene-like Catalyst as the Excellent Trifunctional Electrocatalyst for Liquid and Flexible All-Solid-State Zinc-Air Batteries

The porous structure engineering, as an easily overlookedpartof the electrocatalyst, plays a crucial role for the oxygen reductionreaction (ORR) and oxygen evolution reaction (OER) of the zinc-airbattery (ZAB). Herein, a Fe, Co, N, and S co-doped three-dimensional(3D) porous graphene-like catalyst (FeCo-N,S-G) is preparedvia the dual template strategy. CaCl2 is used as an inexpensiveand readily available raw material to create pores. ZnCl2 evaporates and etches carbon substrates at high temperatures tofurther prepare multi-level pores and abundant defect structures.The porous structure is important for exposing high-density activesites and facilitates mass transfer. The prepared catalyst exhibitsexcellent ORR and OER activity. For ORR, the half-wave potential ofFeCo-N,S-G is 0.88 V vs RHE. For OER, the overpotential ofthe catalyst is 350 mV at a current density of 10 mA cm(-2) in 1 M KOH. Furthermore, FeCo-N,S-G exhibits enhanced hydrogenevolution reaction (HER) performance. The FeCo-N,S-G catalystis applied to the air cathode of homemade aqueous ZAB and all-solid-stateflexible ZAB, and the ZAB exhibits high peak power density and goodcharge/discharge stability performance.