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 overlooked part of the electrocatalyst, plays a crucial role for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of the zinc–air battery (ZAB). Herein, a Fe, Co, N, and S co-doped three-dimensional (3D) porous graphene-like catalyst (FeCo–N,S-G) is prepared via the dual template strategy. CaCl 2 is used as an inexpensive and readily available raw material to create pores. ZnCl 2 evaporates and etches carbon substrates at high temperatures to further prepare multi-level pores and abundant defect structures. The porous structure is important for exposing high-density active sites and facilitates mass transfer. The prepared catalyst exhibits excellent ORR and OER activity. For ORR, the half-wave potential of FeCo–N,S-G is 0.88 V vs RHE. For OER, the overpotential of the catalyst is 350 mV at a current density of 10 mA cm –2 in 1 M KOH. Furthermore, FeCo–N,S-G exhibits enhanced hydrogen evolution reaction (HER) performance. The FeCo–N,S-G catalyst is applied to the air cathode of homemade aqueous ZAB and all-solid-state flexible ZAB, and the ZAB exhibits high peak power density and good charge/discharge stability performance.