In situ formation of self-antistacking FeCoO_x on N-doped graphene: A 3D-on-2D nanoarchitecture for long-life Zn–air batteries

Before the practical application of rechargeable Zn–air batteries (ZABs), a critical issue regarding the inherent slow reaction kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) must be addressed. Here, we fabricate a cost-effective bifunctional oxygen electrocatalyst with a self-antistacking structure, where three-dimensional (3D) Fe–Co bimetallic oxide particles (FeCoO_x) are directly grown on 2D N-doped graphene (NG). The in situ grown FeCoO_x particles can alleviate the NG interlaminar restacking, ensuring abundant channels for diffusion of O₂/OH⁻ species, while the NG allows rapid electron flow. Benefiting from this self-antistacking 3D-on-2D structure and synergetic electrocatalysis, FeCoO_x@NG demonstrated excellent activity for both ORR and OER (ΔE = 0.78 V), which is superior to that of the binary mixtures of Pt/C and RuO₂ (ΔE = 0.83 V). A homemade ZAB with 20%-FeCoO_x@NG delivers a specific capacity of 758.9 mAh g⁻¹, a peak power density of 215 mW cm⁻², and long-term cyclability for over 400 h. These research results suggest that designing a bimetallic oxide/N-doped carbon 3D-on-2D nanoarchitecture using an in situ growth strategy is an attractive and feasible solution to overcome electrocatalytic problems in ZABs.