In situ formation of self-antistacking FeCoOx 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 (FeCoOx) are directly grown on 2D N-doped graphene (NG). The in situ grown FeCoOx particles can alleviate the NG interlaminar restacking, ensuring abundant channels for diffusion of O-2/OH- species, while the NG allows rapid electron flow. Benefiting from this self-antistacking 3D-on-2D structure and synergetic electrocatalysis, FeCoOx@NG demonstrated excellent activity for both ORR and OER (Delta E = 0.78 V), which is superior to that of the binary mixtures of Pt/C and RuO2 (Delta E = 0.83 V). A homemade ZAB with 20%-FeCoOx@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.