Fe/Co-Loaded Hollow Carbon Sphere Nanocomposites as Excellent Cathodic Catalysts of Zn-Air Battery

The development of an efficient, stable and low-cost cathode catalyst is necessary for the practical application of Zn-air batteries. In this paper, Fe3+/Co2+ ions were in situ incorporated into polydopamine during the polymerization of dopamine on the surface of the SiO2 spheres. After subsequent pyrolysis and leaching SiO2, the products loaded with different metals (NHCS-Fe, NHCS-Co, NHCS-Fe1Co0.6, NHCS-Fe1Co4, NHCS-Fe1Co10) were obtained. The samples possess a typical hollow carbon sphere (HCS) structure and show efficient oxygen reduction reaction (ORR) performance under neutral and alkaline conditions. Especially in the neutral electrolyte, the NHCS-Fe exhibits the comparable electrochemical catalytic activity to the commercial Pt/C. For NHCS-Fe, its ORR half-wave potential in neutral and alkaline media is 0.78 V and 0.83 V respectively. Corresponding neutral Zn-air battery reveals a maximum power density of 118.8 mW·cm−2, while they are respective 0.82 V and 46.99 mW·cm−2 for Pt/C. Alkaline Zn-air battery with NHCS-Fe releases a maximum power density of 262.4 mW·cm−2, displaying superior performance to Pt/C. Our work is instructive for the synthesis of novel ORR catalysts with outstanding activity by a versatile synthesis strategy.