A “Ship-in-a-Bottle” strategy to anchor CoFe nanoparticles inside carbon nanowall-assembled frameworks for high-efficiency bifunctional oxygen electrocatalysis

Abstract

Elaborate design of cost-effective and highly-efficiency bifunctional electrocatalysts towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critically essential for the advancement of rechargeable metal-air batteries. Herein, we develop a straightforward and scalable hydrogel-bridged pyrolysis strategy for the exquisite construction of a “ship-in-a-bottle”-structured bifunctional catalyst consisting of fine CoFe nanoparticles encapsulated inside the carbon nanowall-assembled frameworks (abbreviated as [email protected] hereafter). The deliberate design of such intriguing hierarchical honeycomb-like architecture with tightly confined CoFe nanoparticles and open configuration endows the as-fabricated [email protected] with sufficient well-dispersed active sites, rapid charge transfer efficiency, accelerated mass diffusion and robust mechanical strength. Consequently, the resultant [email protected] catalyst shows outstanding catalytic performance toward the ORR and OER with high activity and long-term stability. More encouragingly, a rechargeable Zn–air battery using [email protected] as the air cathode displays superb energy density, high energy efficiency and robust reversibility, surpassing the state-of-the-art precious Pt/C + RuO2–assembled counterpart. The developed methodology for the fabrication of “ship-in-a-bottle” architectures may open new opportunities to low-cost, mass production of high-efficiency bifunctional oxygen electrocatalysts for a variety of renewable energy technologies and beyond.