Interface engineering of Co3Fe7-Fe3C heterostructure as an efficient oxygen reduction reaction electrocatalyst for aluminum-air batteries

Aluminum-air batteries with merits of high theoretical energy densities, low cost and environmental-friendliness are promising candidates for next-generation energy storage and conversion systems. Rational design of efficient heterogeneous catalysts for oxygen reduction reaction (ORR) in neutral and alkaline solutions is of great significance for aluminum-air batteries. Herein, an interface engineering strategy is proposed to realize Co3Fe7-Fe3C heterostructure with abundant interfaces anchored on 3D honeycomb-like N-doped carbon, which inherits the original structure of the biomass precursor. The as-prepared Co3Fe7-Fe3C heterostructure on honeycomb-like N doped carbon (denoted as Co3Fe7-Fe3C/HNC) displays remarkable electrocatalytic activity and stability towards ORR in both alkaline and neutral solutions. It shows a very positive onset potential of 0.98 V and a half-wave potential of 0.90 V in 0.1 M KOH solution (E-onset = 0.78 V and E-1/2 = 0.64 V in 3.5% NaCl solution) towards ORR. The high ORR performance is mainly ascribed to the abundant engineered interfaces, which can not only boost the intrinsic activity, but also guarantee fast charge transfer. The superior ORR performance is also supported by the density functional theory calculation. Moreover, the fabricated Al-air battery displays a larger working voltage and a higher power density compared with those of Pt/C. Furthermore, the Co3Fe7-Fe3C/HNC catalyst exhibits outstanding stability and durability during mechanical recharging and continuous discharging processes. This work demonstrates a new strategy to design and construct multifunctional catalysts with interfacial structure for high performance metal-air batteries.

Automated summary

Aluminum-air batteries, with their high theoretical energy densities, low cost, and eco-friendliness, are potential candidates for next-generation energy storage and conversion systems. Rational design of efficient catalysts for the oxygen reduction reaction in neutral and alkaline solutions is crucial for the performance of these batteries. A new interface engineering strategy has been proposed to create a Co3Fe7-Fe3C heterostructure with abundant interfaces anchored on 3D honeycomb-like N-doped carbon, leading to remarkable catalytic activity and stability towards ORR. This work demonstrates a novel approach to designing multifunctional catalysts with interfacial structures for high-performance metal-air batteries.