CeO2 quantum dots embedded in 3D hierarchical porous foliaceous N-doped carbon as an efficient oxygen reduction electrocatalyst for metal-air battery

The development of large-scale and highly efficiency catalysts towards oxygen reduction reaction (ORR) is of great significance for the wide application of metal–air batteries. In this work, we propose a self-sacrifice template method combined with in-situ composite technique to fabricate a novel configuration of CeO2 quantum dots embedded in hierarchical porous foliaceous N-doped carbon with both mesopores and micropores. The prepared catalyst exhibits prominent ORR electrocatalytic performance with higher half-wave potential, lower Tafel slope, and enhanced durability comparing with the commercial Pt/C catalyst. Furthermore, the Zn-air and Al–air batteries employing the prepared electrocatalysts in cathodes exhibit superior discharge performance with high open circuit voltages of 1.51 V and 1.76 V, and peak power densities of 204 and 458 mW cm−2, respectively, compared to most reported metal–air batteries. The greatly enhanced electrocatalytic performance can be ascribed to the abundant oxygen vacancies, improved redox property of Ce3+/Ce4+ as well as the three-dimensional hierarchical porous structure. This work provides a valuable chance to develop scalable quantum dot level composite catalysts in metal–air batteries.