Co 0.7 Fe 0.3 NPs confined in yolk-shell N-doped carbon: engineering multi-beaded fibers as an efficient bifunctional electrocatalyst for Zn-air batteries

• Published in: Nanoscale Vol. 13; no. 4; pp. 2609 - 2617
• Main Authors: Long, Ling, Liu, Haohui, Jia, Jianbo, Zhang, Yelong, Dong, Shaojun
• Format: Journal Article
• Language: English
• Published: England 04.02.2021
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/D0NR08781E

The development of bifunctional catalysts with a delicate structure, high efficiency, and good durability for the oxygen evolution reaction (ORR) and oxygen evolution reaction (OER) is crucial to renewable Zn-air batteries. In this work, Co Fe alloy nanoparticles (NPs) confined in N-doped carbon with a yolk-shell structure in multi-beaded fibers were prepared as a bifunctional electrocatalyst. The confinement structure was composed of an N-doped graphitized carbon shell and a core formed by numerous Co Fe NPs, and was evenly threaded into a one-dimensional fiber. Moreover, this distinctive hierarchical structure featured abundant mesopores, a high BET surface area of 743.8 m g , good electronic conductivity, and uniformly distributed Co Fe /Co(Fe)-N coupling active sites. Therefore, the experimentally optimized Co Fe @NC -800 showed excellent OER performance (overpotential reached 314 mV at 10 mA cm ) that far exceeded RuO (353 mV), and good ORR catalytic performance (half-wave potential of 0.827 V) comparable to Pt/C (0.818 V). Impressively, the Co Fe @NC -800 Zn-air battery delivered a higher open circuit voltage of 1.449 V, large power density of 85.7 mW cm , and outstanding charge-discharge cycling stability compared with the commercial RuO + 20 wt% Pt/C catalyst. This work provides new ideas for the structural design of electrocatalysts and energy conversion systems.