Bacterial-cellulose-derived carbon nanofiber-supported CoFe2O4 as efficient electrocatalyst for oxygen reduction and evolution reactions

•Bacterial-cellulose-derived CNF-supported CFO has been facilely synthesized.•The as-prepared CFO/CNF is an efficient electrocatalyst for both ORR and OER.•The covalent coupling between CFO and CNF contributes to the high activity.•Improved electronic conductivity and mass transport contribute to the high activity.

Exploration of cost-effective electrocatalysts with high catalytic activity toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a key challenge in the development of metal-air batteries. In this study, bacterial-cellulose-derived carbon nanofiber-supported CoFe2O4 (CFO/CNF) has been prepared via a facile and green method. The three dimensional (3D) interconnected CNF network support with high surface area not only provides high electronic conductivity but also promotes the mass transfer of O2 and electrolyte during the ORR and OER. Furthermore, the strong coupling between CFO and CNF allows for fast charge transfer, facilitating the electrocataltyic processes. These lead to the high electrocatalytic activity of as-prepared CFO/CNF nanocomposite toward both the ORR and OER, outperforming CFO and CNF, respectively. Meanwhile, the stability of CFO/CNF nanocomposite toward the ORR and OER is much higher than that of benchmark Pt/C (20 wt.%) and RuO2/C (20 wt.%), respectively.

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