Preparation of CoFe2O4-Doped TiO2 Nanofibers by Electrospinning and Annealing for Oxygen Electrocatalysis

In this paper, catalyst precursor fibers were prepared by a sol gel method combined with an electrospinning method using tetrabutyl titanate as a titanium source, cobalt acetylacetonate as a cobalt source, and iron acetylacetonate as an iron source. CoFe@TiO2 nanofibers (NFs) with a bimetallic spinel structure were formed after thermal annealing, which have dual-functional catalytic activity. With the molar ratio of Co and Fe coming to 1:1, a typical spinel CoFe2O4 structure was generated in Co1Fe1@TiO2 NFs. At a load of only 28.7 μg·cm-2, Co1Fe1@TiO2 NFs not only have a low overpotential (284 mV) and Tafel slope (54 mV·dec-1) in the oxygen evolution reaction but also show a high initial potential (0.88 V) and limiting current density (6.40 mA·cm-2) in the oxygen reduction reaction. Meanwhile, Co1Fe1@TiO2 NFs exhibit good durability, cycle stability, and dual-function catalysis.