Electrospun cobalt Prussian blue analogue-derived nanofibers for oxygen reduction reaction and lithium-ion batteries

Electrospinning is an effective technique to fabricate one-dimensional materials. In this study, cobalt-embedded carbon nanofibers (Co@CNFs) are obtained via carbonization of electrospun cobalt Prussian blue analogue (Co-Co PBA) under nitrogen atmosphere. The Co@CNFs have metallic cobalt surrounded by graphitic carbon shells and possess high specific surface area, rich porosity, high graphitic degree, and rational nitrogen doping. The structure merits endow them with excellent electrocatalytic performances for oxygen reduction reaction (ORR): an onset potential of 0.867 V vs. RHE and 0.784 V vs. RHE at j =  - 3 mA cm^-2 with a four-electron transfer process. Through a further mild oxidation process, we obtain Co₃O₄ nanoparticles-embedded nitrogen-doped carbon (Co₃O₄@CNFs) with spindle-like morphology. When working as the anode materials for lithium-ion batteries (LIBs), Co₃O₄@CNFs show high specific capacity, good stability, and excellent rate capability. The Co₃O₄@CNFs anode delivers a discharge specific capacity of 1404 mA h g^-1 after 100 cycles at a current density of 100 mA g^-1 and about 500 mA h g^-1 after 500 cycles at 2000 mA g^-1. The diffusion- and capacitive-controlled processes both contribute to the charge storage of the Co₃O₄@CNFs electrode. This study provides a new strategy to fabricate the excellent electrocatalysts for ORR and anode materials for LIBs via facile electrospinning.