Electrochemical efficiency of carbon nanofiber/molybdenum oxide nanocomposites synthesized by electrospinning used in supercapacitors and oxygen evolution reaction

Supercapacitors are used as promising new systems with significant potential and capability for energy storage due to their high-power density and long-term cyclic stability. In this study, carbon nanofiber/molybdenum oxide (CNF/MoO3) nanocomposites, as supercapacitor electrode materials and electrocatalyst for oxygen evolution reaction (OER), were successfully synthesized by electrospinning method followed by a thermal treatment. The fabricated electrodes were accurately characterized via different techniques such as: X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). The characterization analysis confirmed the presence and uniform distribution of MoO3 nanocrystals in carbon fibers. Electrochemical investigation showed that increasing the weight percentage of MoO3 in carbon nanofibers enhances the specific capacitance of the produced nanocomposites, due to the pseudo-capacitance properties of ultrafine MoO3 nanocrystals. The capacitance values at a current density of 1 mA·cm−2 were 162 and 274 mF·cm−2 for nanocomposites with 15 wt% and 30 wt% of MoO3, respectively. The results of EIS studies indicated that by increasing the MoO3 content from 15 to 30 wt%, the charge transfer resistance (Rct) parameter decreased from 1.38 Ω to 0.6 Ω. Moreover, the addition of a higher weight percentage of MoO3 to the nanocomposites improved the electrocatalytic behavior of electrodes in OER process so that, the required overpotentials in 30 wt% MoO3 for reaching the current densities of 10, 30 and 100 mA·cm−2 were 311, 344 and 415 mV, respectively. Finally, the results indicated that CNF/MoO3 nanocomposites exhibit great potential as electrode materials for high-performance energy storage and conversion systems.