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Novel unique fabrication of ZnO nanoparticles decorated graphene beaded carbon nanofibers (G-CNF) encapsulated by polyaniline (PANI) nanocomposites through three steps by electrospinning, hydrothermal and in-situ polymerization is reported. As-synthesized G-CNF/ZnO/PANI and CNF/ZnO/PANI nanocomposites were comparatively studied by scanning electron microscopy and electrochemical characterizations for supercapacitor application. Electrochemical measurements of G-CNF/ZnO/PANI electrode revealed the maximum specific capacitance, discharge time, energy density and power density as compared to that of CNF/ZnO/PANI indicating the increase in surface area due to graphene incorporation in electrospinning of carbon nanofibers. The combination of electric double layer charge (EDLC) capacitance from high surface area of G-CNF and pseudo-capacitance from PANI and ZnO nanoparticles facilitates the synergistic effect of ternary components to enhance the electrochemical performance of G-CNF/ZnO/PANI nanocomposite.

A green and sustainable approach to recycle the waste iron rust into a valuable α modification of Fe2O3 via simple grinding and calcination for application in hybrid supercapacitor is reported. The α-Fe2O3 was coupled with conducting polymer carbon nanofibers (CNF) and Poly aniline (PANI) to form composite hybrid supercapacitor electrode materials. The conventional hydrothermal, electro-spinning processes were used to prepare composites. X-ray diffraction, Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED), Scanning Electron Microscopy and Energy Dispersive X-Ray spectroscopy were used to study the structural, morphological and compositional properties of as synthesised α-Fe2O3 and its composites with CNF and PANI. The α-Fe2O3/CNF and α-Fe2O3/PANI composites coated on carbon rod were used as electrodes in a three-electrode system to study Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Galvanostatic Charge-Discharge in 1M H2SO4. It is observed that α-Fe2O3/PANI exhibit higher response as against α-Fe2O3/CNF with respect to specific capacitance; 192.29 Fg-1 (88.88 Fg-1), energy density; 11.28 WhKg-1 (3.084 WhKg-1) power density; 162.44Wkg-1 (69.39 Wkg-1) with capacitance retention of 80% (75%). The heavy dispersion of α-Fe2O3 over long CNF and PANI fibres with intimate contact resulted in abundant active sites for electrochemical reactions leading to obtained result. The rust derived α-Fe2O3 with PANI offer excellent stability to act as potential candidate for sustainable hybrid supercapacitor application.

In this paper, we report the fabrication of activated carbon nanofibers/cobalt ferrite (CNF/CoFe2O4) composites by electrospinning and hydrothermal methods for comparative study of electrochemical properties. The structural, morphological and compositional analyses of the synthesized composites were examined using x-ray diffraction, scanning electron microscopy and energy dispersive x-ray spectroscopy. CNF/CoFe2O4 electrodes were investigated for electrochemical behavior using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). The results showed that hydrothermally synthesized CNF/CoFe2O4 composite exhibited the specific capacitance 188.36 Fg−1, whereas electrospun CNF/CoFe2O4 composite resulted the specific capacitance 106.59 Fg−1 at lowest current density 0.5 Ag−1. 80% capacitance retention of CNF/CoFe2O4 prepared by hydrothermal as compared to 60% capacitance retention of CNF/CoFe2O4 prepared by electrospinning. These results concluded that CNF/CoFe2O4 electrode obtained by hydrothermal exhibited comparatively excellent electrochemical performance and found its suitability as electrodes for supercapacitors.