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1D nanofibers with higher surface area, small pore size, high porosity, good electrical conductivity, and relatively high production rate with high fiber interconnectivity have gained attention as energy materials. In the present study, citrate-stabilized 1D cobalt oxide nanofibers are prepared by the electrospinning technique using polyvinylpyrrolidone (PVP) polymer followed by annealing at 500 °C where PVP acts as the carbon source leading to highly porous 1D Co3O4@C nanofibers exhibiting enhanced specific capacitance. Microscopic and structural characterization illustrates that the rod-shaped Co3O4 is interlinked with each other through polymer-derived carbon in the form of a nanofiber network. The electrospun Co3O4@C nanofibers demonstrate a specific capacitance of 731.2 F g–1 at a current density of 8 A g–1 in the 0.1 M KOH electrolyte. Furthermore, the Co3O4@C nanofibers show better cyclic stability with an excellent capacity retention of 100% after 3000 continuous GCD cycles at a current density of 9 A g–1. Again, the asymmetric supercapacitor system with the PVA–KOH electrolyte was fabricated and showed a specific capacitance of 120. 8 F g–1 (12.08 mF cm–2) with an energy density of 37.75 Wh kg–1 (3.77 mWh cm–2) and power density of 1800 W kg–1 (180 mW cm–2) at 0.6 A g–1 (0.06 mA cm–2) current density. The symmetric supercapacitor shows 100% retention in specific capacitance after 4000 GCD cycles. The enhanced supercapacitor performance of 1D Co3O4@C nanofibers was attributed to their unique nanofibrous structure with greater active surface area provided by the in situ carbon, facilitating a faster ion and electron transfer.

A facile route for the development of a conducting hybrid polymer nanocomposites composed of poly(methyl methacrylate) (PMMA)/high density polyethylene (HDPE) filled with multiwall carbon nanotube (MWCNT) and expanded graphite (EG) has been described. The EG used in this study was prepared by simple chemical exfoliation of graphite flakes and characterized by spectroscopic as well as morphological analysis. An industrially feasible melt mixing process was used for the preparation of the nanocomposites through sequential heating protocol. The judicious control of temperature during mixing revealed a highly co-continuous structure of HDPE throughout the PMMA matrix and thus the percolation of the (75/25, w/w) PMMA/HDPE/bi-filler nanocomposites was achieved at 0.07 wt% loading of MWCNT. An extensive analysis revealed that the selective dispersion of the conductive bi-filler in the minor HDPE phase helped in the reduction of the percolation threshold through MWCNT-EG-MWCNT networking. The morphology, electrical conductivity, and their interrelation of the prepared nanocomposites can be found in detail in the manuscript. POLYM. COMPOS., 37:2070-2082

For energy storage applications, sulfur was in situ synthesized and encapsulated inside carbon fibers by using waste cotton textiles as the fiber template.

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