Functional properties of electrospun NiO/RuO2 composite carbon nanofibers

One-dimensional (1D) nickel oxide/ruthenium oxide (NiO/RuO2)–carbon composite nanofibers (NiRu–C–NFs) were fabricated via electrospinning of a homogenous mixture of polyacrylonitrile (PAN) and Ni/Ru salt precursors at different ratios followed by heat treatments. The 1D nanostructures of the composite material were characterized by field-emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), Rietveld refinement and Brunauer–Emmett–Teller (BET) surface area measurements. Li-cycling properties were evaluated using cyclic voltammetry and galvanostatic properties. The asymmetric hybrid supercapacitor studies were carried out with activated carbon as a cathode and NiRu–C–NFs composites as anodes in the cycling range, 0.005–3.0 V using 1 M LiPF6 (EC;DMC) electrolyte. NiRu–C–NFs fabricated from 5 wt% nickel (II) and 15 wt% ruthenium (III) precursors showed a capacitance up to ∼60 F g−1 after 30 cycles. Anodic Li-cycling studies of NiRu–C–NF-0 and NiRu–C–NF-2 composite samples showed a reversible capacity of 230 and 350 m Ahg−1 at current rate of 72 mA g−1 at the end of 40th cycle in the voltage range of 0.005–3.0 V. Electrochemical impedance studies (EIS) on NiRu–C–NFs showed lower impedance value for 15 wt% Ru than the bare sample.

► Fabrication of carbon nanofibers with nickel–ruthenium composites by electrospinning.
► An interesting observation of increase in capacitance with increase in the number of cycles for supercapacitor applications.
► Li ion battery testing showed a stable capacity ranging from 350 mAh g−1 to 400 mAh g−1.
► Lower impedance with the incorporation of 15 wt% Ru precursor than those without Ru.