Facile binder-free hydrothermal synthesis of NiCo2O4 using different reagents: a study as efficient supercapacitor electrode.

In the present study, mesoporous NiCo2O4 nanomaterials were successfully synthesized on nickel foam using an eco-friendly, facile, cost-effective and reagent-assisted hydrothermal method. The physico-chemical properties were analyzed by XRD, RAMAN, FTIR and FE-SEM characterization and results confirmed the formation of NiCo2O4 nanoparticles. By employing cetyltrimethyl ammonium bromide (CTAB) and NH4F as auxiliary reagents, two different samples were synthesized and the resulting NiCo2O4 nanoneedle arrays achieved, efficient charge transport, excellent specific capacitance (357 F/g at 1 A/g current density for NCO-N and 403 F/g at 1 A/g for NCO-C), good energy and power density and strong rate capability. Electrodes were synthesized by applying these materials on nickel foam (1 × 1 cm2) and underwent electrochemical characterizations. An asymmetric supercapacitor was fabricated using NCO-C as positive electrode and Typha Angustifolia activated carbon (TAC) as negative electrode in 2 M KOH electrolyte. The device exhibited high energy density of 33.22 Wh/kg and power density of 400 W/kg at 0.2 A/g. A good capacitance retention of 92.83% after 5000 charge-discharge cycles at 0.2 A/g current density was achieved.