NiCo₂O₄-decorated porous carbon nanosheets for high-performance supercapacitors

A facile hydrothermal method is invoked for direct template-free synthesis of nickel cobaltite (NiCo₂O₄)-decorated porous carbon nanosheets using polymeric 3,4-ethylenedioxythiophene (EDOT) as the precursor. The nanocomposite materials (named as NC-ECN) so fabricated were characterized by a variety of different techniques (viz. SEM/TEM, XPS, EDX etc.). These novel NC-ECN nanocomposites, which exhibit flower-like morphology and excellent electrochemical properties such as good electric conductivity and redox properties, high specific capacitance, excellent rate capability and cyclability, are shown to be desirable for high-performance pseudosupercapacitor applications. On the basis of cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements, the NC-ECN modified electrode was found to exhibit a maximum specific capacitance of 596.8 F g⁻¹ measured at a current density of 2 A g⁻¹ over an aqueous 6.0 M KOH electrolyte solution. Moreover, the fabricated supercapacitor is also found to have excellent cyclability, retaining ca. 98% of its capacitance over more than 3,000 charge-discharge cycles. The excellent pseudocapacitive performances observed for the NC-ECN electrode results are attributed to the synergistic effect of redox characteristics of binary metal oxide and the improved electric conductivity of the porous ECN carbon nanosheets, which effectively enhances kinetics of ion diffusion.