Remarkable capacitive behavior of a Co3O4-polyindole composite as electrode material for supercapacitor applications

In this paper, we demonstrate a single step synthesis of cobalt oxide - conducting polyindole (Co3O4-Pind) composites by in-situ cathodic electrodeposition. The structural and morphological changes of the as-prepared Co3O4-Pind composites have been investigated using various techniques such as powder Xray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman analysis and X-ray photoelectron spectroscopy (XPS). Very interestingly, polyindole decoration over Co3O4 results in concomitant change in morphology leading to substantial improvement in the supercapacitor behavior. The electrochemical performance of Co3O4-Pind has been investigated by cyclic voltammetry, galvanostatic charge-discharge cycling and impedance analysis. The specific capacitance (SC) of Pind decorated Co3O4 is found to be 1805 F g (1) at a current density of 2 A g (1) with excellent rate capability (SC: 1625 F g(-1) at a high current density of 25 A g(-1)) and cycling stability. This remarkable supercapacitive performance of the Co3O4-Pind composite is mainly attributed to the synergism that evolved between Co3O4 and Pind. More importantly, these electrodes are free from binders and conductive carbon which have significant impact over the gravimetric energy density of the devices.