Nickel Cobalt Oxide Nanoparticles Decorated MWCNTs as Stable and Improved Supercapacitor Electrode Material

Abstract

A simple wet chemical route involving ultrasonication is used in this work for the insitu decoration of NiCo2O4 on the surface of carbon. The NPs of NiCo2O4 are synthesized via same route. Nickel acetate tetra-hydrate and cobalt acetate tetra-hydrate are used as metal precursors. MWCNTs counts for the carbonaceous moiety in the resulting hybrid of the two materials. Polyethylene glycol (PEG 6000) is used as a capping agent along with dimethyl formamide as solvent for the synthesis process. The morphology of the NPs is examined through scanning electron microscopy. The capping agent successfully capped the NPs size in an average diameter of 23 nm. The crystal structure of the resulting NPs and composite is characterized by X-ray diffraction (XRD). Formation of a cubic structure of NiCo2O4 is confirmed. Elemental analysis of the materials is performed via EDS to investigate the percent weight of constituent elements in both NiCo2O4 NPs and its nanocomposite with carbon. The electrochemical analysis of the materials is done via cyclic voltammetry and galvanostatic charge discharge tests. A typical three electrode system is used for the electrochemical measurement in a 2 M KOH electrolyte. A high specific capacitance of 1788 F/g is obtained for the composite of NiCo2O4@MWCNTs. The specific capacitance of NPs of NiCo2O4 is found to be 1442 F/g. cyclic stability test conducted revealed that the composite material retain 96 % of the performance after 1000 cycles of charge discharge. The NiCo2O4 @NPs retained an efficiency of 89 % after 1000 charge discharge cycles.