An Investigation on the Supercapacitive Performance of CuCo2O4/Polyaniline, a Nanocomposite of Spinel Structured Transition Binary Metal Oxide and Conducting Polymer, with a Special Focus on Bonding and Electron Density Distribution Through MEM

Abstract

CuCo2O4 nanomaterial was synthesized by cost effective, time saving combustion route and a composite material CuCo2O4/PANI was prepared by physical blending. X-ray diffractometer studies were used to characterize the structural properties of synthesized nanoparticles thereby confirming the appearance of cubic spinel phase with the crystallite size ranging from 10 to 40 nm. Rietveld refinement method was used to derive density of nanoparticles, unit cell volume and other parameters. Fourier transform infrared spectroscopy was used to confirm the functional groups as well as the presence of vibrations in the samples which is in accordance with XRD results. The distribution of electron density and chemical bonding were studied through maximum entropy method. The changes in these factors in pure and composite have demonstrated improved electrochemical behavior of the latter. The crystallite size and lattice strain were calculated by Williamson–Hall (W–H) analysis, and size-strain plot method (SSP) that was in correlation with that of Scherrer method. Findings from SSP method, Scherrer and HR-TEM results were well matched. The morphology of synthesized nanoparticles of pure and composite were examined through FE-SEM and HR-TEM images. The morphological changes have proved improved electrochemical capability of the composite. The morphological observations of FE-SEM and HRTEM were in good accordance. The crystalline property of the materials is confirmed from SAED patterns of HRTEM that matched well with the XRD study. The electrochemical characterization of the samples was carried out by CV and CP observations. The composite material CuCo2O4/PANI exhibited a higher maximum specific capacitance of 659 F/g at 5 mV/s scan rate in comparison with 515 F/g exhibited by pure CuCo2O4 as calculated from CV. The higher performance of the composite material is also evident by the electrochemical impedance study, as the resistance was lower than the pure. The ESR of the composite was 3.52 V and that of pure was 5.93 V, as obtained from the Nyquist plot. On the basis of outcome of the results, CuCo2O4/PANI nanocomposite displays better performance when compared to the pure CuCo2O4. This has been achieved by low cost, time saving and simple synthesis method.