A Comparative Cyclic Voltammetry Study of Amorphous Carbon-Transition Metal Oxide Hybrid System: Selection for the Best Capacitor

Abstract

The present study addresses the synthesis of various amorphous carbon nanostructures-transition metal hybrid systems by a simple, low-temperature chemical route. Electron microscopic images of the pure and hybrid systems confirmed that different functionalized samples have significantly different morphologies. The Fourier-transformed infrared spectroscopic analysis provided ideas about different bonds present in all the samples, whereas the Raman spectra quantified the carbon content with different hybridization states. Thermal analysis confirmed that all the samples are thermally well-stable. Whereas energy dispersive X-ray was used to perform quantitative еlеmеntal analysisWhen cyclic-voltammetry (CV) and galvanostatic charge-discharge (GCD) studies of all the samples were performed, it was seen that among all the hybrids, the manganese-based system gave the best result with specific capacitance values over 530F/g.When Nyquist plots of all the samples were done in order to study the electrochemical impedance spectra, it was confirmed that the manganese based system shows the ideal capacitive nature with the lowest value of internal resistance. It was seen that when a-CNTs were functionalized with MnO2, the specific capacitance increased almost 7 times, whereas other samples gave much inferior results. Efforts have been made to explain the variation of the results from the point of view of the fundamentals of electrochemistry. It has been shown that the change in surface area, porosity, ion transport, and clustering of the foreign nanostructures are the key parameters behind the result.