Synthesis and characterization of some transition metal oxides and their grapheme based composites as electrodes for supercapacitor applications

Abstract

The development of efficient energy storage device is the greatest challenge among researchers to cater the need of energy demand in modern applications Most recently supercapacitors have attracted much attention due to their high power density than batteries and high energy density than conventional capacitors Moreover supercapacitors have long life cycle flexible and easy to handle Pseudocapacitors have gained high platform than Electric double layer capacitors EDLC materials due to the faradaic type of energy storage This doctoral work has been carried out in the motivation to attain high specific capacitance and to improve energy and power density of ternary metal composites compared to its binary metal oxides The nanomaterials reported in this work are various spinel metal oxides and graphene nanocomposites as efficient electrodes for supercapacitors ZnMn2O4 and ZnMn2O4 rGO electrodes were prepared by hydrothermal method and investigations were carried out to examine their compatibility for supercapacitors Graphite oxide prepared by improved Hummers method has been exfoliated at low temperature and used for the synthesis of ZnMn2O4 rGO Successful formation of ZnMn2O4 and reduced graphene oxide incorporated ZnMn2O4 are identified from powder X ray diffraction patterns The X ray diffraction analysis revealed that ZnMn2O4 have spinel tetragonal crystal structure with average crystallite size calculated to be 18 nm whereas ZnMn2O4 rGO crystallite size calculated to be 20 nm Functional groups and vibrations present in the samples are confirmed using Fourier transform infrared spectroscopy and Raman spectroscopy X ray photoelectron spectroscopic analysis confirmed the oxidation states and atomic concentrations present in the surfaces of compound and composite From the deconvoluted high resolution spectra of C 1s the increase in peak intensity and the atomic weight percentage of carbon in ZnMn2O4 rGO than ZnMn2O4 confirmed the presence of rGO Morphological features of the synthesized ZnMn2O4 nanoparticles and rGO