Study of Supercapacitive and Photocatalytic Properties of In2O3 based Nanostructures

Abstract

The growth and discovery of advanced electrode materials hold great promise for enhancing energy storage devices, such as batteries and supercapacitors, by providing superior energy density and high power density. Additionally, these materials play a crucial role in the field of photocatalysis, which is a process that uses light to initiate chemical reactions. These advancements can contribute to the development of cleaner and more powerful energy systems, ultimately benefiting various industries and the environment. Good performance of electrodes is typically achieved via ultrathin electrodes with low mass loadings, good electrical conductivity, two-dimensional spatial frameworks, high specific surface areas, porous structures, binder-free designs, and a cost-effective fabrication approach. In order to achieve these goals, a careful selection of electrode materials must be made. The pursuit of these advancements is crucial for advancing renewable energy technologies and addressing environmental challenges. In this thesis, a simple and facile chemical method has been employed for the synthesis of (In2O3)x/(CuO)1-x, (In2O3)x/(NiO)1-x, (In2O3)x/(Fe2O3)1-x, and (In2O3)x/(GNP)1-x heterostructure nanocomposites. These composite materials have been characterized in detail via XRD, SEM, TEM, EDX, UV-Vis, and IV spectroscopy to explore their structural, morphological, compositional, optical, and electrical properties. The morphological and compositional studies have confirmed that all the fabricated samples are nanomaterials with good purity and proper stoichiometric compositions. The optical band gap of In2O3-based nanocomposites has been successfully tailored towards the visible range with the addition of various additives in the composite formation. The electrochemical activities of the electrode’s materials based on prepared nanocomposites have been carried out in a half-cell setup of an electrochemical workstation. It has been interesting to find that the electrochemical results have shown that the cyclic stability, specific capacitance, and rate performance of In2O3-based nanocomposites with CuO, NiO, Fe2O3, and GNPs are significantly improved as compared to the pristine In2O3-based electrode material. xvii The specific capacitance (Csc) of prepared nanocomposite electrodes supported on nickel foam (NF) has been measured with a three-electrode system by the galvanostatic charge discharge (GCD). It has been observed that among all nanocomposites series, the particular (In2O3)0.5/(CuO)0.5, (In2O3)0.3/(NiO)0.7, (In2O3)0.3/(Fe2O3)0.7, and (In2O3)0.7/(GNP)0.3 nanocomposites have exhibited 883, 830.6, 945, and 1768 Fg-1 specific capacitance, respectively. Furthermore, (In2O3)0.3/(Fe2O3)0.7 nanocomposites have shown 93.6% rate capability, which is the highest among all prepared nanocomposites, even at large current density scales. According to the results of the cyclic stability study, the prepared nanocomposites with 92.2% cyclic charge discharge after 3000 cycles have shown excellent electrochemical stability compared to the pristine In2O3 nanomaterials with only 35% of their initial specific capacity after 3000 consecutive tests. These significantly enhanced electrochemical capabilities of the prepared nanocomposites are attributed to the tailoring of band structure, formation of interfacing defects, high specific surface area, and nanoarchitecture. The electrodes based on these nanocomposites are highly suitable for next-generation supercapacitors in advanced energy storage technology. The photodegradation of the most common toxic dyes present in industrial waste has been performed using prepared nanocomposites. All samples have exhibited good degradation against pollutants. The In2O3-GNPs nanocomposites have shown maximum (99.9%) solar light trigged degradation against these hazardous dyes, which is a significant achievement in overcoming the issue.