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Item First principal studies of optoelectronics and thermoelectric properties of doped solid state hydrides material for hydrogen storage applications(UMT, Lahore, 2023) Madiha Masood MakhdoomHydrogen is considered as potential energy carrier for mobile and stationary storage use. However, the main issue is practical hydrogen storage material for use as fuel. Solid state hydrides offer high hydrogen storage capacity and show improvements both in volumetric and gravimetric capacity. But there is limited knowledge on hydrogen absorption mechanism and composition of material after release of hydrogen. Obtaining a detailed understanding of the relations between crystallographic structure of solid state materials and hydrogen storages are requirement for a possible guided search. Then design of similar transportation in the future. And detailed experimental transportation information of the electronic structure of solid state hydride has not been studied so far. Herein our thesis we will focus on metal hydrides, such as MgH2, NaAlH4, LiAlH4, LiH, LaNi5H6, TiFeH2 and other Metal hydride and will study its properties as a parental material and also by doping it with different dopants. The dopants we use depends upon the facts how it will affect the band gap of material understudy. So, in order to characterize hydride states responsible for transportation properties of Hydrogen storage materials relevant for technology; we use computational approach. This goal will be achieved by WIEN2K as well as BoltzTraP code which will allow us to simultaneously access the valence-band electronic structure as well as core level states.Item A first-principles study of spinel compounds for optoelectronics and thermoelectric applications(UMT, Lahore, 2023) Asif NadeemIn this thesis, the optical properties and electronic structure approximation have been discussed comprehensively via implementing Density Functional Theory (DFT). Advancements in optical devices and telecommunication have increased the demand for composition with high optical coefficients. For this, several items with appropriate optical properties have been developed, some of which are based on the family of spinel compounds. Their flexibility in various construction and structure allows for the adjustment of their visual structures. Lithium ion battery has gained popularity due to the suitability of many technological applications. Recently, the LiMn2O4material has been used widely due to their improved optoelectronic properties. Spinel Compounds have potential applications in electrical and optoelectronics fields. We explore the optical and electronic properties of Li1-xNixMn2O4 where (x= 0.04 % and 0.08%) are calculated through first-principle method based on the approximation known as the GGA+U, where U is the Hubbard parameter. The generalized gradient approximation (GGA) and local density approximation (LDA) do not treat properly the transition metal. Therefore we have used the GGA+U. The band gap dependent optical characteristics such as dielectric constant, optical conductivity, refractive index and reflectivity are calculated and examined. The substitution of the cation is examined and investigated for the studied compound and a prominent change is noticed. The reinforcement of the cation percentage of Ni decreases the band-gap and its dependent optical characteristics. In different regions of the spectrum for device fabrication this alteration is highly recommended.Item Synthesis of graphene based nanocomposites for biosensing and biomedical application(UMT, Lahore, 2023) Saira ShaheenThe exceptional properties of Graphene make it a compelling choice for nanomaterial applications. However, the combination of Graphene with other nanomaterials in the form of Nanocomposites (NC) opens up new possibilities for the fabrication and exploration of novel materials. In this thesis we focus on a specific set of Graphene-based nanocomposites that incorporate transition metal oxides. These nanocomposites offer a unique combination of Graphene's remarkable features with the desirable properties of transition metal oxides, providing a platform for the development of advanced materials with enhanced functionalities. As a start-up, GO-ZnO (Graphene Oxide-Zinc Oxide) nanostructures were successfully synthesized using the co-precipitation method with various concentration of GO. Characterization of designed NC was carried out using multiple techniques, while also evaluating their photocatalytic capability. XRD analysis confirmed the plane orientation and interplanar distance, which were consistent with the results obtained from HRTEM. Photoluminescence (PL) analysis clearly revealed a blueshift in the energies associated with near-band edge (NBE) emissions, indicating the impact of dopant quenching. The results suggested the uniform loading of dopant due to efficient coupling. This interface coupling enabled direct electron transfer from the valence band of ZnO to GO. The facile NCs demonstrated excellent photoactivity, offering a promising avenue for the design of next generation Graphene-based semiconductor composites. Furthermore, the synthesized samples exhibited remarkable bactericidal performance against both gram-positive (G +ve) and gram-negative (G -ve) bacteria, including S. aureus and E. coli, respectively. The antibacterial activity was confirmed through in vitro studies. Molecular docking analysis further provided insights into the mechanisms underlying the bactericidal activity of GO-ZnO nanostructures, suggesting the inhibition of β-lactamase and DNA gyrase as potential mechanisms. These findings contribute to a better understanding of the antibacterial properties of GO-ZnO nanostructures and their potential applications in combating bacterial infections.