Browsing by Author "LHR TP 7265"

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    Synthesis and Characterization of Metal Doped Kesterite (Cu2ZnSnS/Se) Derived Nanostructures as Light Absorber for Thin Film Solar Cell Applications
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Muhammad Yasir Yaqoob; CIIT/FA19-RPH-038/LHR; Dr. Samia Aslam; LHR TP 7265
    Kesterite materials (Cu2ZnSnS/Se or CZTS) exhibit encouraging potentials for energy conversion. In this study inexpensive, and cost-effective kesterite-derived nanostructures through metal doping in (CuZnXS, X=Ce, La, Mo) has been synthesized and test them as photo-absorbing materials for semiconductor-based thin- film solar cell applications. The photo-absorbance or light-absorption propensity of the photo-anode material in a solar cell is essential to the overall effectiveness of the solar cell. By adding a second layer of photo absorbance material, the photo-anode activity can be increased, which may also increase the amount of photogenerated electrons. Optical spectroscopy methods, such as UV-visible spectroscopy, is used to examine the photo absorption characteristics of the synthesized nanostructures. The optical band gap, % transmittance, extinction coefficient and refractive index of the kesterite material has been calculated and it was found that the band gap of the as synthesized kesterite material is varies in the range 1.125eV -1.5eV which is suitable as the absorber material for solar cell applications. The structural defects and recombination centers are examined using Photoluminescence spectroscopy. X-ray diffraction (XRD) and Raman Spectroscopy has been done to study the structure parameters and vibrational modes of the as synthesized kesterite material. The XRD patterns of the materials shows the formation of kesterite material with tetragonal structure for Ce-CuZnS and Mo-CuZnS and kesterite with monoclinic structure for La-CuZnS. The Raman spectra of all samples shows the characteristics modes of Cu- S, Zn-S and Ce2O, La-O and different modes of S-Mo-S in Ce-CuZnS, La-CuZnS, and Mo-CuZnS respectively.
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    Synthesis of Gd Doped Ni-Ferrites and their Photocatalytic Degradation of Methylene Blue Under UV-Visible Irradiations
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) MUHAMMAD DILSHAD; CIIT/ FA19-RPH-038/LHR; Dr. Muhammad Hammad Aziz; LHR TP 7265
    A good approach for the photodegradation of Methylene Blue (MB) dye under UV-Visible irradiation is the use of Gadolinium-doped Nickel-Ferrites as a photocatalyst that showed the high photocatalytic activity, highly magnetic separability and cost-effective results. The nanoparticles of Gadolinium-doped Nickel-Ferrites (NiGdxFe2-xO4, x=1 %, 3 %, 5%) were prepared by using hydrothermal synthesis route. The structural and morphological properties of the synthesized nanoparticles studied by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), Energy dispersive spectroscopy (EDX), UV-visible spectroscopy, and Photoluminescence (PL). The structural morphology showed that prepared samples are uniform. The structural properties confirmed to be in good agreement for both XRD, and SEM results and confirmed the cubical nature of the prepared spinel. Furthermore, the increase in size of the nanoparticles with increase in Gd3+ contents, confirmed from the diffraction peaks and SEM analysis. The size of crystallites ranged in 42-48nm evaluated by using Debye-Sharrer’s formula from more intense diffraction peak. The composition of the prepared specimen confirmed by Fourier transform infrared spectroscopy (FTIR), that showed to sharp absorption bands from 400 cm-1 and 600 cm-1.Photocatalysis carried out to check the photocatalytic activity of the synthesized nanoparticles having different concentrations of Gd3+, for the degradation of Methylene Blue (MB) dye under UV-Visible light. The photocatalytic activity checked, resulted 8%, 27%, 41% and 80% for host nickel ferrites and Gd doped nickel ferrites respectively, for the degradation of Methylene Blue (MB) dye under UV-Visible irradiation only in 50 mins, it is concluded that the photocatalytic activity increased by increasing reaction time and the concentration of Gd3+ in nickel ferrites, and this can be increased up to 80 %. The prepared nanoparticles (nickel ferrites with various Gd3+ contents) attested to be cost effective, eco-friendly, reusable after recycling, high magnetic separability after use, and high photocatalytic activity for the photodegradation of Methylene Blue (MB) dye under UV-Visible irradiation.