Browsing by Author "Sabrina. Iaiche"

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    Effect of ZnO Nanoparticles Salt Precursors on Structural, Morphological, Optical and MB Photocatalytic Properties Using Hydrothermal Synthesis
    (2023-03-30) Sabrina. Iaiche
    Zinc oxide ZnO nanoparticles were successfully produced via a simple low cost hydrothermal method using different metal precursors. Zinc acetate Zn(CH3COO)2, Zinc nitrate (Zn(NO3)2) and Zinc chloride (ZnCl2) were the source materials. The obtained nanoparticles were investigated by means: X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Differential Reflectance spectroscopy (DRS). The XRD exhibited the high crystallinity of the pure ZnO phase with hexagonal wurtzite crystalline structure for all simples excepted for ZnO synthetized from ZnCl2 precursor. The crystallite sizes were estimated in the range of 20-37 nm. The precursor type does not affect the Eg of the nanoparticles. The bandgaps energies were between 3.21-3.22eV. The type of precursor affect the particles morphology. SEM images reveal different morphologies. The photocatalytic activity of the synthetized ZnO (zinc oxide) ( NPs, in comparison with that of commercial powder for the methylene blue (MB) degradation under Ultra-Violet (UV) irradiation, showed the appropriate activity of nanostructures obtained by Zn(NO3)2 and Zn(CH3COO)2 precursors. The first-order kinetic constant over ZnO from Zn(NO3)2 was 1.9, 3.7 and 1.5 times of ZnO commercial powder, ZnO from ZnCl2 and Zn(CH3COO)2, respectively. The ZnO NPs from Zn(NO3)2 and Zn(CH3COO)2 precursors have the best photocatalytic degradation performance with a degradation rate of 99.3% and 96.4%, respectively. It is found that the higher photocatalytic performance was probably due to the larger crystallinity, purity phase and specific morphologies than smaller particle size effect. A decrement in the crystallite size yields in a larger surface areas and enhances the adsorption of reactants and that paves the way to an enhancement in the photocatalytic performance. Thus, the synthetized ZnO is nanoparticles by the soft hydrothermal process which is a promising candidate for the photocatalytic purposes of dyes from waters
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    Facile synthesis and characterization of ZnO:Al/ZnS/NiO heterojunction thin films with enhanced photocatalytic activities
    (2023) Sabrina. Iaiche
    This study covers a physical investigation of ZnO:Al/ZnS/NiO heterojunction thin films and their photocatalytic activities. The obtained samples were analyzed using XRD, FTIR, SEM/EDS, AFM, and UV–vis spectroscopy. The XRD and FTIR results confirmed that the nanocrystalline ZnO, ZnS, and NiO phases were successfully prepared. SEM morphological analysis of the multilayer film indicated that depositing different nanocrystalline layers above one another could deteriorate the adherence of the upper layer. In addition, AFM shows acceptable surface roughness for application as a photocatalyst. Optical analysis revealed that the ZnO:Al/ZnS/NiO multilayer film exhibited an average transmittance of 65%. The Eg value of the ZnO:Al monolayer of 3.26 eV is decreased to 3.15 eV after Al–ZnO/ZnS coupling, whereas ZnO:Al/ZnS/NiO exhibits an additional absorption value of 3.52 eV due to the NiO layer. The photocatalytic activity of ZnO:Al/ZnS/NiO under visible light exhibited an approximately 96% photodegradation efficiency against methylene blue after only 50 min. However, under sunlight, the degradation rates reached 90, 85, and 65% for methylene blue, crystal violet, and Congo red, respectively, in 90 min. This study shows that a synthesized ZnO:Al/ZnS/NiO heterojunction multilayer photocatalyst can efficiently degrade organic pollutants.