Yazar "Elsayed, Khaled" seçeneğine göre listele

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    Enhanced photocatalytic degradation of methylene blue by nanocomposites prepared by laser ablation of Bi on CNT-a-Fe2O3 nanoparticles
    (Elsevier Sci Ltd, 2022) Manda, Abdullah A.; Elsayed, Khaled; Gaya, Umar İbrahim; Haladu, Shamsuddeen A.; Ercan, İsmail; Ercan, Filiz; Alheshibri, Muidh
    The low conductivity and high combination rate of photogenerated electrons (e-) and photogenerated holes (h+) are the real challenges of photocatalysis. These problems could be mitigated by the synthesis of heterostructured nanocomposites (NCs). In this study, Bi@CNT-Fe2O3 nanocomposite was fabricated via pulsed laser ablation in liquid and characterized by UV-Vis spectroscopy, photoluminescence (PL), X-ray diffraction (PXRD) and field scanning electron microscopy (FESEM). These techniques revealed successfully the formation of CNT-alpha-Fe2O3 and Bi@CNT-alpha-Fe2O3 nanocomposites. The photocatalytic activities of the Fe2O3, CNT-alpha-Fe2O3, and Bi@CNT-Fe2O3 photocatalysts were evaluated by the degradation of methylene blue (MB) dye under ultraviolet (UV) light irradiation in the presence of a very low concentration of hydrogen peroxide (H2O2) as an oxidizing agent. The results show that the Bi@CNT-alpha-Fe2O3 NC has the highest photocatalytic degradation efficiency of MB which completes in 20 min of UV light irradiation. In addition, the obtained rate constants (min-1) of Bi@CNT-alpha-Fe2O3 NC were 1.3 and 3.4 times higher than those of CNT-alpha-Fe(2)O(3 )and alpha-Fe2O3. nanocatalysts, respectively.
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    Fast one-pot laser-based fabrication of ZnO/TiO2-reduced graphene oxide nanocomposite for photocatalytic applications
    (Elsevier Ltd, 2023) Manda, Abdullah A.; Haladu, Shamsuddeen A.; Elsayed, Khaled; Gaya, Umar İbrahim; Alheshibri, M.; Al, Baroot, A.; Çevik, Emre
    Laser synthesis is rapidly emerging to be an efficient and unique method for the synthesis of a wide spectrum of nanomaterials owing to its ease of setup, simplicity, and generation of high-purity nanomaterials. This study explores a pulse laser ablation protocol in the synthesis of ZnO-TiO2 (ZT) and ZnO-TiO2-reduced graphene oxide (ZT-rGO) nanocomposites. The effect of rGO loading (5 %, 10 %, and 20 %) was investigated on the nature of the crystalline nanostructures formed, the increased thermal stability achieved, and the effective removal of methylene blue dye. Following fabrication, the nanocatalyst materials were characterized by TEM, PXRD, SEM/EDX, AFM, UV–Vis, TGA, and FTIR. Using UV illumination, the as-synthesized photocatalysts were evaluated in the photodegradation of methylene blue (MB) as a model dye pollutant. Among the nanocomposites, the ZT-rGO 5 % shows the best photocatalytic activity by having a preferential rate constant of 0.149 min?1. The nanocomposites were prepared in 30 min, providing 98.5 % MB removal within just 30 min, using 10 mg/L of MB and 20 mg/L of the catalyst. During the photodegradation process, the rGO component serves as an electron trap, thus enhancing the formation of holes which are the mainstay of any photocatalytic process. As demonstrated by the work reported, the laser ablation technique shows great promise in the fabrication of ZT-rGO nanocomposites and similar analogs relevant to the efficient decolorization of wastewater. © 2022 Elsevier Ltd
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    Synthesis of Ag nanoparticles-decorated on CNTs/TiO2 nanocomposite as efficient photocatalysts via nanosecond pulsed laser ablation
    (Elsevier Sci Ltd, 2022) Alheshibri, Muidh; Elsayed, Khaled; Haladu, Shamsuddeen A.; Magami, Saminu Musa; Al Baroot, Abbad; Ercan, İsmail; Ercan, Filiz
    A simple, reproducible, and non-surfactant self-templating approach was developed for the synthesis of silver nanoparticles decorated on CNTs/TiO2 nanocomposite via a nanosecond pulsed laser ablation method. In addition, the effective use of the resulting nanocatalysts was carried out in the enhanced photocatalytic degradation of methylene blue dye contaminant. Following the synthesis of the nanocomposite catalysts, their morphology, heterostructure, and the nature of incorporation of their constituents were confirmed by TEM and SEM microscopy. In addition, characteristic diffraction patterns of the materials were studied by XRD powder diffraction method, confirming the crystalline nature of the nanocatalysts. The photoluminescence (PL) analysis provided information about the surface defects present as well as the electron-hole recombination properties of the prepared nanocatalysts. Despite the poor ultraviolet light absorption of the neat CNT and the TiO2 constituents beyond 400 nm, an efficient ultraviolet light-induced photodegradation of the methylene blue dye was successfully achieved. In this, by carrying out 50 min of ultraviolet light irradiation of the dye in the presence of the TiO2/CNT and the Ag/TiO2/CNT nanocomposite catalysts, 89.8% and 96 % reduction efficiencies were achieved, respectively. The experimental error associated with the photodegradation efficiency was within +/- 3%. The ultraviolet light-induced catalytic degradation of the dye follows first-order reaction kinetics, with rate constants of 3.95 x10-2 min-1 and 4.56 x 10-2 min-1 associated with the TiO2/CNT and the Ag/TiO2/CN catalyzed reactions, respectively.