Browsing by Author "Adedokun O"

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    Plasmonic enhancement of visible light absorption in Ag-TiO2 based dye-sensitized solar cells
    (2021) Alamu GA; Adedokun O; Bello IT; Sanusi YK
    This work assessed the effect of plasmonic green synthesized silver nanoparticles (AgNPs) dispersed in Titanium dioxide (TiO2) nanoparticles on the efficiency of DSSC. Natural plant extracts from air-dried Neem (Azadirachta indica) and Henna (Lawsonia inermis) leaves were used as sensitizers with commercially available Ruthenium dye (N719). The optical absorption band obtained at 425 nm confirmed the presence of the AgNPs and incorporating the AgNPs into TiO2 and dye loading increased the absorbance significantly. The optical band gap results showed that the energy gap decreased as the absorbance increased. The DSSC sensitized by N719 dye offered the highest conversion efficiency of 4.09%, followed by 1.57% by Neem extract and 1.18% by Henna extract. It was shown from the results that natural plant extracts as sensitizers and plasmonic green synthesized AgNPs incorporated into TiO2 as the photoanode are good materials for the fabrication of DSSC with outstanding environmental friendliness.
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    Synthesis, characterization, and photocatalytic application of silver doped zinc oxide nanoparticles
    (2022) Kareem MA; Bello IT; Shittu HA; Sivaprakash P; Adedokun O; Arumugam S
    The advancement in nanotechnology has influenced the improvement in the photocatalytic performance of zinc oxide nanoparticles (ZnO NPs). The photocatalytic activities of ZnO are within irradiation wavelengths in the ultraviolet region and this hinders its efficiency in photocatalytic applications. Undoped and silver doped ZnO nanoparticles (Ag-doped ZnO NPs) were successfully prepared by co-precipitation technique at Ag doping concentrations of 0, 0.25, 0.5, 0.75, and 1 % to enhance the photocatalytic ability of ZnO NPs. The XRD results indicate a hexagonal wurtzite structure of the undoped and Ag-doped ZnO NPs with the estimated crystalline size ranges from 30.79, 23.72, 36.97, 21.49, and 25.66 nm, respectively, for ZnO at Ag doping concentrations. The SEM micrograph revealed the uniform distribution of Ag on the surface of ZnO NPs and a decrease in the size of the particle as concentration increases. The displacement in the absorption edge of ZnO to a higher wavelength led to narrowing the optical bandgap of ZnO due to Ag doping, as observed in the DRS spectra. Photocatalytic performance and photodegradation experiments were conducted using a model methylene blue (MB) dye contaminated in water. The dye concentration decreases as irradiation time increases in the presence of the photocatalyst with the improved performance of less exposure time and the highest dye degradation of about 98 %. It was revealed that the photocatalytic activity of ZnO toward MB degradation was effectively improved by Ag doping. Therefore, Ag doping of ZnO NPs had the synergetic effect of enhancing the photocatalytic activity of ZnO NPs.