Browsing by Author "Egbeyale G B"

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    Effect of CEC of clay on thermal conductivity
    (Malaysian Journal of Science, 2016-12) Adegoke J A; Egbeyale G B
    The thermal conductivity of clay doped with different concentrations of nitrate of heavy metals is presented in this study. Clay sample from Omi Adio, Ibadan, Southwestern part of Nigeria was used to investigate this work. Cation exchange, which occurs naturally with soil water, was the method explored to carry out the investigation. A microprocessor-based thermal analyzer was used to determine the thermal conductivity while Atomic absorption spectrophotometer was used to determine the heavy metal concentration. 52.0 g clay sample was mixed with 70 cm3 of nitrate of Pb (II), Cd (II), Zn (II), Cr (II), Fe (II), Hg(II), Cu (II), and Ni (II) solutions at different concentrations; after which slabs of dimensions 4cm x 4cm x 1cm were made from the mixture of the clay sample with aqueous solutions of different concentrations and the thermal conductivities determined. Thermal conductivity values were plotted against concentration of nitrate of heavy metals; 400 ppm, 800 ppm, 1600 ppm, 3200 ppm and 6400 ppm. Results showed that thermal conductivity of clay increases with increase in the concentration of heavy metal adsorbed by the clay to an optimum level. The lowest thermal conductivity was found to be 0.06W/mK (for control clay) and the highest was found to be 0.38W/mK (at 6400ppm, Copper). For all the samples, thermal conductivity increases as the concentration of heavy metals increases to a certain optimum level above which cation exchange is no longer possible. From the results, it was concluded that the increase of concentration of heavy metals adsorbed by clay during cation exchange process contributes to its thermal conductivity
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    Fabrication and Characterization of Co and Li Doped TiO2 Photoanodes for High Efficiency Dye-Sensitized Solar Cells
    (2024-12) Oladosu, O A; Ogundeji T S; Adegboyega O; Ajani A S; Egbeyale G B; Lana G M; Awodele M K; Adedokun O
    The urgent need for a sustainable energy future has driven global efforts to transition from fossil fuels to renewable energy sources. However, challenges such as escalating energy demands, environmental degradation, and the accelerating climate crisis hinder this transition. Dye-sensitized solar cells (DSSCs) emerge as a promising alternative, offering potential advantages like affordability, flexibility, and enhanced efficiency. Titanium (IV) Oxide (TiO2), a widely studied semiconductor material, has been extensively explored for DSSC applications. However, its inherent limitations, including a wide bandgap, significant charge recombination losses, and low electrical conductivity, impede the development of efficient and cost-effective DSSCs. This study aims to address these challenges and contribute to the advancement of DSSC technology as a viable and sustainable energy solution. DSSCs were fabricated using TiO2 photoanodes doped with cobalt (Co) and lithium (Li) via a one-pot sol-gel synthesis approach. Ruthenium-based dye N719 was utilized as the sensitizer. Characterization techniques, including XRD, FTIR, DRS, FESEM, and EDX, were employed to analyze the structural, optical, morphological, and elemental properties of the synthesized materials. Doping with Co and Li effectively reduced the TiO2 bandgap from 3.18 eV to 3.12 eV and 2.88 eV, respectively, leading to enhanced short-circuit current density (Jsc) values of 10.97 mA/cm² and 12.37 mA/cm², respectively. Among the fabricated DSSCs, the Li-doped TiO2 photoanode demonstrated the highest power conversion efficiency of 5.3%, followed by Co-doped TiO2 (4.2%) and undoped TiO2 (3.3%). These findings highlight the potential of Li and Co-doped TiO2 as promising materials for the development of high-performance DSSCs.
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    Green synthesis and characterization of Graphene/SnO₂ nanocomposite photoanodes for enhanced DSSC performance
    (Nano Plus: Sci. Tech., 2025) Ojo A O; Adedokun K A; Gbadero D S; Oyetunji E O; Adegboyega O; Egbeyale G B; Ajani A S; Awodele M K; Adedokun O
    Dye-sensitized solar cells (DSSCs) offer a compelling alternative to conventional silicon-based solar cells due to their cost-effectiveness, flexibility, and relatively high efficiency. However, their performance is currently hindered by the photoanode material, typically titanium dioxide (TiO₂). This study aims to develop a green synthesis method for graphene/tin dioxide nanocomposites (G/ SnO₂ NCs) using Bryophyllum pinnatum extract for DSSC applications. SnO₂ nanoparticles (SnO2 NPs) were synthesized using a green method with Bryophyllum pinnatum extract and integrated with biomass-derived graphene to fabricate G/SnO₂ NCs for DSSC applications. Characterization techniques, including UV-Vis spectroscopy, XRD, FTIR, SEM, and EDX, were employed to analyze the optical, structural, functional, morphological, and elemental compositional properties of graphene, SnO₂, and the G/SnO₂ NCs. The photoanode thin films were deposited using the doctor blade technique, and their electrical properties were evaluated using four-point probe measurements. Results demonstrate that the G/SnO₂ NCs exhibit significantly enhanced electrical conductivity (0.148 S/m) compared to pristine SnO₂ (0.098 S/m) and graphene (0.122 S/m), indicating improved charge transport properties within the composite material. This enhancement is attributed to the synergistic effect of the high electron mobility of SnO₂ and the excellent conductivity of graphene. Furthermore, the G/SnO₂ NCs exhibit lower sheet resistance (549.48 Ω), further suggesting its potential for efficient charge collection in DSSC applications. The graphene/SnO₂ nanocomposites exhibited enhanced electrical conductivity, improved charge transport properties, and lower sheet resistance compared to pristine SnO₂ and graphene. These findings suggest that the synergistic combination of SnO₂ and graphene offers a promising pathway to improved efficiency in DSSC applications. This research contributes to the development of sustainable and cost-effective solar energy solutions, offering a promising alternative to conventional silicon-based solar cells.
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    Interpretation of airborne radiometric data of flamingo field, Southwestern Nigeria
    (Nigerian Society of Physical Sciences, 2025) Lawal T O; Fawale O; Sunday J A; Egbeyale G B
    The airborne radiometric data of the flamingo field, Southwest Nigeria has been analyzed and interpreted with the aim of evaluating the surface geology and structural features that are critical for mineral resource exploration. The objectives of the study are to delineate the alteration zones by correlating interpreted data with the lithological units, and to describe the relationship between the airborne radiometric anomalies and the subsurface structural trends. To achieve this, the data was subjected to rigorous qualitative and quantitative interpretation. Maximum and minimum concentration values for Total count (TC (Unit of radiation (Ur)) rate, Potassium (K), equivalent of Thorium (eTh) and that of Uranium (eU) were estimated. The results of the study show that the value of Ur, K, eTh %, and eU in flamingo field range from 2.408 to 41.017, 0.162 to 3.238 (%), 0.846 to 33.104 (ppm) and 0.169 to 7.232 (ppm), respectively. Locations of the associated anomalies which serve as alteration zones were obtained and values obtained from this expression clearly reveals that majority of the rock units for most of the radio elements in the area are below one hundred percent, while few others such as carbonaceous/slate phyllite, meta siltstone, undifferentiated schist and granite gneiss have values above 100%, especially for potassium and thorium elements. Also, the produced composite radioelements and image maps reveals bright some zones within the field which is a revelation of anomalous alteration zones. More so, the most prominent trend in the field correspond to the Northeast – Southwest and Northwest – Southeast directions which plays an important role in the structural framework of the study area.
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    Interpretation of airborne radiometric data of flamingo field, Southwestern Nigeria
    (NSPS, 2025) Lawal T O; Fawale O; Sunday J A; Egbeyale G B
    The airborne radiometric data of the flamingo field, Southwest Nigeria has been analyzed and interpreted with the aim of evaluating the surface geology and structural features that are critical for mineral resource exploration. The objectives of the study are to delineate the alteration zones by correlating interpreted data with the lithological units, and to describe the relationship between the airborne radiometric anomalies and the subsurface structural trends. To achieve this, the data was subjected to rigorous qualitative and quantitative interpretation. Maximum and minimum concentration values for Total count (TC (Unit of radiation (Ur)) rate, Potassium (K), equivalent of Thorium (eTh) and that of Uranium (eU) were estimated. The results of the study show that the value of Ur, K, eTh %, and eU in flamingo field range from 2.408 to 41.017, 0.162 to 3.238 (%), 0.846 to 33.104 (ppm) and 0.169 to 7.232 (ppm), respectively. Locations of the associated anomalies which serve as alteration zones were obtained and values obtained from this expression clearly reveals that majority of the rock units for most of the radio elements in the area are below one hundred percent, while few others such as carbonaceous/slate phyllite, meta siltstone, undifferentiated schist and granite gneiss have values above 100%, especially for potassium and thorium elements. Also, the produced composite radioelements and image maps reveals bright some zones within the field which is a revelation of anomalous alteration zones. More so, the most prominent trend in the field correspond to the Northeast – Southwest and Northwest – Southeast directions which plays an important role in the structural framework of the study area.