Department of Chemical, Metallurgical and Materials Engineering -Research Articles

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    Statistical characterization and simulation of graphene-loaded polypyrrole composite electrical conductivity
    (Elsevier B.V., 2020-11-24) Folorunso, Oladipo; Hamam, Yskandar; Sadiku, Rotimi; Ray, Suprakas Sinha; Adekoya, Gbolahan Joseph
    In this study, an effective method has been described and adopted to quantify the diameter and length of graphene nanofiller. The experimentally measured graphene parameters were modelled by using the Weibull distribution. The fitted graphene nanofiller length and diameter were used to predict the electrical conductivity of the graphene-loaded polypyrrole. The reliability of the dispersion of the filler in the matrix is, aided by the adequate distribution of the filler. An analytical model was developed to study the conductivity of the polypyrrole-graphene (PPy-Gr) composite. In the model, the interfacial effect of the composite constituents was considered and the electrical conductivity of the composite was determined by the simple-sum method. The percolation threshold and the electrical conductivity dependencies of the composites were evaluated by concurrently varying the potential barrier, filler electrical conductivity and the interfacial thickness and the matrix conductivity. The current model produced results, which are in good agreement with experimental measurements of different polymer-composites. It is envisaged that the method employed in this study, can be extended to other polymer-filler mixture as a predictive, optimization and design tool, for polymer composites of any type.
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    Effect of borophene and graphene on the elastic modulus of PEDOT:PSS film—A finite element study
    (MDPI, 2022-02-23) Adekoya, Gbolahan Joseph; Adekoya, Oluwasegun Chijioke; Sadiku, Emmanuel Rotimi; Hamam, Yskandar; Ray, Suprakas Sinha
    A finite element method (FEM) was employed to investigate the interaction of borophene nanoplatelets (BNPs) and graphene nanoplatelets (GNPs) on the mechanical properties of Poly (3,4- ethylene dioxythiophene): poly (styrene sulfonate) PEDOT: PSS film. A 3D random distribution of the inclusion into the PEDOT: PSS matrix was constructed by developing a 145 145 145 representative volume element (RVE) with a 4% volume fraction of BNPs and GNPs. In comparison to the pristine PEDOT: PSS, the calculated effective elastic moduli of the BNP-PEDOT: PSS and GNP-PEDOT: PSS nanocomposites exhibited 9.6% and 10.2% improvement, respectively. The predicted FE results were validated by calculating the elastic moduli of the nanocomposites using a modified Halpine-Tsai (H-T) model. The reinforcing effect of the inclusion into the PEDOT: PSS film offers a promising electrode with improved mechanical stability. Consequently, this intriguing result makes the BNP/PEDOT: PSS nanocomposite highly promising for further investigation and application in cutting-edge devices such as touchscreen, thermoelectric, light-emitting diode, electrochemical, photodiode, sensor, solar cell, and electrostatic devices.
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    Density functional theory interaction study of a polyethylene glycol-based nanocomposite with cephalexin drug for the elimination of wound infection.
    (American Chemical Society, 2022-09-12) Adekoya, Gbolahan Joseph.; Adekoya, Oluwasegun Chijioke.; Sadiku, Rotimi Emmanuel.; Hamam, Yskandar.; Ray, Suprakas Sinha.
    In this paper, density functional theory (DFT) simulations are used to evaluate the possible use of a graphene oxide-based poly(ethylene glycol) (GO/PEG) nanocomposite as a drug delivery substrate for cephalexin (CEX), an antibiotic drug employed to treat wound infection. First, the stable configuration of the PEGylated system was generated with a binding energy of −25.67 kcal/mol at 1.62 Å through Monte Carlo simulation and DFT calculation for a favorable adsorption site. The most stable configuration shows that PEG interacts with GO through hydrogen bonding of the oxygen atom on the hydroxyl group of PEG with the hydrogen atom of the carboxylic group on GO. Similarly, for the interaction of the CEX drug with the GO/PEG nanocomposite excipient system, the adsorption energies are computed after determining the optimal and thermodynamically favorable configuration. The nitrogen atom from the amine group of the drug binds with a hydrogen atom from the carboxylic group of the GO/PEG nanocomposite at 1.75 Å, with an adsorption energy of −36.17 kcal/mol, in the most stable drug−excipient system. Drug release for tissue regeneration at the predicted target cell is more rapid in moist conditions than in the gas phase. The solubility of the suggested drug in the aqueous media around the open wound is shown by the magnitude of the predicted solvation energy. The findings from this study theoretically validate the potential use of a GO/ PEG nanocomposite for wound treatment application as a drug carrier for sustained release of the CEX drug.
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    Applications of mxene-containing polypyrrole nanocomposites in electrochemical energy storage and conversion.
    (American Chemical Society, 2022-10-25) Adekoya, Gbolahan Joseph.; Adekoya, Oluwasegun Chijioke.; Sadiku, Rotimi Emmanuel.; Hamam, Yskandar.; Ray, Suprakas Sinha.
    The atomically thick two-dimensional (2D) materials are at the forefront of revolutionary technologies for energy storage devices. Due to their fascinating physical and chemical features, these materials have gotten a lot of attention. They are particularly appealing for a wide range of applications, including electrochemical storage systems, due to their simplicity of property tuning. The MXene is a type of 2D material that is widely recognized for its exceptional electrochemical characteristics. The use of these materials in conjunction with conducting polymers, notably polypyrrole (PPy), has opened new possibilities for lightweight, flexible, and portable electrodes. Therefore, herein we report a comprehensive review of recent achievements in the production of MXene/PPy nanocomposites. The structural− property relationship of this class of nanocomposites was taken into consideration with an elaborate discussion of the various characterizations employed. As a result, this research gives a narrative explanation of how PPy interacts with distinct MXenes to produce desirable high-performance nanocomposites. The effects of MXene incorporation on the thermal, electrical, and electrochemical characteristics of the resultant nanocomposites were discussed. Finally, it is critically reviewed and presented as an advanced composite material in electrochemical storage devices, energy conversion, electrochemical sensors, and electromagnetic interference shielding.
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    Numerical investigation and response surface optimization of the effective modulus and electrical and thermal conductivities of the borophene nanoplatelet-reinforced PEDOT: PSS nanocomposite for energy storage application.
    (American Chemical Society, 2022-12-13) Adekoya, Gbolahan Joseph.; Adekoya, Oluwasegun Chijioke.; Sadiku, Rotimi Emmanuel.; Hamam, Yskandar.; Ray, Suprakas Sinha.
    Conductive organic nanocomposites have been widely employed to achieve a variety of purposes, particularly for energy storage applications, making it necessary to investigate transport properties such as electron and heat transport qualities based on geometric shapes and component materials. Due to the solid B−B bonds, unique atomic structure, and energy storage potential, borophene has received significant attention due to its reported ultrahigh mechanical modulus and metallic conduction. Herein, we investigated the effect and interaction of content materials (volume fraction) and geometric parameters such as the aspect ratio and orientation of borophene nanoplatelet (BNP) inclusions on the mechanical integrity and transport features (electrical and thermal conductivities) of a poly(3,4-ethylene dioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) electrode. The boundary condition is crucial in developing the predictive models for the optimized mechanical and transport properties of the composites. The effective modulus, electrical conductivity, and thermal conductivity of the BNP-reinforced PEDOT:PSS-based nanocomposite are evaluated using the periodic boundary condition, the representative volume element-based finite element homogenization, and statistical analysis response surface techniques. The optimal parameters for the PEDOT:PSS/BNP nanocomposite for energy storage application are predicted based on the desirability function to have a 13.96% volume fraction of BNPs, having an aspect ratio of 0.04 at 45° inclination. The desirability value achieved for the material hinges was 0.78 with a predicted Young’s modulus of 6.73 GPa, the electrical conductivity was 633.85 S/cm, and the thermal conductivity was 1.96 W/m K at a generally high predictive performance of <0.03 error. The effective thermal conductivity of the nanocomposite was determined by considering Kapitsa nanoeffects, which exhibit an interfacial thermal resistance of 2.42 × 10−9 m2 K/W. Based on these improved findings, the enhanced PEDOT:PSS/BNP nanocomposite electrode would be a promising material for metal-ion batteries.
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    Response surface optimization and finite element homogenization study of the effective elastic modulus and electrical conductivity of MXene-polypyrrole hybrid nanocomposite as electrode material for electronic energy storage devices.
    (Wiley, 2022-11-15) Ezika, Anthony Chidi.; Sadiku, Emmanuel Rotimi.; Adekoya, Gbolahan Joseph.; Hamam, Yskandar.; Ray, Suprakas Sinha.
    Electrical energy storage devices are crucial for energy storage and distribution purposes. MXene (MX), a 2D material, and conductive organic polymers, such as polypyrrole (PPy), have been widely used as electrode material in electronic energy storage devices. This work calculated the elastic modulus and the electrical conductivity of a MX/PPy nanocomposite electrode using a finite element model. Response Surface Methodology (RSM) was used to optimize the electrical conductivity and elastic modulus response variables based on the finite element (FE) simulation findings. By assigning appropriate weights to these response factors in the optimization technique, the impacts of mass fraction and aspect ratio (AR) of MX inclusion on the electrical conductivity values and elastic modulus of the electrode were analyzed. When compared to the experimental findings, the results demonstrated that the suggested finite element model could provide a satisfactory estimate of the electrical conductivity and elastic modulus of the electrodes made of MX and PPy. However, these response variables might be optimized by using the response surface approach. Therefore, when RSM was employed, both electrical conductivity and Youngs modulus could be adjusted to close to their respective maximum optimal values, with a predicted electrical conductivity of 474.33 S/m and an elastic modulus of 3.24 GPa, at 50% mass fraction of the MX and the AR of 0.2. Based on these results, if a MX/PPy nanocomposite electrode could be built to achieve this modulus and electrical conductivity, such electrode would be a viable material for metal-ion batteries.
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    MXene/PPy nanocomposite as an electrode material for high-capacity Na-ion batteries investigated from first principle calculation.
    (Elsevier B.V., 2023-03-06) Ezika, Anthony Chidi.; Sadiku, Emmanuel Rotimi.; Ray, Suprakas Sinha.; Adekoya, Gbolahan Joseph.
    Mxene/Polypyrrole (Mxene/PPy) nanocomposite films are gaining importance for designing electrodes for energy storage applications. In this work, density functional theory (DFT) simulation is used to investigate the energy storage properties of PPy-based nanocomposite. The adsorption sites, adsorption energies, and electronic structures of Na storage abilities of Ti2CO2 MXene/PPy nanocomposite are all thoroughly investigated. The findings show that Na ion in Ti2CO2 MXene/PPy nanocomposite has high adsorption energy of 0.44 eV and a narrow energy bandgap of 0.02. The adsorption distance of the Na atom on the nanocomposite is relatively high. And according to charge transfer analysis from the electron density difference study, physisorption is the dominating adsorption mechanism for the Na-ion in the substrate. The Na-ion adsorbs onto the nanocomposite at 2.95 Å from the surface of the Ti2CO2 MXene and at a distance of 2.60 Å from the PPy. The projected density of state (PDOS) reveals the ability of the electrode to transmit electrons during the electrochemical process. This suggests that the Ti2CO2 MXene/PPy nanocomposite might be a promising Na-ion electrode material for battery use. As such, based on the nanocomposite’s metallicity, chemical stability, and capacity to absorb sodium ions with low adsorption energy, which can result in effective Na release. It may be recommended for use as an anode.
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    Structure‑property relationship and emerging applications of nanoand micro‑sized fillers reinforced sialon composites: A review.
    (Springer, 2024-04-07) Ogunbiyi, Olugbenga.; Jamiru, Tamba.; Adekoya, Gbolahan Joseph.; Rominiyi, Azeez Lawan.
    Oxonitridoaluminosilicates (SiAlON) are renowned in advanced ceramics for their exceptional properties: high temperature stability, excellent oxidation resistance, and good wear resistance. Incorporating micro- and nano-sized fillers into SiAlON matrices enhances their properties, yielding SiAlON composite materials with superior mechanical, tribological, and thermal characteristics. This review examines fabrication techniques for producing SiAlON micro/nanocomposites and the structure-property relationships governing their performance across different phase compositions (β, α, X, and O-phases). A comprehensive literature review scrutinized fabrication techniques and structure-property relationships from various databases and scholarly articles. Although SiAlON composites with micro/nano inclusions hold promise across applications, understanding their fabrication processes, structure-property relationships, and potential applications in different fields is crucial. The review highlights diverse fabrication techniques for SiAlON micro/nanocomposites and provides insights into their structure-property relationships. Additionally, emerging applications in structural domains, cutting tools, coatings, corrosion protection, solar cells, LEDs, biomedical realms, and filtration membranes are discussed. This review is a valuable resource for researchers and engineers interested in designing SiAlON products tailored for sophisticated applications. It emphasizes understanding fabrication processes and structure-property relationships to unlock SiAlON-based materials' full potential across industries.
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    Integrated study of antiretroviral drug adsorption onto calcined layered double hydroxide clay: experimental and computational analysis.
    (Springer, 2024-04-22) Tabana, Lehlogonolo Shane.; Adekoya, Gbolahan Joseph.; Tichapondwa, Shepherd Masimba.
    This study focused on the efficacy of a calcined layered double hydroxide (CLDH) clay in adsorbing two antiretroviral drugs (ARVDs), namely efavirenz (EFV) and nevirapine (NVP), from wastewater. The clay was synthesized using the co-precipitation method, followed by subsequent calcination in a muffle furnace at 500 °C for 4 h. The neat and calcined clay samples were subjected to various characterization techniques to elucidate their physical and chemical properties. Response surface modelling (RSM) was used to evaluate the interactions between the solution’s initial pH, adsorbent loading, reaction temperature, and initial pollutant concentration. Additionally, the adsorption kinetics, thermodynamics, and reusability of the adsorbent were evaluated. The results demonstrated that NVP exhibited a faster adsorption rate than EFV, with both reaching equilibrium within 20–24 h. The pseudo-second order (PSO) model provided a good fit for the kinetics data. Thermodynamics analysis revealed that the adsorption process was spontaneous and exothermic, predominantly governed by physisorption interactions. The adsorption isotherms followed the Freundlich model, and the maximum adsorption capacities for EFV and NVP were established to be 2.73 mg/g and 2.93 mg/g, respectively. Evaluation of the adsorption mechanism through computational analysis demonstrated that both NVP and EFV formed stable complexes with CLDH, with NVP exhibiting a higher affinity. The associated adsorption energies were established to be −731.78 kcal/mol for NVP and −512.6 kcal/ mol for EFV. Visualized non-covalent interaction (NCI) graphs indicated that hydrogen bonding played a significant role in ARVDs-CLDH interactions, further emphasizing physisorption as the dominant adsorption mechanism.
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    Computational investigation of the interaction mechanisms of low-density polyethylene (LDPE)/polyurethane and low-density polyethylene (LDPE)/hexane systems as absorbents for oil spill remediation: A DFT study.
    (Wiley, 2023-12-27) Odera, Raphael Stone.; Ezika, Anthony Chidi.; Adekoya, Gbolahan Joseph.; Sadiku, Emmanuel Rotimi.; Okpechi, Victor Ugochukwu.; Oyeoka, Henry Chukwuka.
    The escalating frequency of oil spill incidents and industrial wastewater discharges necessitates the development of effective remediation strategies. Inthis study, we conduct a comprehensive computational investigation using density functional theory (DFT) to elucidate the interaction mechanisms within polyethylene (PE) combined with polyurethane (PU) and hexane. The study focuses on adsorption energies, intermolecular interactions, miscibility, and electronic properties, providing a molecular level understanding crucial for designing advanced absorbent materials. The investigation reveals that the low-density polyethylene/polyurethane (LDPE/PU) system exhibits significantly higher adsorption energies (12.87 kcal/mol) compared to PE/hexane (7.66 kcal/mol), indicating a robust binding affinity. This discrepancy underscores the superior performance of PE/PU as an absorbent material. The enthalpy results, with H values of 55.75 kcal/mol for PE/hexanen-hexadecane and 66.11 kcal/mol for PE/PU-n-hexadecane complexes at 298.15 K, support exothermic adsorption. The more exothermic Δ H for PE/PU indicates stronger interactions during oil absorption than PE/hexane. Additionally, Gibbs free energy change (ΔG) values affirm a more favorable process for PE/PU, exhibiting a lower ΔG (42.54 kcal/mol) compared to PE/hexane (34.79 kcal/mol). Non- covalent interaction (NCI) studies confirm the importance of van der Waals forces in both systems, validating their role in the adsorption process. Miscibility studies indicate limited interactions, with PE/PU showing positive enthalpy of mixing. Electronic study demonstrates PE/PU's higher energy gap of 9.19 eV, correlating with superior performance. This research contributes to the fundamental understanding of oil absorption processes and informs the design and optimization of environmentally sustainable and efficient oil-absorbing materials for remediation applications. Highlights DFT explores polymeric systems, PE/PU and PE/hexane, for oil absorbent. • PE/PU excels with 12.87 kcal/mol adsorption energy, surpassing PE/hexane (7.66 kcal/mol) • NCI validates van der Waals forces in both systems, crucial for effective adsorption. • Miscibility studies reveal limited interactions. • PE/PU's superior 9.19 eV energy gap signifies enhanced absorbent performance. • PE/PU excels as an oil-absorbent material, underlining its overall superiority.