Medany, S. S., A. Nafady, R. A. Soomro, and M. A. Hefnawy,
Construction of chitosan-supported nickel cobaltite composite for efficient electrochemical capacitor and water-splitting applications,
, vol. 14, issue 1, pp. 2453, 2024.
AbstractThe construction of highly efficient electrode material is of considerable interest, particularly for high capacitance and water-splitting applications. Herein, we present the preparation of a NiCo2O4-Chitosan (NC@Chit) nanocomposite using a simple hydrothermal technique designed for applications in high capacitance and water-splitting. The structure/composition of the NC@Chit composite was characterized using different analytical methods, containing electron microscope (SEM and TEM), and powder X-ray diffraction (XRD). When configured as an anode material, the NC@Chit displayed a high capacitance of 234 and 345 F g−1 (@1Ag−1 for GC/NC and NC@Chit, respectively) in an alkaline electrolyte. The direct use of the catalyst in electrocatalytic water-splitting i.e., HER and OER achieved an overpotential of 240 mV and 310 mV at a current density of 10 mA cm−2, respectively. The obtained Tafel slopes for OER and HER were 62 and 71 mV dec−1, respectively whereas the stability and durability of the fabricated electrodes were assessed through prolonged chronoamperometry measurement at constant for 10 h. The electrochemical water splitting was studied for modified nickel cobaltite surface using an impedance tool, and the charge transfer resistances were utilized to estimate the electrode activity.
Medany, S. S., M. A. Hefnawy, and S. M. Kamal,
High-performance spinel NiMn2O4 supported carbon felt for effective electrochemical conversion of ethylene glycol and hydrogen evolution applications,
, vol. 14, issue 1, pp. 471, 2024.
AbstractOne of the most effective electrocatalysts for electrochemical oxidation reactions is NiMn2O4 spinel oxide. Here, a 3-D porous substrate with good conductivity called carbon felt (CF) is utilized. The composite of NiMn2O4-supported carbon felt was prepared using the facile hydrothermal method. The prepared electrode was characterized by various surface and bulk analyses like powder X-ray diffraction, X-ray photon spectroscopy (XPS), Scanning and transmitted electron microscopy, thermal analysis (DTA), energy dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET). The activity of NiMn2O4 toward the electrochemical conversion of ethylene glycol at a wide range of concentrations was investigated. The electrode showed a current density of 24 mA cm−2 at a potential of 0.5 V (vs. Ag/AgCl). Furthermore, the ability of the electrode toward hydrogen evaluation in an alkaline medium was performed. Thus, the electrode achieved a current density equal 10 mA cm−2 at an overpotential of 210 mV (vs. RHE), and the provided Tafel slope was 98 mV dec−1.
Alamro, F. S., S. S. Medany, N. S. Al-Kadhi, H. A. Ahmed, and M. A. Hefnawy,
"Modified NiFe2O4-Supported Graphene Oxide for Effective Urea Electrochemical Oxidation and Water Splitting Applications",
Molecules, vol. 29, issue 6, 2024.
AbstractThe production of green hydrogen using water electrolysis is widely regarded as one of the most promising technologies. On the other hand, the oxygen evolution reaction (OER) is thermodynamically unfavorable and needs significant overpotential to proceed at a sufficient rate. Here, we outline important structural and chemical factors that affect how well a representative nickel ferrite-modified graphene oxide electrocatalyst performs in efficient water splitting applications. The activities of the modified pristine and graphene oxide-supported nickel ferrite were thoroughly characterized in terms of their structural, morphological, and electrochemical properties. This research shows that the NiFe2O4@GO electrode has an impact on both the urea oxidation reaction (UOR) and water splitting applications. NiFe2O4@GO was observed to have a current density of 26.6 mA cm−2 in 1.0 M urea and 1.0 M KOH at a scan rate of 20 mV s−1. The Tafel slope provided for UOR was 39 mV dec−1, whereas the GC/NiFe2O4@GO electrode reached a current of 10 mA cm−2 at potentials of +1.5 and −0.21 V (vs. RHE) for the OER and hydrogen evolution reaction (HER), respectively. Furthermore, charge transfer resistances were estimated for OER and HER as 133 and 347 Ω cm2, respectively.
Hefnawy, M. A., R. Abdel-Gaber, N. Al-Hoshani, and S. S. Medany,
Nickel Flower/Conducting Polymer Composite for Effective Ethanol Electrooxidation in Alkaline Medium,
, vol. 15, issue 2, pp. 261 - 271, 2024.
AbstractThe growing interest in energy demand became an important issue for several sectors like industry and transportation. Recently, fuel cells generated a new solution for global energy deficiency. Therefore, we developed a new catalyst for fuel cell applications that included nickel oxide nanoflower with polyaniline to enhance the electrooxidation of ethanol. The structure of the modified electrode was characterized by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). At the same time, surface morphology and structural thermal stability were utilized by Scanning electron spectroscopy (SEM) and Thermal gravimetric analysis (TGA), respectively. Otherwise, ethanol electrooxidation was studied by several electrochemistry techniques like cyclic voltammetry (CVs) and chronoamperometry (CA). The activity of the electrocatalyst toward ethanol conversion reached 32 mA cm−2 at a potential of 0.46 V (vs. Ag/AgCl). The effect of changing the thickness of the conducting polymer was studied to find out the optimum catalysis condition. Several chemical kinetics were calculated, like diffusion coefficient (D), Tafel slope, and transfer coefficient. The long-term stability of the modified electrode for 240 min. Whereas the anodic current decreased by 15% after continuous oxidation of ethanol in an alkaline medium.
Gamal, H., A. M. Elshahawy, S. S. Medany, M. A. Hefnawy, and M. S. Shalaby,
Recent advances of vanadium oxides and their derivatives in supercapacitor applications: A comprehensive review,
, vol. 76, pp. 109788, 2024.
AbstractBecause of the complexity of various oxidation states of vanadium, vanadium oxides show a large variety of stable and metastable structures, which pose an inevitable challenge to synthesize vanadium oxides with high purity, well-controlled stoichiometry, to their different morphologies and meticulously designed nanostructures, a must for high electrochemical performance devices for Supercapacitors. Vanadium oxide-based materials have been extensively studied for their metal-insulator transition behavior, and their unique characteristics that making them a promising candidate for electrochemical performance, supercapacitors and energy storage capabilities. This review article will discuss the synthesis methods, structural characterization techniques, and applications of vanadium oxide-based materials. We will also highlight the recent advances in vanadium oxide and provide insights into these materials' prospects in the Supercapacitors field.
Zaher, H. T., M. A. Hefnawy, S. S. Medany, S. M. Kamel, and S. A. Fadlallah,
Synergetic effect of essential oils and calcium phosphate nanoparticles for enhancement the corrosion resistance of titanium dental implant,
, vol. 14, issue 1, pp. 1573, 2024.
AbstractCalcium phosphate (CaPO4) coating is one of various methods that is used to modify the topography and the chemistry of Ti dental implant surface to solve sever oral problems that result from diseases, accidents, or even caries due to its biocompatibility. In this work, anodized (Ti-bare) was coated by CaPO4 prepared from amorphous calcium phosphate nanoparticles (ACP-NPs) and confirmed the structure by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) techniques. Ti-bare was coated by prepared CaPO4 through the casting process, and the morphology of Ti/CaPO4 was characterized by scanning electron microscope (SEM) where the nano-flakes shape of CaPO4 and measured to be 60 ~ 80 nm was confirmed. The stability of Ti-bare and coated Ti/CaPO4 was studied in a simulated saliva solution using electrochemical impedance spectroscopy (EIS) and linear polarization techniques to deduce their corrosion resistance. Furthermore, three essential oils (EO), Cumin, Thyme, and Coriander, were used to stimulate their synergistic effect with the CaPO4 coat to enhance the corrosion resistance of Ti implant in an oral environment. The fitting EIS parameters based on Rs [RctC]W circuit proved that the charge transfer resistance (Rct) of Ti/CaPO4 increased by 264.4, 88.2, and 437.5% for Cumin, Thyme, and Coriander, respectively, at 2% concentration.
Medany, S. S., M. A. Hefnawy, S. A. Fadlallah, and R. M. El-Sherif,
Zinc oxide–chitosan matrix for efficient electrochemical sensing of acetaminophen,
, vol. 78, issue 5, pp. 3049 - 3061, 2024.
AbstractThe acetaminophen is an antipyretic and nonopioid analgesic that is prescribed for the management of fever and mild to moderate pain. The detection of acetaminophen by ZnO and ZnO@Chitosan-modified electrodes made of glassy carbon was compared. Acetaminophen was detected using surfaces of ZnO and ZnO@Chitosan over a 10–50 µM concentration range. The detection limits for ZnO and ZnO@Chitosan were anticipated to be 0.94 and 0.71 μmol L−1, respectively. In a wide range of acidic, neutral, and basic mediums with varying pH values, the impact of a change in solution pH on acetaminophen sensitivity was investigated. Electrokinetic studies were used to evaluate the acetaminophen detection efficiency. The charge transfer resistance (Rc) for various surfaces was measured using electrochemical impedance spectroscopy (EIS). Using DFT studies, the synergistic effect of chitosan on zinc oxide was also shown. The Forcite model was used to calculate the surface interactions between chitosan and zinc oxide. Acetaminophen adsorption on the chitosan surface was also studied using the B3LYP density functional method.