Abdulkadir Levent

The growing demand for sustainable and high-performance energy storage systems has stimulated the development of biomass-derived electrode materials for supercapacitors. In this study, activated carbon (Cm-AC) was synthesized from Crataegus monogyna seeds and combined with magnetic iron oxide (Fe₃O₄) nanoparticles to fabricate a hybrid Cm-AC@Fe₃O₄ electrode. The incorporation of iron oxide into the activated carbon matrix altered the charge-storage mechanism from predominantly electrical double-layer capacitance to a hybrid process with a significant faradaic (diffusion-controlled) contribution. Electrochemical measurements in 1 M Na₂SO₄ showed that the specific capacitance increased from 145.92 to 270.68 F g⁻¹ at a scan rate of 5 mV s⁻¹. Dunn kinetic analysis revealed that diffusion-controlled faradaic processes accounted for up to 87.82% of the total capacitance at low scan rates, consistent with a dominant contribution from reversible Fe²⁺/Fe³⁺ redox reactions. Galvanostatic charge–discharge analysis yielded a specific capacitance of 351.51 F g⁻¹ at 0.5 A g⁻¹, while electrochemical impedance spectroscopy demonstrated reduced internal and charge-transfer resistances after Fe₃O₄ incorporation. A symmetric Cm-AC@Fe₃O₄ supercapacitor retained 87.5% of its initial capacitance after 10,000 charge–discharge cycles and delivered a maximum energy density of 10.35 Wh kg⁻¹ at a power density of 396 W kg⁻¹. These findings demonstrate that biomass-derived Cm-AC@Fe₃O₄ is a promising and sustainable electrode material for high-performance supercapacitor applications.

A polydentate oxaloyl dihydrazone ligand (H ₂ L) was synthesized using 2‐hydroxy‐1‐naphthaldehyde and oxaloyl dihydrazide, and its transition metal complexes with Cu(II), Co(II), Ni(II) and Fe(II) were prepared. The structures of the ligand and complexes were characterized by FT‐IR, UV–vis, LC–MS/MS, TGA/DTA, and NMR spectroscopy (for the ligand), while their magnetic, conductivity, and geometric properties were also evaluated. The electrochemical behavior of the ligand and its complexes was investigated by cyclic voltammetry, revealing quasi‐reversible redox processes. DNA‐binding studies performed using voltammetric methods indicated significant interaction between the complexes and calf thymus DNA, with the Cu(II) complex exhibiting the highest intrinsic binding constant, suggesting strong affinity toward DNA. Furthermore, the catalytic performance of the complexes was evaluated in the H ₂ O ₂ ‐mediated oxidation of cyclohexene under reflux in acetonitrile. Among the studied catalysts, the Co(II) complex demonstrated superior activity, achieving 99.0% ± 1.5% conversion and 81.4% ± 1.0% selectivity toward oxidation products in 2 h. These findings highlight the potential of oxaloyl dihydrazone‐based binuclear metal complexes as efficient oxidation catalysts and promising DNA‐interacting agents.

This work reports the green synthesis of zinc/zinc oxide nanoparticles (Zn/ZnO NPs) using Artemisia lerchiana extract as a biogenic reducing and stabilizing agent and their application as electrode materials for electrochemical energy storage. The structural and physicochemical properties of the synthesized Zn/ZnO NPs were characterized using UV–Vis spectroscopy, TEM–SEM, atomic force microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis, supporting the formation of crystalline Zn/ZnO nanostructures containing ZnO and metallic Zn phases. The electrochemical performance of Zn/ZnO NPs‐based electrodes was evaluated by cyclic voltammetry, galvanostatic charge–discharge measurements, and electrochemical impedance spectroscopy in different electrolyte media. The Zn/ZnO NPs‐modified electrodes exhibited combined electrical double‐layer and surface‐controlled pseudocapacitive behavior, with the highest electrochemical performance achieved in neutral Na ₂ SO ₄ electrolyte. Galvanostatic measurements revealed a specific capacitance of 329.7 F g ^{− 1} at 0.06 A g ^{− 1} and good cycling stability with 86.7% capacitance retention after 5000 cycles. Electrochemical impedance spectroscopy revealed low equivalent series resistance, efficient ion diffusion, and favorable charge‐transfer kinetics in neutral electrolyte media. These findings demonstrate that plant‐mediated Zn/ZnO nanostructures can serve as efficient and sustainable electrode materials for next‐generation electrochemical energy‐storage devices.

This study reports the synthesis and comprehensive characterization of a new Schiff-base ligand (L), derived from the condensation of 2,5-thiophenedicarboxaldehyde and sulfamerazine. The structural identity of L was unequivocally confirmed through elemental analysis, FT-IR, ¹H/¹³C NMR spectroscopy, and LC-MS/MS measurements. The electrochemical behavior of L was investigated on a glassy carbon electrode in an anhydrous medium, revealing an irreversible, diffusion-controlled redox process best described by an electrochemical-chemical mechanism. The interaction between L and DNA was examined using voltammetric and spectrophotometric techniques. Differential pulse voltammetry demonstrated a pronounced decrease (44.4%) in the guanine oxidation signal upon interaction with L, indicating strong binding with an estimated binding constant of 1.04 × 10⁶ M^-1. Complementary UV-Vis studies showed a hypochromic effect accompanied by a hypsochromic shift in the ligand's absorption spectrum, consistent with an intercalative binding mode, yielding a Kb value of 1.44 × 10⁶ M^-1. Molecular docking simulations supported the experimental findings by revealing that L preferentially binds within the minor groove of DNA. The interaction is stabilized through a network of noncovalent forces, including conventional hydrogen bonds, van der Waals interactions, C-H···X contacts, and π-sulfur contributions, with a calculated binding energy of - 8.8 kcal mol^- 1. Overall, the combined electrochemical, spectroscopic, and theoretical results demonstrate that the synthesized Schiff-base ligand L exhibits high affinity toward DNA, positioning it as a promising candidate for further pharmacological evaluation.

Green-synthesized silver nanoparticles (AgNPs) from Artemisia lerchiana exhibit uniform morphology, high capacitance, stable cycling, and efficient ion diffusion, offering eco-friendly electrodes for high-performance supercapacitors.