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    Bi2S3 and NiBiS3 electrocatalysts for alkaline hydrogen evolution reactions
    (Pergamon-Elsevier Science Ltd, 2025) Aksaray, Goncagul; Mert, Mehmet Erman; Mert, Basak Dogru; Kardas, Gulfeza
    Developing efficient and available catalysts is important for advancing hydrogen evolution reaction (HER) in alkaline water electrolysis, a promising technology for sustainable hydrogen production. This study reports the synthesis and electrochemical performance of Bi2S3 and NiBiS3 catalysts for the HER in alkaline water electrolysis. The catalysts were prepared via a hydrothermal method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The electrochemical behavior was evaluated using cyclic voltammetry (CV), cathodic current-potential curves (Tafel polarization), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) in 1 M KOH. The graphite electrode modified with NiBiS3 exhibited high catalytic activity. The significant increase in current density and decrease in polarization resistance from 3000 S2 cm2 (bare graphite) to 18.55 S2 cm2 were detected. The G/NiBiS3 electrode outperformed both the bare graphite and G/Bi2S3 electrodes, with the current density reaching-2.3 x 10-3 A cm-2 at-0.26 V. Morphological analysis revealed that Bi2S3 forms flower-like structures, while NiBiS3 exhibits a cauliflower-like morphology, providing increased active surface areas important for catalytic activity. The Tafel slope analysis confirmed the Volmer step as the rate-determining step in the HER mechanism, with the adsorbed hydrogen subsequently forming molecular hydrogen. Stability testing through CA demonstrated consistent catalytic activity, with the current density maintained at-0.014 A cm-2 over 75000 s. These findings demonstrate the potential of NiBiS3 as a reliable and effective catalyst for alkaline electrolysis-based sustainable hydrogen production.
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    Öğe
    Catalytic insights into methanol electrooxidation on Ni foam modified with Bi 2 O 3-Acetylene black-rGO: Synthesis, characterization, and performance evaluation
    (Pergamon-Elsevier Science Ltd, 2024) Aksaray, Goncagul; Mert, Mehmet Erman; Mert, Basak Dogru; Karda, Gulfeza
    The aim of this study was to develop efficient anode materials for direct methanol fuel cell applications. The Ni foam was modified with Bi 2 O 3 - acetylene black-rGO to increase catalytic activity toward methanol oxidation. The Bi 2 O 3 was synthesized via a straightforward green technique. The characterization was achieved by using Fourier transform infrared spectroscopy and X -Ray diffraction analysis. The transmission electron microscope and field emission scanning electron microscope was utilized to evaluate the surface properties of catalysts, and energy-dispersive X-ray spectroscopy were employed to determine the chemical composition. Bi 2 O 3 particles with diameters ranging from 15 to 75 nm were crystal structures in the (111), (220), (311), and (342) crystal planes. The performance of methanol electrooxidation in an alkaline medium was investigated using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques. The surface coverage of the redox species was 2.04 x 10 -5 mol g -1 , and the diffusion coefficient ranged between 8.02 x 10 -12 and 1.25 x 10 -13 cm 2 s - 1 . According to the obtained results, the Bi 2 O 3 - acetylene black-rGO modification enhanced the electrocatalytic activity of Ni foam against methanol oxidation in an alkaline medium.
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    Öğe
    Sustainable energy solutions: 3D printed PLA-NiMo@Ag for green hydrogen production
    (Pergamon-Elsevier Science Ltd, 2025) Mert, Basak Dogru; Nazligul, Huseyin; Aksaray, Goncagul; Mert, Mehmet Erman; Seyedzavvar, Mirsadegh; Kardas, Gulfeza
    This study investigates integration of green-synthesized nanocatalysts with 3D-printable material and use the resulting structures as electrocatalysts (NiMo@Ag-PLA electrode) in a photovoltaic-supported alkaline electrolysis system. Honeycomb-structured cathodes were created by fused deposition modeling (FDM), green-synthesized NiMo@Ag nanoparticles embedded to improve electrochemical activity. The characterization and surface monitoring were performed using UV-VIS, FTIR, Zeta potential analysis, AFM, XRD, FE-SEM-EDX, TEM and contact angle measurements, that confirmed the formation of core-shell structure with uniform dispersion in PLA matrix. Electrochemical tests revealed that the hydrogen evolution reaction (HER) performance was enhanced by lowering the onset potential to-255 mV vs. Ag/AgCl, increasing the current density by nearly ninefold at-2.0 V vs. Ag/AgCl compared to PLA, and reducing the charge transfer resistance by approximately twenty-fivefold relative to PLA. These findings show the potentiality of combining green-synthesized nano-materials with 3D printing and solar energy to develop efficient systems for sustainable hydrogen production.