Yazar "Kose, Ahmet" seçeneğine göre listele

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    A DFT study of hydrogen adsorption on Pt modified carbon nanocone structures: Effects of modification and inclination of angles
    (Pergamon-Elsevier Science Ltd, 2023) Kose, Ahmet; Fellah, M. Ferdi
    The adsorption of hydrogen molecule on Pt modified carbon nanocone (CNC) structures was investigated by density functional method. Pt atom was modified by both doping and decorating on the structures with 180 & DEG;, 240 & DEG; and 300 & DEG; inclination angles of the CNC. The interactions of the hydrogen molecule on the ring and top sites of these modified structures were explored. Effect of doping and decorating of Pt atom on CNC structures has been also investigated. The adsorption enthalpy and Gibbs free energy values of the structure formed by doping the Pt atom at the ring are-118.4 and-85.3 kJ/mol, respectively. With the increase of the angle of inclination, the hydrogen interaction decreased at the ring and increased at the top. According to the results of this study, it is predicted that CNCs modified with Pt atom can be a promising hydrogen storage material under ambient conditions.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Biosensor for the early diagnosis of lung cancer: A DFT study on the applicability of metal-doped graphene structures
    (Elsevier Science Sa, 2024) Korucu, Seyma; Kose, Ahmet; Fellah, M. Ferdi
    The usability of metal-doped graphene structures as biosensor was investigated to develop a preliminary diagnosis of lung cancer in this study. The adsorption and sensing properties of graphene structures formed by doping metal atoms (Pt, Pd, Ni, Ir and Cu) toward aniline, toluene, styrene and benzene gases were examined. Using the DFT/WB97XD method with 6-31 G (d, p)/LANL2DZ basis sets, significant charge transfer from the target gases to the metal-doped graphene structures were observed. After adsorption, the HOMO-LUMO gap values of graphene structures doped with Pt, Cu, and Ni atoms have decreased. All adsorption processes are spontaneous according to the adsorption Gibbs free energy. The findings indicate that copper-doped and platinum-doped graphene have strong potential as electronic and work function sensors for detecting aniline, toluene, styrene, and benzene, which are biomarkers for lung cancer.
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    Computational insights from GCMC, MD and DFT simulations of propane separation in Mg-based MOFs: Binary selectivity toward methane, ethane, and nitrogen
    (Elsevier, 2026) Tunali, Omer Faruk; Kose, Ahmet; Yuksel, Numan; Ozbek, M. Olus; Fellah, M. Ferdi
    The separation of light hydrocarbons represents a critical challenge in both industrial and environmental contexts. The binary separation of propane from ethane, methane, and nitrogen was investigated, and selected MOF structures containing Mg atoms were evaluated using GCMC and MD simulations. For Mg-MOF-74, propane uptake was found to be in the range of 297.5-378.7 mg/g at pressures 0.1, 1 and 10 bar. Adsorption properties were specifically examined at 1 bar and 298 K, and isotherm fitting (Langmuir/Freundlich) confirmed the strong affinity of propane toward the MOF surface. Key transport and separation parameters, including diffusion selectivity, permeability, and membrane selectivity, were calculated, showing that propane exhibited significantly higher selectivity compared to other gases. DFT calculations revealed adsorption energies of -6.1 kJ. mol- 1 (without dispersion correction) and - 41.4 kJ.mol- 1 (including dispersion effects) for propane binding to the MOF framework. These findings highlight the promise of Mg-based MOFs for the selective adsorption of propane.
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    Formaldehyde Adsorption and Sensing: A Density Functional Theory Study on Pd4 Nanocluster Decorated CNT Structure
    (Budapest Univ Technology Economics, 2023) Yuksel, Numan; Kose, Ahmet; Fellah, Mehmet Ferdi
    The sensing of formaldehyde, one of the volatile organic compounds used in chemical processes, is very important. In this study, the adsorption and sensing of formaldehyde molecule on Pd-4 nanocluster decorated carbon nanotube (Pd-4-CNT) was investigated by using DFT method. The WB97XD hybrid method was used in DFT calculations. The adsorption energy value was calculated as -8.1 kJ/mol. This low adsorption energy confirms the very short recovery time and the predominance of weak interactions. There was a decrease of approximately 20% in the HOMO-LUMO gap after the interaction. This result shows that the Pd-4-CNT can be used as a sensor at room temperature.
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    Hydrogen adsorption, desorption, sensor and storage properties of Cu doped / decorated boron nitride nanocone materials: A density functional theory and molecular dynamic study
    (Pergamon-Elsevier Science Ltd, 2024) Kose, Ahmet; Fellah, M. Ferdi
    The hydrogen storage and sensor properties of Cu-modified boron nitride nanocone (BNNC) structure were comprehensively investigated using the density functional theory method (DFT). By replacing nitrogen atoms with copper atoms on the BNNC structure, the hydrogen molecule's adsorption enthalpy and Gibbs free energy values were calculated as -48.6 and -16.9 kJ/mol, respectively. 4 Cu-doped BNNC structure achieved a notable hydrogen storage capacity of 5.38 wt%. The molecular dynamics calculations demonstrate that the structure modified with four Cu atoms maintains its dynamic stability. Furthermore, this study reveals that the desorption temperatures tend to rise with an increase in the number of adsorbed hydrogen molecules, and the average desorption temperature under 1 atm pressure is determined to be 332 K. The changes of work function values after hydrogen adsorption point out that the Cu-modified BNNC has Phi-sensor feature. Overall, Cu-modified BNNC structures show promising potential as hydrogen storage materials in ambient conditions.
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    Hydrogen molecule adsorption and sensing on lanthanide (La) doped/decorated carbon nanotube and graphene structures
    (A V S Amer Inst Physics, 2023) Yuksel, Numan; Kose, Ahmet; Duzenli, Derya; Fellah, M. Ferdi
    The use of carbon nanotube (CNT) and graphene structures as doped and decorated with La atom as an adsorbent and a sensor material for hydrogen molecules was investigated by the density functional theory method. It is seen that the hydrogen interaction increased significantly after the La modification on the CNT and graphene. The fact that the adsorption enthalpy values are smaller than the liquefaction enthalpy value of hydrogen indicates that they can be used as adsorbent materials for hydrogen adsorption. While the adsorption energy values are better in the modification with La doping in the CNT structure, the results in the graphene structure are better in the decoration with the La atom. Charge transfer has occurred between the structures modified with La and the hydrogen molecule. After the hydrogen interaction, HOMO-LUMO gap values decreased in La-modified CNT structures and increased in graphene structures. This signifies that the La-modified CNT structures could be electronic sensors for hydrogen molecules. Consequently, the CNT and graphene structures doped and decorated with La can be used as adsorbents for hydrogen molecules. In addition, La-modified structures have electronic sensor properties.
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    Pt, Pd and Au decorated reduced graphene oxide: Sensing properties for phenol gas detection at room temperature
    (Elsevier Science Sa, 2024) Korucu, Seyma; Kose, Ahmet; Fellah, M. Ferdi
    The adsorbent and sensor properties of metal decorated (Pt, Au and Pd) reduced graphene oxide (rGO) structures for phenol gas were investigated using Density Functional Theory (DFT) method with WB97XD formalism. The NBO charge values suggest the occurrence of charge transfer from the phenol molecule to the rGO structures. After the adsorption of phenol, the HOMO-LUMO gap values of the Pt-decorated rGO structure were observed to decrease, while the work function values of the Pt-decorated rGO structure were found to increase. The recovery time for phenol molecule on the Pt-rGO structure was determined to be 0.0019 seconds. These results imply that the Pt-decorated rGO structure can function as a work function sensor in addition to an electronic sensor for phenol gas molecule.
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    Sensing properties of propylene oxide on Pt and Pd doped graphene sheets: A DFT Investigation
    (Elsevier Science Sa, 2022) Yuksel, Numan; Kose, Ahmet; Fellah, M. Ferdi
    The adsorption and detection of propylene oxide (PO), which is a volatile organic compound produced on a large scale industrially and used in polymerization reactions, is an important issue. In this study, the adsorption of propylene oxide on the metal-doped graphene sheets were investigated by periodical Density Functional Theory calculations. The HSEH1PBE (HSE06) hybrid method was used for theoretical calculations. It has been deter-mined that Pt-doped and Pd-doped graphene structures give adsorption energy values of -78.6 and -75.4 kJ/ mol, respectively. The sensors have been evaluated in terms of work function (phi) showing that each can be described as an phi-type gas sensor. In addition, it has been revealed that periodical theoretical calculations utilized in this study give more accurate results than calculations made with the GGA-PBE method. As a result, it has been determined that Pt-doped and Pd-doped graphene sheets are effective for PO adsorption, Pt-doped graphene layer can be used as an electronic sensor for PO, whereas Pd-graphene layer cannot be used.