Browsing by Author "Kivrak, H."

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Quantum Size Effect of Cadmium-Doped Titanium Dioxide Photocatalysts Towards Methylene Blue Degradation and Electrooxidation
(Springer, 2022) Kivrak, H.; Saleh, D., I; Alpaslan, D.; Caglar, A.; Selcuk, K.; Dudu, T. E.; Aktas, N.
At present, titanium dioxide supported cadmium catalysts were prepared at 0.5-5% cadmium loading by impregnation method. 0.5% Cd/TiO2 catalyst was characterized with scanning electron microscopy-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Characterization results revealed that by cadmium doping to titanium dioxide, surface electronic properties and crystal structure of Cd/TiO2 catalysts changed as obtained from SEM-EDX, XRD, and XPS. Following this, methylene blue degradation and electrochemical oxidation measurements were examined under UV light. Electrooxidation measurements were investigated to determine the methylene blue electrooxidation activities of titanium dioxide supported cadmium catalysts prepared at 0.5-5% cadmium loading with the cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy in 1 M KOH + 0.1875 M Methylene blue solution at 100 mV s(-1) in the dark and under UV light. Methylene blue oxidation measurements revealed that 0.5% Cd/TiO2 had the highest catalytic activity and stability in the dark and under UV illumination. 0.5% Cd/TiO2 electrode exhibited enhanced electrocatalytic activity under UV illumination. Photocatalytic methylene blue oxidation enhanced for 0.5% Cd/TiO2 by altering the surface electronic structure and crystal properties of titanium dioxide, assigned to structure sensitivity. As a result, this electrode production method is promising for the photocatalytic water remediation.
Structural and Photon/Neutron Attenuation Features of Pbni/Cnt Nanocomposites: an Experimental Approach
(Pergamon-elsevier Science Ltd, 2023) Yorgun, N. Yildiz; Kavaz, E.; Ulas, B.; Yilmaz, Y.; Kivrak, H.
In this work, PbNi/CNT nanocomposites were prepared by sodium borohydride method at varying metallic molar ratios for determination of their structural and nuclear radiation shielding properties. As-prepared PbNi/CNTs were characterized by using transmission electron microscopy (TEM), scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX), elemental mapping, and X-ray diffraction (XRD). Average particle sizes of Pb40Ni60/CNT, Pb60Ni40/CNT, Pb80Ni20/CNT, and Pb20Ni80/CNT materials were obtained as 5.6, 3.8, 4.2, and 4.2 nm, respectively. Radiation attenuation properties of the produced nanocomposites were investi-gated experimentally by irradiating the samples with gamma photons in the 34-383 keV energy range. The accuracy of the experimental results was checked with outcomes calculated with EpiXS software. Mass attenu-ation coefficient (MAC) was found in the range of 22.924-0.108 cm2/g, 5.473-0.129 cm2/g, 3.767-0.109 cm2/g, and 4.626-0.128 cm2/g for Pb20Ni80/CNT, Pb80Ni20/CNT, Pb40Ni60/CNT, and Pb60Ni40/CNT samples, respec-tively. Also, other photon shielding parameters (HVL, Zeff, EABF, and EBF) were calculated to make a comprehensive evaluation. The results show that 30% by weight Pb80Ni20 doped CNT has the lowest HVL and buildup factors values and the largest MAC, Zeff values. Finally, macroscopic cross-section values (sigma R) were obtained to estimate the ability of the nanocomposite samples to reduce the energy of fast neutrons. It was revealed that the sigma R values of the samples were in the range of 0.158-0.169 cm-1 and they had higher sigma R values than conventional neutron moderators.
Synthesis of Thiophenyl-Substituted Unsymmetrical Anthracene Derivatives and Investigation of Their Electrochemical and Electrooptical Properties
(Elsevier B.V., 2017) Kivrak, A.; Çalış, H.; Topal, Y.; Kivrak, H.; Kuş, M.
Novel thiophenyl-substituted anthracene derivatives (D-A) bearing a variety of electron-withdrawing groups were designed and synthesized for organic solar cells (OSCs). Their electrochemical and electro-optical properties were examined with strong donor-acceptor interaction. The electrochemical properties were examined by cyclic voltammetry (CV) measurements. These estimated values from CV measurements are in good agreement with the optical band gaps. HOMO, LUMO, and Eg values of designed organic materials were estimated. Furthermore, these new generation organic materials were fabricated to find their solar cell performances. © 2016 Elsevier B.V.