Browsing by Author "Caglar, A."
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Book Part Metal-Free Catalysts for Hydrogen Production(Elsevier, 2022) Caglar, A.; Hansu, T.A.; Demir-Kivrak, H.Catalysts are vital for speeding up the reaction during hydrogen production. Both metal-based and metal-free catalysts are used. Metal-free catalysts are less expensive than metal-based catalysts and do not have the disadvantages of oxidation and poisoning. Metal-free catalysts doped with heteroatoms, carbon materials, and polymers have been investigated for their high catalytic activity in hydrogen production. Carbon materials are typically high-surface-area carbon forms such as activated carbon, carbon nanotubes, fullerene, graphite, and graphene. In addition, heteroatoms are obtained by adding atoms to carbon materials, such as replacing carbon atoms with heteroatoms such as N, P, or B or bonding heteroatoms such as S, CI, Br, or O to the carbon surface. Hydrogen is produced from boron-based chemical hybrids, water, and other sources. Sodium borohydride (NaBH4), ammonium borane (NH3BH3), and hydrazine borane (N2H4BH3) are boron-based hybrid chemical sources. Examining the different production methods of these hydrogen sources is important for achieving cheaper and more efficient hydrogen production. Water splitting is examined in three categories: electrolysis, thermolysis, and photoelectrolysis. Furthermore, catalyst characterization is a technique that must be studied to relate catalytic activities with their properties. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric and differential thermal analysis techniques are examined to determine the composition and structure of metal-free catalyst surfaces. © 2022 Elsevier Inc. All rights reserved.Article 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.