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    A comprehensive study on the synthesis, characterization and mathematical modeling of nanostructured Co-based catalysts using different support materials for AB hydrolysis
    (Springer International Publishing Ag, 2021) Kazici, Hilal Celik; Izgi, Mehmet Sait; Sahin, Omer
    The present work includes the synthesis of aluminum oxide (Al2O3), multi-walled carbon nanotube (MWCNT), and Eupergit CM-supported Co-based nanoparticles (Co-Fe-B and Co-Mn-B), and the investigation of their hydrolytic efficiency in H-2 generation from the catalytic hydrolysis of ammonia borane (NH3BH3). Among the supported catalysts, Co-Fe-B/Eupergit CM exhibited the highest H-2 generation rate as 4539 mLmin(-1)g(catalyst)(-1) compared to Co-Fe-B/Al2O3 and Co-Fe-B/MWCNT, which exhibited 4373 mLmin(-1)g(catalyst)(-1) and 3294 mLmin(-1)g(catalyst)(-1), respectively. When Co-Mn-B/ Eupergit CM was used instead of Co-Fe-B/ Eupergit CM, a significant increase in the highest HGR (19.422 mLmin(-1)g(catalyst)(-1)) was found. Moreover, turnover frequency (TOF) value was calculated as 318 h(-1) and 646 h(-1) for Co-Fe-B/Eupergit CM and Co-Mn-B/Eupergit CM, respectively.
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    CeO2 supported multimetallic nano materials as an efficient catalyst for hydrogen generation from the hydrolysis of NaBH4
    (Pergamon-Elsevier Science Ltd, 2020) Izgi, Mehmet Sait; Baytar, Orhan; Sahin, Omer; Kazici, Hilal Celik
    Nowadays, there is still no suitable method to store large amounts of energy. Hydrogen can be stored physically in carbon nanotubes or chemically in the form of hydride. In this study, sodium borohydride (NaBH4) was used as the source of hydrogen. However, an inexpensive and useful catalyst (Co-Cr-B/CeO2) was synthesized using the NaBH4 reduction method and its property was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), x-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) measurements. The optimized Co-Cr-B/CeO2 catalyst exhibited an excellent hydrogen generation rate (9182 mLg(metal)(-1) min(-1)) and low activation energy (35.52 kJ mol(-1)). The strong catalytic performance of the Co-Cr-B/CeO2 catalyst is thought to be based on the synergistic effect between multimetallic nanoparticles and the effective charge transfer interactions between the metal and the support material. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Co-Mn-B Nanoparticles Supported on Epoxy-Based Polymer as Catalyst for Evolution of H2 from Ammonia Borane Semi-Methanolysis
    (Springer, 2022) Kazici, Hilal Celik; Izgi, Mehmet Sait; Sahin, Omer
    A high-density and low-cost hydrogen generation technology is required for hydrogen energy systems. Non-noble multimetallic Co-Mn-B nanoparticles can serve as a good catalyst because of their low cost and ability to produce hydrogen gas during the catalytic semi-methanolysis process. This work reports the synthesis, characterization, and the use of Co-Mn-B catalyst supported on Eupergit CM as a very active and reusable catalyst for the generation of hydrogen from the semi-methanolysis of ammonia borane (AB). Solid materials were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX), and scanning electron microscopy (SEM). Rates of hydrogen generation were used to determine the kinetics of semi-methanolysis reaction. The parameters examined, namely the percentage of NaOH, percentage of metal loading, amount of catalyst particles, and AB concentrations and temperatures, were 1-5 (wt)%, 5-10 (wt)%, 5-50 mg, 0.5-3 mmol, and 30-60 degrees C, respectively. Total turnover frequency (TOF) value, hydrogen generation rate, and activation energy (Ea) were obtained at 30 degrees C as 15,751 h(-1), 17,324 mL g(cat)(-1)min(-1) (3 mmol AB and 25 mg Co-Mn-B/Eupergit CM), and 43.936 kJ mol(-1), respectively.
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    Hydrogen production by using Ru nanoparticle decorated with Fe3O4@SiO2-NH2 core-shell microspheres
    (Pergamon-Elsevier Science Ltd, 2020) Izgi, Mehmet Sait; Ece, M. Sakir; Kazici, Hilal Celik; Sahin, Omer; Onat, Erhan
    Noble metals are commonly used in order to accelerate the NH3BH3 hydrolysis for H2 production as heterogeneous catalysts. The nanoparticles (NPs) of these metals can be applied as active catalysts in fluid reactions. Metal NPs included in the core-shell nano- structures emerged as well-defined heterogeneous catalysts. Additionally, unsupported NPs catalysts can be gathered easily among neighboring NPs and the separation/recovery of these catalysts are not efficient with traditional methods. For this reason, here, silica-shell configuration was designed which was functionalized with a magnetic core and amine groups and Ru NPs were accumulated on Fe3O4@SiO2-NH2 surface for H-2 production from NH3BH3. Fe3O4@SiO2-NH2-Ru catalysts demonstrated high catalytic activity as long as it has a hydrogen production rate of 156381.25 mLg(cat)(-1)min(-1) and a turnover frequency (TOF) of 617 mol(H2) mol(cat)(-1)min(-1) towards the hydrolysis dehydrogenation of AB at 30 degrees C. This result is significantly higher than most of the known catalysts. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Synthesis of Metal-Oxide-Supported Triple Nano Catalysts and Application to H2 Production and H2O2 Oxidation
    (Springer, 2020) Kazici, Hilal Celik; Salman, Firat; Izgi, Mehmet Sait; Sahin, Omer
    Magnesium oxide (MgO)-supported nanocatalysts are a highly insulating crystalline solid with a sodium chloride crystal structure and excellent properties including chemical inertness, high temperature stability and high thermal conductivity. Here, a ternary alloy catalyst of MgO-supported CoMoB was synthesized by means of a chemical reduction method using ethylene glycol solution. The prepared CoMoB/MgO catalysts were characterized using x-ray diffraction, scanning electron microscopy (SEM/EDX) and Fourier transform infrared spectroscopic analysis. The CoMoB/MgO nanocomposite served as the enabling platform for a range of applications including hydrogen production catalyst and hydrogen peroxide (H2O2) determination. It also showed a high hydrogen production rate (1000 mLgcat-1 min(-1)) and low activation energy (68.319 kJ mol(-1)) for the hydrolysis of ammonia borane. Additionally, the electro-oxidation performance of the CoMoB/MgO for H2O2 detection was studied by cyclic voltammetry and chronoamperometry. The CoMoB/MgO sensor demonstrated a wide linear range up to 10 mM with a detection limit of 3.3 mu M.