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Aktif karbon destekli ucuz ve kullanışlı katalizörün amonyak bor hidrolizinde incelenmesi
(2023) Beştaş, Hatice; Onat, Erhan; Şahin, Ömer; Demirci, Sevilay; Baytar, Orhan; İzgi, Mehmet Sait
Bu çalışmada ilk kez kahve çekirdeği atığından (kahve telvesinden) elde edilen aktif karbon kullanılarak CuMoB@AC ilk kez katalizörü sentezlendi. Burada en iyi katalitik performanslarını belirlemek amacıyla; Cu:Mo oranı, Metal/AC oranı, optimum NaOH oranı, katalizör miktarı, en uygun NH 3 BH 3 oranı ve farklı sıcaklıklarda yapılan deneyler sonucunda da reaksiyon kinetiği çıkarılarak reaksiyonun derecesinin n. dereceden (0.9) olduğu ve aktivasyon enerjisinin de 34,89 kJ/mol olduğu belirlendi. Aynı zamanda katalizörümüz karakterizasyonu belirlemek için SEM-EDS, XRD ileri analitiksel yöntemler kullanılarak belirlenmiştir.
An efficient synergistic Co@CQDs catalyst for hydrogen production from the hydrolysis of NH3BH3
(Springer, 2021) Onat, Erhan; Sahin, Omer; Izgi, Mehmet Sait; Horoz, Sabit
We report the synthesis of carbon quantum dots supported-Co (Co@CQDs) catalyst and its catalytic activity. The synthesized Co@CQDs catalyst for the first time is used to obtain the maximum hydrogen production rate from hydrolysis of NH3BH3. The synthesized Co@CQDs catalyst indicates a compelling performance in the hydrogen production from the hydrolysis of NH3BH3. It is found that Co@CQDs with the loading of Co (10 wt%) indicates a hydrogen production rate of 18600.27 mL/min.g(cat) and low activation energy of 22.97 kJ mol(- 1). The current study demonstrates that CQDs are promising support for dispersing metal catalysts. Moreover, the synthesized Co@CQDs catalyst is characterized by X-ray diffraction, ultraviolet and visible light, photoluminescence, inductively coupled plasma optical emission spectrometry, and transmission electron microscope measurements.
Computational study on a cobalt-based complex compound with amine ligand in X-doped (X = Co, Ru, Rh) Ca12Al14O33 functional material as an innovative catalyst by NaBH4 hydrolysis for determining hydrogen generation process
(Pergamon-Elsevier Science Ltd, 2024) Celik, Fatih Ahmet; Karabulut, Ezman; Izgi, Mehmet Sait; Yilmaz, Mucahit; Onat, Erhan
Sodium borohydride (NaBH4) has been generally studied as a source of hydrogen (H2) due to its important advantages with the development of support materials and catalysts for H2 release in the energy sector. In this context, we carry out molecular dynamics (MD) simulations by using extended tight-binding (xTB) model Hamiltonian based on density functional theory (DFT) and analyze the Ca12Al14O33 functional material doped X metals (X = Co, Ru, Rh) as a catalyst with [Co(III)(N3)3(C9H8N2)2] as complex compound with amine ligand from NaBH4 hydrolysis for H2 production. The use of a functional material doped by X metals causes to the high rate in H2 production when compared to without functional material doped by X metals. The increase of complex compound with amine ligand facilitates H2 production. Rh on the functional material displays the best catalytic performance compared to Ru and Co to increase the H2 production rate. Also, the increment of temperature has a positive effect on the H2 production rate with functional material doped Co, Ru and Rh metals. Thus, Ca12Al14O33 support material doped with noble metals appears promising as an innovative catalyst for H2 production.
Effect of Co-B Catalyst Synthesized in Methanol on the Hydrolysis of Sodium Borohydride
(2017) İzgi, Mehmet Sait; Şahin, Ömer; Onat, Erhan; Horoz, Sabit
Bu çalışmada, metanol içinde sentezlenen Co-B katalizörünün etkinliğini arttırmak için alternatif bir yöntem olarak soğuk bir plazma yöntemi seçilmiştir. İşlem süresi, sıcaklık, katalizör miktarı ve NaBH4 konsantrasyonları gibi parametrelerin Co-B katalizörün katalitik aktivitesi üzerindeki etkisi araştırılmış ve optimum koşullar belirlenmiştir. Maksimum hidrojen üretim oranı, metanolde sentezlenen Co-B katalizörü için 2200 mLH2/min.g. katalizör olarak bulunurken, suda sentezlenen Co-B katalizörü için 600 mLH2/min.g. katalizör olarak bulunmuştur. Metanolde hazırlanan Co-B katalizörü için aktivasyon enerjisi 34.694 kJ/mol olarak belirlenmiştir. Sonuç olarak, sonuçlarımız, farklı koşullardaki soğuk plazma işleminin, metanolde hazırlanan Co-B katalizörünün katalitik aktivitesini arttırmak için umut verici bir teknik olarak kullanılabileceğini göstermektedir
Epoxy-activated acrylic particulate polymer-supported Co-Fe-Ru-B catalyst to produce H2 from hydrolysis of NH3BH3
(Pergamon-Elsevier Science Ltd, 2020) Izgi, Mehmet Sait; Sahin, Omer; Onat, Erhan; Saka, Cafer
Epoxy-activated acrylic particulate polymer, namely Eupergit CM, supported Co-Fe-Ru-B catalyst (EP/Co-Fe-Ru-B) for the first time was used to produce H-2 from hydrolysis of NH3BH3. The EP/Co-Fe-Ru-B showed very effective performance in the production of H-2 from the hydrolysis of NH3BH3. Various techniques such as XRD, SEM-EDS, ICP-OES, and TEM have been used to characterize these catalysts. The parameters on the hydrolysis reaction of NH3BH3 such as the effect of metal amount, the effect of Ru percentage, the effect of NH3BH3 concentration, the effect of NaOH concentration, the amount of catalyst, temperature, and catalyst durability were investigated in detail. Eupergit CM based poly-mer support and Ru particles have been found to be highly effective in H-2 production re-actions. The hydrogen production rate (HGR) of the EP/Co-Fe-Ru-B catalyst was found to be 36,978 mL/min/g(cat), which was quite good compared to the values reported in the literature. In addition, the activation energy (Ea) of the polymer-supported Co-Fe-Ru-B catalyst was determined as 24.91 kJ/mol. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Green and active hydrogen production from hydrolysis of ammonia borane by using caffeine carbon quantum dot-supported ruthenium catalyst in methanol solvent by hydrothermal treatment
(Pergamon-Elsevier Science Ltd, 2024) Izgi, Mehmet Sait; Onat, Erhan; Sahin, Omer; Saka, Cafer
Here, carbon quantum dot (CQD) supported Ru nanoparticles from the caffeine in methanol or water by the hydrothermal method were synthesized for the first time to produce hydrogen (H-2) by hydrolysis of ammonia borane(NH3BH3) and their catalytic activities were investigated. The chemical compositions and morphology structures of this caffeine carbon dot-supported Ru catalysts were carefully characterized by UV, PL, TEM, FTIR, and ICP/OES analyses. Well-dispersed Ru nanoclusters with similar to 1.81 nm particle size on CQD by the hydrothermal method in methanol medium showed very good catalytic performance. The turnover frequency (TOF) obtained for H-2 production from the catalytic hydrolysis of 5% NH3BH3 with CQD supported Ru catalyst obtained by the hydrothermal method in methanol and water was found to be 361 and 1895 mol H-2 min(-1) mol(-1), respectively. The activation energies (Ea) for NH3BH3 hydrolysis with the same catalysts were measured as 33.32 and 27.80 kJmol(-1), respectively.
H2 2 production from ammonia borane hydrolysis with catalyst effect of Titriplex® ® III carbon quantum dots supported by ruthenium under different reactant Conditions: Experimental study and predictions with molecular modelling
(Elsevier Science Sa, 2024) Onat, Erhan; Celik, Fatih Ahmet; Sahin, Omer; Karabulut, Ezman; Izgi, Mehmet Sait
This study presents experimental and theoretical results on the role of the catalytic effect by ruthenium added titriplex (R) (R) III Carbon Quantum Dots (CQD) support material in the hydrolysis of ammonia borane for H2 2 duction. H2 2 production was achieved under different reactant conditions (in variable amounts of catalysis, ruthenium, NaOH, ammonia borane and at various temperature). Since the experimental results and theoretical calculations which includes the effect of all electrical forces acting on valence electrons (overlap density tions, van der Waals forces, Covalent bonding and halogen bonds) are in very good agreement in the study, theoretical predictions are also made. By considering the rhodium element instead of the ruthenium element, performance of the titriplex support material was estimated to be approximately 30% more effective ruthenium. The NaOH molecule acts as a hydrolyzed water molecule with catalysis interaction and contributes the formation of oxidized boron. When NaOH is not present, the interaction time of the ammonia borane molecule with catalysis comes to the fore. This time is called threshold time. In molecular modeling, while almost all of the ammonia borane molecules contribute to H production, only 15% of the water molecules contribute this rate. However, while some of the released H atoms remains in the water, other parts observe to play a role the production of H2 2 and hydronium. The interaction rate of the water molecule increases with the increase the interaction surface of the catalyst. Any external effect that prevents the formation of hydronium and celerates the interaction of free H atoms with each other increases the efficiency. One of the predicted results this study is that the increased pressure shows separating role for hydronium.
High availability and outstanding catalytic activity in sodium borohydride hydrolytic dehydrogenation of CQD/GO@Co catalyst by green synthesis: Experimental and computational perspective
(Pergamon-Elsevier Science Ltd, 2024) Onat, Erhan; Celik, Fatih Ahmet; Karabulut, Ezman; Izgi, Mehmet Sait
This study is a pioneering study that experimentally and theoretically measures the effect of heterogeneous catalyst structure on hydrogen production. In this research, the catalytic activity of the (CQD/GO@Co) catalyst, which was formed by doping Co onto the synthesized graphene oxide (GO) on carbon quantum dots (CQD) obtained from caffeine by green synthesis, was investigated. The catalyst CQD/GO@Co was synthesized with high dispersibility and activity, and it was successfully employed in the hydrolysis of NaBH4 for the first time. The effective catalytic compatibility of caffeine and cobalt element increased approximately 3 times on the GO layer. In order to determine the most effective catalyst conditions in the study, NaOH concentration, catalyst amount, NaBH4 amount and temperature were tested under different reactant conditions. The catalyst was characterized using X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) analyses. Field emission scanning electron micrographs (FESEM) were taken by Field emission scanning electron microscope (Zeiss, Sigma). Energy dispersive X-ray (EDX) spectra were obtained from Energy dispersive X-ray spectroscope. According to spherical aberration transmission electron microscopy studies, the uniform dispersion of Co nanoparticles (average diameter: +/- 3,1 nm) on CQDs, as well as the very small size and good dispersion of Cobalt (Co), are conducive to improved catalytic performance. This situation was determined by molecular modeling with the Non-scc GFN1xTB model and results supporting the experimental data were obtained. The maximum hydrogen production rate with sodium borohydride hydrolysis using cobalt-based catalyst increased approximately 32 times (from metallic crystal form of Co catalyst 2860 mL/min.(g.cat) to the present form 49,044 mL/min.(g.cat). The activation energy, activation enthalpy, and activation entropy of the Co@CQDs catalyst were founded to be 20.65 kJ mol(-1), 2.64 kJ mol(-1), and -108,97 J mol(-1), respectively.
Highly active hydrogen production from hydrolysis of potassium borohydride by caffeine carbon quantum dot-supported cobalt catalyst in ethanol solvent by hydrothermal treatment
(Pergamon-Elsevier Science Ltd, 2024) Onat, Erhan; Izgi, Mehmet Sait; Sahin, Omer; Saka, Cafer
Herein, the efficiency of the Co catalyst synthesized in caffeine-based carbon quantum dot- supported material using ethanol solvent was evaluated for H2 production from the hy- drolysis of KBH4. The chemical compositions and morphology structures of these caffeine carbon dot-supported Co catalysts were carefully characterized by XRD, TEM, BET, EDS, FTIR, XPS, and ICP/OES analyses. XPS, FTIR and EDX analyses showed abundant oxygen atoms on the caffeine carbon dot-supported Co catalyst. It can be attributed to the prevention of aggregation of particles by reducing the average particle size with both caffeine and carbon quantum dots materials. The catalysts prepared in methanol and ethanol solvent by hydrothermal treatment compared to water have significant effects on H2 production from KBH4 hydrolysis. The H2 production rate obtained by Co@MOF-CQD (ethanol) at 30 degrees C was 17,081 ml min-1g-1. At the same time, the TOF value obtained with 4% KBH4 for the Co@MOF-CQD (ethanol) was found as 2765 h-1. The reusability of Co@CQD-MOF(ethanol) for the catalytic hydrolysis of KBH4 for H2 production was evaluated by six consecutive experiments.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Hydrogen generation by hydrolysis of ammonia borohydride using the Nano-Bimetallic catalyst
(2021) Onat, Erhan; İzgi, Mehmet Sait
This study focuses on the hydrolysis of hydrogen productionparameters through the synthesized catalyst Co-Cr-B fromammonia borane using the low cost of cobalt (Co) andchromium (Cr). The synthesized Co-Cr-B catalyst wasinteracted with the ammonia borane solution. Later, optimumconditions for the hydrolysis of ammonia borane weredetermined at different catalyst amounts, NaOHconcentrations, catalytic activities, and temperatures. Reactionkinetics was examined using the data obtained, and theactivation energy of the reaction was determined as 22.30kJ.mol-1. The degree of reaction was in agreement with the 1stdegree.
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.
Hydrogen production mechanism and catalytic productivity of Ni-X@g-C3N4 (X = precious and non-precious promoter metals) catalysts from KBH4 hydrolysis under stress loading and atmospheric pressure: Experimental analysis and molecular dynamics approach
(Elsevier Science Sa, 2024) Celik, Fatih Ahmet; Aygun, Murat; Karabulut, Ezman; Onat, Erhan; Izgi, Mehmet Sait; Yilmaz, Muecahit; Ayguen, Zeynep
In this study, the pressure effect of Ni-based catalysts added a second promoter metal to increase of catalyst performance supported a graphite carbon nitride (g-C3N4) monolayer on hydrogen release mechanisms from potassium boron hydride (KBH4) hydrolysis was investigated using molecular dynamics (MD) method based on tight-binding density functional theory (DFT). The use of the various promoters, such as transition metals (X = Cu, Ta and W) and noble metals (X = Pd, Pt and Rh) with applying a high external pressure was investigated to understand the role on catalytic performance of the Ni-based catalysts under stress loading. The g-C3N4 monolayer doped with Ni-X nano-catalysts was used for efficient H-2 release from KBH4 hydrolysis. The computational results show that the number of H-2 shows more increment with MD time for NiW and NiRh catalysts than other NiTa and NiCu (transition metals) and NiPd and NiPt (noble metals) under 0 GPa pressure. On the other hand, a notable increase in H-2 amount is seen only NiCu and NiRh catalysts under 50 GPa. Also, the mechanism of the H-2 production reaction from KBH4 hydrolysis of g-C3N4 doped NiCo catalysts was clarified. High-performance cost metal catalysts such as NiCo was investigated as both experimentally and modeling under atmospheric pressure to enhance its commercial application value. Some experimental applications and analyzes were also performed to measure the accuracy of the modeling for the relevant molecular groups in the system.
Influence of the using of methanol instead of water in the preparation of Co-B-TiO2 catalyst for hydrogen production by NaBH4 hydrolysis and plasma treatment effect on the Co-B-TiO2 catalyst
(Pergamon-Elsevier Science Ltd, 2016) Sahin, Omer; Izgi, M. Sait; Onat, Erhan; Saka, Cafer
In this work, methanol was used as an alternative to water. Our objective is to study the influence of the using of methanol instead of water in the preparation of Co-B-TiO2 catalyst. It is also expected to improve the activity of Co-B-TiO2 catalyst by plasma treatment for the hydrogen generation from hydrolysis of NaBH4. The prepared catalysts were characterized using BET (N-2 adsorption), SEM (scanning electron microscopy), XRD (X-ray diffraction) and FTIR (Fourier transform infrared) methods. The Co-B-TiO2 catalyst prepared in methanol shows maximum hydrogen generation rate, which is about 3.0 times higher than that obtained for Co-B-TiO2 catalyst prepared in water. The maximum hydrogen generation rates for the Co-B-TiO2 catalysts prepared in water and methanol were 1017 and 3031 mL/min/g, respectively. In addition, the maximum hydrogen generation rates for the plasma treated Co-B-TiO2 catalysts prepared in water and methanol were 1320 and 2656 mL/min/g, respectively. The activation energies of nth-order reaction model for the hydrogen production from hydrolysis of NaBH4 with the plasma treated Co-B/TiO2 catalyst prepared in methanol and Co-B/TiO2 catalyst prepared in methanol can be obtained from the slope and intercept of the regression line, being 41.29 and 36.24 kJ/mol, respectively. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Influence of the using of methanol instead of water in the preparation of Co–B–TiO2 catalyst for hydrogen production by NaBH4 hydrolysis and plasma treatment effect on the Co–B–TiO2 catalyst
(Elsevier-International Journal of Hydrogen Energy, 2016) Şahin, Ömer; İzgi, M.Sait; Onat, Erhan; Saka, Cafer
In this work, methanol was used as an alternative to water. Our objective is to study the influence of the using of methanol instead of water in the preparation of Co–B–TiO2 catalyst. It is also expected to improve the activity of Co–B–TiO2 catalyst by plasma treatment for the hydrogen generation from hydrolysis of NaBH4. The prepared catalysts were characterized using BET (N2 adsorption), SEM (scanning electron microscopy), XRD (X-ray diffraction) and FTIR (Fourier transform infrared) methods. The Co–B–TiO2 catalyst prepared in methanol shows maximum hydrogen generation rate, which is about 3.0 times higher than that obtained for Co–B–TiO2 catalyst prepared in water. The maximum hydrogen generation rates for the Co–B–TiO2 catalysts prepared in water and methanol were 1017 and 3031 mL/min/g, respectively. In addition, the maximum hydrogen generation rates for the plasma treated Co–B–TiO2 catalysts prepared in water and methanol were 1320 and 2656 mL/min/g, respectively. The activation energies of nth-order reaction model for the hydrogen production from hydrolysis of NaBH4 with the plasma treated Co–B/TiO2 catalyst prepared in methanol and Co–B/TiO2 catalyst prepared in methanol can be obtained from the slope and intercept of the regression line, being 41.29 and 36.24 kJ/mol, respectively.
Investigation of high catalytic activity catalyst for high hydrogen production rate: Co-Ru@MOF
(Springer, 2021) Onat, Erhan; Cevik, Sabri; Sahin, Omer; Horoz, Sabit; Izgi, Mehmet Sait
We report the synthesis of metal-organic framework supported-Co-Ru (Co-Ru@MOF) catalyst and its catalytic activity. The synthesized Co-Ru@MOF catalyst for the first time is used to obtain the maximum hydrogen production rate from hydrolysis of NaBH4. The synthesized Co-Ru@MOF catalyst indicates a compelling performance in the hydrogen production from the hydrolysis of NaBH4. It is found that Co-Ru@MOF with the loading of Co (80 wt%) and Ru (20 wt%) indicates a high hydrogen production rate of 15,144 mL/min.g and low activation energy of 41.41 kJ mol(-1). The current study demonstrates that MOF is promising support for dispersing metal catalysts. Moreover, the synthesized Co-Ru@MOF catalyst is characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersion spectroscopy (EDS) measurements.
Karbon kuantum noktacıklar ile desteklenmiş nanopartiküllerin sentezi yapısal tanımlamaları ve farklı hidrojen kaynaklarından hidrojen üretimi için hidroliz tepkimelerindeki katalitik performanslarının ölçülmesi
(Siirt Üniversitesi, 2022) Onat, Erhan; İzgi, Mehmet Sait; Şahin, Ömer
Bu tez çalışmasında üç farklı hidrojen kaynağından özgün bir şekilde üretilmiş karbon kuantum noktacık destekli homojen ve heterojen katalizör yapıları aracılığıyla hidrolizle hidrojen üretimi katalitik parametrelerinin incelenmesi amaçlanmıştır. Bunun için hidrotermal yöntemle iki organik bileşik kaynağından karbon kuantum noktacık sentezi sağlanmıştır. Bu noktacıklara kobalt, nikel ve rutenyum metalleri farklı şekillerde yüklenerek homojen ve heterojen katalizör yapıları (Co@CQDs, Ni@CQDs, Ru@CQDs ) sentezlenmiştir. Sentezlenen karbon kuantum noktacık ve katalizör yapıları; TEM, XRD, XPS, ICP-MS, EDX, BET ve UV ile tanımlanmıştır. Sentez ve tanılama işlemlerinden sonra her bir katalizör yapısının sodyum borhidrür, potasyum borhidrür, ve amonyak boran sulu çözeltilerinin katalitik hidrojen üretim performansı ölçülerek, tepkime kinetiği incelenmiştir. Tez çalışması kapsamında karbon kuantum noktacık destekli Co, Ni ve Ru metalleri bazlı monometalik 11 özgün katalizör yapısı sentezlenmiştir. Bu katalizörlerin üç farklı hidroliz kaynağı ile 30 hidroliz katalitik bozunma tepkimesi incelenmiştir. Katalizör çevrim frekansı (TOF) ve hidrojen üretim hızları hesaplamaları sonucunda çok yüksek değerlerde katalitik etki gösteren katalizör malzeme yapısının sentezlendiği anlaşılmıştır.
KOBALT BAZLI BİMETALİK NANOKATALİZÖRÜN POTASYUM BORHİDRÜR HİDROLİZ TEPKİMESİ ÜZERİNDEKİ KATALİTİK ETKİSİNİN İNCELENMESİ
(2021) Onat, Erhan; Aslan, Mehmet; İzgi, Mehmet Sait
Hidrojen depolamada kullanılan bor kaynaklı bileşiklerin başında metal hidrürler gelmektedir. Bu bileşiklerden potasyum borhidrür; düşük maliyetli olması, zehirli olmaması, yüksek sıcaklıklarda kararlı olması vb. özelliklerinden dolayı önemli bir hidrojen depolama kaynağıdır. Hidroliz sonucunda kendi yapısındaki hidrojen kadar hidrojenin sudan temin edilmesini sağlayan potasyum borhidrür, hidrojen kaynağı olarak kullanılması durumunda birçok avantaj sağlamaktadır. Bu çalışmada, potasyum borhidrür hidrolizinde kullanılmak üzere kobalt (Co) ve kromdan (Cr) sentezlenen bimetalik nanokatalizörün katalitik parametreleri incelenmiştir. Katalizör sentezi ve etkisi için sırasıyla metal birleşme oranı, çözücü ortamı, katalizör miktarı, potasyum borhidrür konsantrasyonu ve sıcaklık parametreleri ışığında hidroliz tepkimesi optimum verileri elde edilmiştir. En iyi şartlarda hidrojen üretim hızı 2448,24 mL/g.min olarak belirlenmiştir. Katalizör performansını belirlemek üzere yapılan tekrarlı kullanımlar sonucunda 8. Kullanıma kadar %100 ürün veriminin sağlandığı belirlenmiştir. Tepkime kinetiği incelendiğinde tepkimenin 0. Dereceden olduğu, tepkime aktivasyon enerjisinin ise 41,3 kJ/mol olduğu belirlenmiştir. Çalışma sonucu olarak yakıt hücrelerinde hidrojen kaynağı olarak potasyum borhidrürün kullanılması durumunda hidrojen üretimi için Co-Cr katalizörünün kullanımının yerinde olacağı değerlendirilmektedir. Potasyum borhidrür, diğer hidrojen depolama özelliğindeki bileşiklere göre daha az oranda hidrojen depoladığından bugüne kadar çok araştırılmamıştır. Fakat bu çalışmada görüldüğü gibi hidrolizi sonucunda yüksek oranda hidrojen üretimi sağlanmıştır. Dolayısıyla, ileriki süreçte benzer çalışmalarla çokça karşılaşılması beklenmektedir.
Molecular dynamics approach to efficient hydrogen generation process of Co-B catalysts decorating lanthanides (La, Ce, Pr, Nd) supported by flat-sheet and twisted ThMoB4-type graphene from NaBH4 hydrolysis: Insights from non-self-consistent GFN1-xTB method
(Elsevier Science Sa, 2024) Celik, Fatih Ahmet; Karabulut, Ezman; Onat, Erhan; Izgi, Mehmet Sait; Yilmaz, Mucahit
In this study, the promoter role on highly efficient hydrogen generation productivity and H-2 formation mechanisms of Co-B-X catalysts modified by rare earths (X = La, Ce, Pr, Nd) supported by flat-sheet and twisted ThMoB4-type graphene from sodium borohydride (NaBH4) hydrolysis was investigated using molecular dynamics (MD) method based on non-self-consistent tight binding GFN1-xTB Method. The twisted ThMoB4-type graphene layer was constructed by adsorbing of ethylene carbonate (EC) molecule on armchair site of graphene surface with applying of geometric optimization process. The addition of Nd to CoB exhibited to higher H-2 release compared to other CoB containing lanthanides (La, Ce and Pr) both flat-sheet and twisted ThMoB4-type graphene. While the number of H-2 for Co-B-Nd is 14, the H-2 amount is only 8 for Co-B-Ce supported flat-sheet graphene at the end of simulation time. Also, the placing of twisted graphene instead of flat-sheet in the catalytic complex led to about 36 % increase in H-2 number for Co-B-Nd. The computational results revealed that the availability of the active sites, such as basicity of catalytic environment related to OH and H species and the mobility of Co atom, played an important role for catalytic activity and performance for H-2 production. This work can provide new insight for experimental studies of Co-B-X (X = La, Ce, Pr, Nd) catalysts for hydrogen production in atomic-level and the creation of new hydrogen energy applications and facilitates for H-2 generation efficiency.
Nickel/nickel oxide nanocomposite particles dispersed on carbon quantum dot from caffeine for hydrogen release by sodium borohydride hydrolysis: Performance and mechanism
(Elsevier Science Sa, 2024) Onat, Erhan; Izgi, Mehmet Sait; Sahin, Omer; Saka, Cafer
The political and economic problems caused by the limited use of fossil fuels are another important reason that leads people to alternative energy sources. Compared to other energy sources, hydrogen has the potential to be the energy source of the future. In this study, the preparation of Ni/NiO doped caffeine-based carbon dot(CCQD) for efficient hydrogen (H2) production from the hydrolysis of sodium borohydride (NaBH4) is included the fabrication of nanoscale caffeine-based carbon quantum dot, the preparation of the CCQD-supported Ni/NiO catalyst as boron-free and the preparation of the CCQD-supported Ni/NiO catalyst by hydrothermal treatment in ethanol solvent (NiO@ CCQD-HT (EtOH)). The HGR values obtained with NiO@CCQD-HT (EtOH) was 16,819 ml min- 1gcat- 1. Moreover, the turnover frequency (TOF) value for the NiO@CCQD-HT (EtOH) was found as 2315 h-1. The activation energy (Ea) for the NiO@CCQD-HT (EtOH) catalyst was 39.48 kJmol-1.
Revolutionary carbon quantum dot supported-Co catalyst for record-breaking hydrogen production rate
(Springer, 2024) Onat, Erhan; Horoz, Sabit; Sahin, Omer; Izgi, Mehmet Sait
In this study, we introduce a groundbreaking approach in the field of hydrogen production by synthesizing and characterizing a carbon quantum dot supported-Co (Co-B_CQDs) catalyst. Our results demonstrate that this state-of-the-art catalyst exhibits exceptional performance in the hydrolysis of KBH4, resulting in a record-breaking hydrogen production rate of 23,019.97 mL*gcat(-1)*min(-1) and a remarkably low activation energy of 19.36 kJ/mol. This is the first time that this type of catalyst has been used to achieve such outstanding results. The study highlights the remarkable potential of carbon quantum dots as a support material for dispersing metal catalysts, which opens up new avenues for research in the field of hydrogen production. The synthesized catalyst was extensively characterized using various analytical techniques such as X-ray diffraction (XRD), ultraviolet and visible light (UV-Vis), photoluminescence (PL), and inductively coupled plasma optical emission spectrometry (ICP-OES) measurements, which further confirmed its superior performance.

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