Browsing by Author "Top, Tuba"

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Carbon Supported Nico Alloy Nanoclusters: Synthesis, Charactarization and Their Catalytic Application in the Methanolysis of the Ammonia Borane
(2021) Top, Tuba; Zahmakıran, Mehmet
Karbon destekli oleylamin ile kararlaştırılmış bimetalik NiCo(0) nanokümeleri (NiCo@C) kolladial yöntem ile hazırlandı. Elde edilen NiCo@C malzemesinin tanımlanması ICP-OES, P-XRD, XPS, TEM gibi ileri analitiksel yöntemler kullanılarak gerçekleştirildi. Yapılan tanımlama sonuçları bize ortalama parçacık boyutları 5.11 ± 0.54 nm olan bimetalik NiCo nanokümelerinin aktif karbon yüzeyinde oluştuğunu göstermiştir. NiCo@' un katalitik performansı, etkinlik ve kararlılık açısından uygun koşullar altında (25 °C) amonyak boranın (NH3BH3) metanoliz tepkimesinde incelendi. Ni0.19Co0.81@C katalizörü yüksek dönüşümde (%100) ve 136.65 dak-1 çevrim frekansı ile amonyak boranın metanoliz tepkimesini katalizlediğini tespit ettik. Ayrıca, aktif karbon destekli bimetalik NiCo nanokümelerinin sızma ve sinterleşmeye karşı oldukça kararlı olduğu bulundu, bu da Ni0.19Co0.81@C katalizörünün etkinliğini kaybetmeksizin amonyak boran metanoliz tepkimesinde tekrar kullanılabilir heterojen katalizör olduğunu göstermektedir.
Complete Dehydrogenation of Hydrazine Borane on Manganese Oxide Nanorod-Supported Ni@ir Core-Shell Nanoparticles
(Amer Chemical Soc, 2020) Yurderi, Mehmet; Top, Tuba; Bulut, Ahmet; Kanberoglu, Gulsah Saydan; Kaya, Murat; Zahmakiran, Mehmet
Hydrazine borane (HB; N2H4BH3) has been considered to be one of the most promising solid chemical hydrogen storage materials owing to its high hydrogen capacity and stability under ambient conditions. Despite that, the high purity of hydrogen production from the complete dehydrogenation of HB stands as a major problem that needs to be solved for the convenient use of HB in on-demand hydrogen production systems. In this study, we describe the development of a new catalytic material comprised of bimetallic Ni@Ir core-shell nanoparticles (NPs) supported on OMS-2-type manganese oxide octahedral molecular sieve nanorods (Ni@Ir/OMS-2), which can reproducibly be prepared by following a synthesis protocol including (i) the oleylamine-mediated preparation of colloidal Ni@Ir NPs and (ii) wet impregnation of these ex situ synthesized Ni@Ir NPs onto the OMS-2 surface. The characterization of Ni@Ir/OMS-2 has been done by using various spectroscopic and visualization techniques, and their results have revealed the formation of well-dispersed Ni@Ir core-shell NPs on the surface of OMS-2. The catalytic employment of Ni@Ir/OMS-2 in the dehydrogenation of HB showed that Ni-0.22@Ir-0.78/OMS-2 exhibited high dehydrogenation selectivity (>99%) at complete conversion with a turnover frequency (TOF) value of 2590 h(-1) at 323 K, which is the highest activity value among all reported catalysts for the complete dehydrogenation of HB. Furthermore, the Ni-0.22@Ir-0.78/OMS-2 catalyst enables facile recovery and high stability against agglomeration and leaching, which make it a reusable catalyst in the complete dehydrogenation of HB. The studies reported herein also include the collection of wealthy kinetic data to determine the activation parameters for Ni-0.22@Ir-0.78/OMS-2-catalyzed dehydrogenation of HB.
Preparation of Carbon-Supported Nico Alloy Nanoparticles and Evaluation of Their Catalytic Activity in the Methanolysis of Ammonia Borane
(Elsevier Sci Ltd, 2023) Top, Tuba; Yurderi, Mehmet; Bulut, Ahmet; Karakoyun, Necdet; Ceylan, Esra; Zahmakiran, Mehmet
The present work reported the development of carbon-supported bimetallic NiCo nanoparticles for H2 production in the methanolysis of AB for electricity generation from fuel cells. It was investigated by powder X-ray diffraction (P-XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. The catalytic properties of the Ni0.19Co0.81/C catalyst were carefully evaluated in terms of catalytic performance, such as different temperatures, metal [NiCo] loadings, substrate [AB] concentrations, and recyclability in 10 runs. The resulting N0.19Co0.81/C catalyst exhibits good catalytic activity with a high initial TOF of 136.65 min-1 and activation energy of 33.38 kJ mol- 1 for AB methanolysis. Moreover, in the recyclability test, the Ni0.19Co0.81/C catalyst maintained 95 % of its initial activity with 100 % conversion after ten runs.