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Öğe Bimetallic nanomaterials for direct alcohol fuel cells(Elsevier, 2021) Göksu, Haydar; Bekmezci, M.; Erduran, Vildan; Şen, FatihNanoscience and nanotechnology have grown tremendously in the 21st century. Fascinating advances in nanostructured materials have been happening more and more. A lot of applications have been made in the areas of health, defense, energy, materials chemistry, and even biology. These studies have been increasing gradually. However, sometimes monometallic materials cannot provide the desired cycle efficiency. Due to this situation, bimetallic nanomaterials have come to the fore. Among various liquid alcohol fuels, methanol is a promising fuel candidate due to its high energy density, ease of use, low operating cost. This fuel candidate is getting more and more attention from researchers. The development of electrocatalysts for direct methanol fuel cells (DMFCs) is highly valuable, with new-generation catalysts being developed. For this purpose, bimetallic materials and catalysts were synthesized. Bimetallic nanomaterials are nanoparticles containing two different types of metal atoms in a single material; they are considered heterogeneous catalysts. Bimetallic nanoparticles have many reactive functions, especially in organic chemistry. Also, extensive mechanical studies have been performed in applications ranging from sensors to catalysts. Those nanomaterials have superior and unique properties compared to ordinary materials, and therefore they have been used for the improvement of the new catalyst system with increased efficiency, activity, stability, durability, reusability, and selectivity. Sinfelt introduced the term “bimetallic” at the beginning of the 1980s. The superior properties of bimetallic nanomaterials can be explained by their synergistic effects. In this chapter, information about bimetallic nanomaterials is given, as well as about alcohol oxidation of these particles. © 2021 Elsevier Inc. All rights reserved.Öğe Composites of Palladium-Nickel Alloy Nanoparticles and Graphene Oxide for the Knoevenagel Condensation of Aldehydes with Malononitrile(Amer Chemical Soc, 2019) Lolak, Nabih; Kuyuldar, Esra; Burhan, Hakan; Göksu, Haydar; Akocak, Süleyman; Şen, FatihHerein, we have described uniformly dispersed palladium-nickel nanoparticles furnished on graphene oxide (GO-supported PdNi nanoparticles) as a powerful heterogeneous nanocatalyst for the promotion of Knoevenagel reaction between malononitrile and aromatic aldehydes under mild reaction conditions. The successful characterization of PdNi nanoparticles on the GO surface was shown by X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and TEM. GO-supported PdNi nanoparticles, which are used as highly efficient, stable, and durable catalysts, were used for the first time for the Knoevenagel condensation reaction. The data obtained here showed that the GO-supported PdNi nanocatalyst had a unique catalytic activity and demonstrated that it could be reused five times without a significant decrease in the catalytic performance. The use of this nanocatalyst results in a very short reaction time under mild reaction conditions, high recyclability, excellent catalytic activity, and a straightforward work-up procedure for Knoevenagel condensation of malononitrile and aromatic aldehydes.Öğe Eco-friendly hydrogenation of aromatic aldehyde compounds by tandem dehydrogenation of dimethylamine-borane in the presence of a reduced graphene oxide furnished platinum nanocatalyst(Royal Soc Chemistry, 2016) Göksu, Haydar; Yıldız, Yunus; Çelik, Betül; Yazıcı, Melike; Kılbaş, Benan; Şen, FatihIn this study, highly monodisperse platinum nanoparticles supported on reduced graphene oxide in the presence of tripentylamine (TPA) (Pt(0)/TPA@rGO NPs) are used as a stable, isolable, bottleable, long-lived, highly efficient and exceptionally reusable heterogeneous catalyst for eco-friendly hydrogenation of various aromatic aldehyde compounds with unprecendented catalytic performance. Pt(0)/TPA@rGO NPs have been used for the first time for these types of synthesis reactions and these NPs were characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Herein, the catalyst has been used for tandem dehydrogenation of dimethylamine-borane (DMAB) and hydrogenation of aromatic aldehyde compounds in aqueous methanol at room temperature in reaction times ranging from 1.0 to 25 min with yields reaching up to 95%. The presented catalytic methodology is highly efficient as well as having exceptional reusability performance. This process can be assessed as an eco-friendly method with both a reusable reduced GO-supported platinum nanocatalyst and a hydrogen source (DMAB).Öğe Handy and highly efficient oxidation of benzylic alcohols to the benzaldehyde derivatives using heterogeneous Pd/AlO(OH) nanoparticles in solvent-free conditions(Nature Research, 2020) Göksu, Haydar; Şen, FatihThe selective oxidation of benzylic alcohols was performed by using commercially available aluminum oxy-hydroxide-supported palladium (Pd/AlO(OH)) nanoparticles (0.5 wt.% Pd, about 3 nm size) under mild conditions. The oxidation method comprises the oxidation of benzyl alcohols catalyzed by aluminum oxy-hydroxide-supported palladium under ultrasonic and solvent-free conditions and a continuous stream of O2. The characterization of aluminum oxy-hydroxide-supported palladium nanocatalyst was conducted by several advanced analytical techniques including scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and elemental analysis by ICP-OES. The oxidation of a variety of benzyl alcohol compounds were tested by the aluminum oxy-hydroxide-supported palladium nanoparticles, and all expected oxidation products were obtained by the high conversion yields within 3 hours. The reaction progress was monitored by TLC (Thin-layer chromatography), and the yields of the products were determined by 1H-NMR and 13C NMR analysis. © 2020, The Author(s).Öğe Highly Active and Reusable Pd/AlO(OH) Nanoparticles for the Suzuki Cross-Coupling Reaction(Bentham Science Publ Ltd, 2018) Göksu, Haydar; Zengin, Nursefa; Karaosman, Arife; Şen, FatihBackground: Biphenyl derivatives are an important component of many natural products and used in the treatment of conditions such as anxiety disorders, infections, and insomnia. In addition, the synthesis of these molecules is very important due to their kinase inhibitory effect as well as their antibacterial and antifungal effects. In this study, highly efficient and reusable Pd/AlO(OH) Nanoparticles (NPs) were used as an alternative heterogeneous catalysts system for the coupling reactions. Methods: Pd/AlO(OH) Nanoparticles (NPs) was characterized by SEM, XRD and TEM. Later, Pd/AlO(OH) nanoparticles were performed for coupling reactions. At the end of the reaction, the main products were checked with GC and the GC yield calculated. The desired biaryl products were successfully obtained within 2 h with good yields in the presence of Pd/AlO(OH) nanoparticles. Results: The morphologies of the Pd/AlO(OH) NPs were characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The determination of the appropriate reaction conditions for the desired biaryl products is of crucial importance for successful synthesis. For this purpose, optimization of the conditions for conversion of iodobenzene to biphenyl. was carried out in detail. The reusability of the PdAlO(OH) NPs was also examined for Suzuki Cross-Coupling Reaction. On the other hand, the high temperature and type of catalyst are the factors that make it easier to reach the activation energy. For this reason, the comparison of the designed catalytic system with recently published works are given for Suzuki cross-coupling of bromobenzene with aryl boronic acid. Last but not least, the reaction mechanism of the Suzuki cross-coupling reaction has been entirely identified in the presence of PdAlO(OH) NPs. Conclusion: A novel method was developed for the synthesis of biphenyl derivatives in a short time with high yields by the help of Pd/AlO(OH) NPs at room temperature. As starting materials, neither phenylboronic acid, nor aryl halide derivatives are water soluble, so it was desirable to conduct the reactions in water/isopropyl alcohol as an eco-friendly solvent. Thus, the developed method is both ecofriendly and economical and can be considered as a viable alternative to prior methods appearing in the literature.Öğe Highly Efficient and Monodisperse Graphene Oxide Furnished Ru/Pd Nanoparticles for the Dehalogenation of Aryl Halides via Ammonia Borane(Wiley-V C H Verlag Gmbh, 2016) Göksu, Haydar; Yıldız, Yunus; Çelik, Betül; Yazıcı, Melike; Kılbaş, Benan; Şen, FatihHighly monodisperse graphene oxide-supported Ru/Pd nanoparticles (RuPd@GO NPs) have been reproducibly and easily synthesized by microwave assisted method. RuPd@GO NPs was performed for dehalogenation of arylhalides in the presence of ammonia borane in a mild condition as novel, highly efficient and exceptional reusable heterogeneous catalyst. The novel materials were characterized by transmission electron microscopy (TEM), the high resolution electron micrograph (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the prepared catalysts are highly crystalline, monodisperse and colloidally stable. The current one-pot catalytic process was described as a new methodology for dehalogenation of arylhalides which can be assessed as a quite simple, eco-friendly and highly efficient as well as exceptional reusable. All products were provided with one of the highest yield and the shortest time in the presence of novel RuPd@GO NPs due to the the synergistic effect of Ru and Pd. Our synthesis process comes with a facile and eco-friendly option to RuPd@GO NPs, allowing further scrutiny of current catalysts for numerous other chemical reactions.Öğe Metal Organic Frameworks Based Materials for Renewable Energy Applications(Materials Research Forum Llc, 2019) Göksu, Haydar; Zengin, Nursefa; Şen, FatihCrystalline metal-organic frames (MOFs) fall into the category of high potential porous materials that can be used in gas storage, adsorption / separation, adsorption as adsorbent, catalysis, magnetism, sensor design and drug delivery. MOFs are typically formed by self-assembly, where secondary building units (SBUs) are connected with organic ligands to form complex networks. Organic ligands or metallic SBUs may be modified to be critical for their functionality and utility for specific applications in order to control the porosity of MOFs. MOFs are used in renewable energy and environmental applications, application of hydrogen energy, hydrogen storage, storage and conversion of CO2, biogas production, thermal energy storage, rechargeable batteries and supercapacitors and in dye sensitized solar cells.Öğe A novel thiocarbamide functionalized graphene oxide supported bimetallic monodisperse Rh-Pt nanoparticles (RhPt/TC@GO NPs) for Knoevenagel condensation of aryl aldehydes together with malononitrile(Elsevier, 2018) Şen, Betül; Akdere, Esma Hazal; Şavk, Aysun; Gültekin, Emine; Paralı, Özge; Göksu, Haydar; Şen, FatihFunctionalization of the graphene provides various possibilities to improve the use of the graphene and to provide more chemical conversion to the graphene. In order to enhance its chemical and physical properties, the graphite which is mainly functionalized with heteroatom-based functional groups is followed intensively, but often results in the inoculation of heteroatoms as various functional groups. Here we show that the graphene oxide can be mainly functionalized with a single species of sulfur and can be reduced to form a graphene which is ftmctionalized with monothiol at the same time. By the help of thiocarbamide-functionalized graphene oxide (TC@GO) the monodisperse rhodium/platinum nanoparticles (RhPt/TC@GO NPs) have been synthesized as promising catalysts for the Knoevenagel condensation to benzylidenemalononitrile derivatives of aryl aldehydes. The monodisperse RhPt/TC@GO NPs have been prepared via a facile method. The novel thiocarbamide-functionalized graphene oxide (TC@GO) supported rhodium/platinum nanoparticles (RhPt/TC@GO NPs) are identified by characterization techniques such as the Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The spectroscopic and morphological studies of the monodisperse RhPt/TNM@GO NPs indicate the highly crystalline form, well dispersity, ultrafine structure and colloidally stable NPs. After fully characterization of prepared nanoparticles, the novel nanocatalysts have been tried for the Knoevenagel condensation to benzylidenemalononitrile derivatives of aryl aldehydes and show excellent catalytic activity and a yield over 99% by the reaction at room temperature within 8-35 min in the presence of malononitrile and derivatives of aldehyde. As a result, the prepared nanocomposites exhibit very good heterogeneous catalyst properties for Knoevenagel condensation reactions.Öğe One-pot synthesis of Hantzsch dihydropyridines using a highly efficient and stable PdRuNi@GO catalyst(Royal Soc Chemistry, 2016) Demirci, Tuna; Çelik, Betül; Yıldız, Yunus; Eriş, Sinan; Arslan, Mustafa; Şen, Fatih; Kılbaş, BenanAddressed herein, highly monodispersed PdRuNi nanoparticles furnished with graphene oxide (PdRuNi@GO NPs) were prepared as novel, stable, efficient and exceptionally reusable heterogeneous catalysts for 1,4-dihydropyridine synthesis via multicomponent condensation reactions of various aldehydes with dimedone, ammonium acetate and ethyl acetoacetate at 70 degrees C in DMF with efficient catalytic performance. These synthesized novel materials were characterized by transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). This presented one pot catalytic process is described as a new methodology of the Hantzsch synthesis, which can be assessed as quite simple and efficient as well as exceptionally reusable. At the end of the reaction, one of the highest yields and the shortest times were obtained for the model reaction in the presence of novel monodisperse PdRuNi@GO NPs.Öğe Oxidation of Benzyl Alcohol Compounds in the Presence of Carbon Hybrid Supported Platinum Nanoparticles (Pt@CHs) in Oxygen Atmosphere(Nature Research, 2020) Göksu, Haydar; Burhan, Hakan; Mustafov, Sibel Demiroğlu; Şen, FatihA novel catalyst which carbon hybrid supported platinum nanoparticles were synthesized by our group for the oxidation of benzyl alcohol derivatives. In this study, this catalyst was utilized for the oxidation of benzyl alcohol derivatives to benzaldehyde compounds in aqueous toluene at 80 °C. The benzaldehyde derivatives were synthesized in high yields and mild conditions in the presence of the catalyst by the developed method. Additionally, the prepared nanoparticles have been characterized by Transmission Electron Microscopy (TEM), the high-resolution electron micrograph (HR-TEM), X-ray Photoelectron Spectroscopy (XPS), and X-ray Diffraction (XRD). The mean particle size of the nanoparticles determined by the XRD technique was found to be 2.83 nm in parallel with TEM analysis. TEM analysis also indicated that the Pt nanoparticles were evenly dispersed on the support material. Finally, the Pt@CHs catalyst was shown also stable and reusable for the oxidation reaction, providing ?95% conversion after its 3rd consecutive use in the oxidation reaction of various compounds. © 2020, The Author(s).Öğe Polymer-based nanocatalyts for alcohol fuel cells(Elsevier, 2021) İşler, İlyas İlker; Göksu, Haydar; Erduran, Vildan; Işık, İskender; Şen, FatihToday, changes in industrialization and technology in the globalized world are increasing the energy consumption needs of countries throughout the world. The gradual decrease in the fossil fuels that humans use to meet their energy needs, fueled by increasing oil prices and damage to the environment have led the scientific community to search for alternative energy sources. This has led to the discovery and implementation of new energy sources for the first time, as well as a reconsideration of the efficiency of previously known power generation devices, such as fuel cells. In general terms, a fuel cell qualifies as a system in which fuel can be converted directly into energy without any intermediate processing. Over the past several decades, studies on the efficiency of fuel cells have focused on the type of fuel and the catalyst material used. Similarly, in recent research, the effect on the efficiency of fuel cells has been reevaluated for different catalysts, and the factors affecting the performance of fuel cells and fuel cells, including the effects of polymer-containing nanocatalysts that increase efficiency and reduce costs, were discussed. In addition, the potential of environmentally friendly, low-emission, and cost-reducing effects of new-generation fuel cells were investigated. In this chapter, polymer-based nanocatalyts for alcohol fuel cells will be introduced and examined individually, various membrane properties and application methods will be discussed, and the basic principles of the application of these fuel cells will be shown. © 2021 Elsevier Inc. All rights reserved.Öğe Recent Advances in the Reduction of Nitro Compounds by Heterogenous Catalysts(Bentham Science Publ Ltd, 2017) Göksu, Haydar; Sert, Hakan; Kılbaş, Benan; Şen, FatihAmines which are organic molecules can be employed in several significant syntheses such as the synthesis of biologically active molecules, polymers, drugs, dyes and pharmaceutical products. The critical issue in the synthesis of amines is to choose the most efficient heteregenous catalyst in order to obtain the best catalytic activity, reusability and durability. For this purpose, up to know, many studies have been performed on the reduction of nitro compounds to synthesize amines in the presence of various heteregenous catalysts. Addressed herein, recent developments have been gathered on the production of amines by the help of heteregenous catalysts such as platinum-, gold-, palladium-, silver-, nickel-, iron-, copper-, ruthenium-, iridium-, rhodium-, ionic liquid- and carbon-based monometallic, bimetallic and multimetallic heterogenous catalysts. Those catalysts have showed superior characteristics in terms of the amount, recoverability, reusability and the structural integrity of catalyst during the reaction. Thus, the main goal of this study is to enlighten the scientists and to discuss (review) the critical investigations on the reduction of nitro groups by heterogenous catalysts in last years.Öğe Superior Monodisperse CNT-Supported CoPd (CoPd@CNT) Nanoparticles for Selective Reduction of Nitro Compounds to Primary Amines with NaBH4 in Aqueous Medium(Wiley-V C H Verlag Gmbh, 2016) Göksu, Haydar; Çelik, Betül; Yıldız, Yunus; Şen, Fatih; Kılbaş, BenanSuperior carbon nanotube furnished CoPd (CoPd@CNT) nanoparticles (NPs) were reproducibly and easily produced by sonochemical double solvent reduction method in a mild condition and the size of the CoPd NPs was found as 3.63 nm. The prepared novel catalyst were characterized by transmission electron microscopy (TEM), the high resolution electron micrograph (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The sum of their results showed the formation of highly crystalline, monodisperse and colloidally stable CoPd@CNT. The catalytic performance of these novel NPs were investigated for the first time for highly selective reduction to -NO2 unlike -CN groups, in which they were found to be exceptional reusable, isolable, stable and highly efficient heterogeneous catalyst. All prepared products were obtained with perfect yield by using CoPd@CNT as a heterogeneous catalyst and NaBH4 as a hydrogen source. Our synthesis process provides a facile and eco-friendly route to CoPd@CNT, allowing further investigation of current catalysts for many other chemical reactions.Öğe Synthesis and Characterization of Nearly Monodisperse Pt Nanoparticles for C-1 to C-3 Alcohol Oxidation and Dehydrogenation of Dimethylamine-borane (DMAB)(Amer Scientific Publishers, 2016) Erken, Esma; Yıldız, Yunus; Kılbaş, Benan; Şen, FatihHighly efficient nearly monodisperse Pt NPs catalyze C1 to C3 alcohol oxidation with very high electrochemical activities and provides one of the highest catalytic activities (TOF = 21.50 h(-1)) in the dehydrogenation of DMAB at room temperature. The exceptional stability towards agglomeration, leaching and CO poisoning for the prepared catalyst allow these particles to be recycled and reused in the catalysis of both DMAB dehydrogenation and C1 to C3 alcohol oxidation. After four subsequent reaction and recovery cycles, catalyst retained >= 80% activity towards the complete dehydrogenation of DMAB. The prepared catalyst structures were determined by the X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) respectively.Öğe The synthesis and characterization of size-controlled bimetallic nanoparticles(Elsevier, 2021) Göksu, Haydar; Bekmezci, M.; Bayat, R.; Altuner, E.E.; Şen, FatihBimetallic nanoparticles, having a different type, size, and structure, can be fabricated using two different metals and supporting materials. The combination of the two metals in different ratios and distributions is effective in forming bimetallic nanoparticles. The properties of the nanoparticles that can be used in many applications can be changed depending on the proportion of the metals, so nanoparticles exhibiting different features can be used in a number of appropriate areas. The nanoparticles obtained by mixing metals in different proportions can create a brand new feature that is not found in individual metals. Bimetallic nanoparticles have some uniques properties that are not seen in monometallic nanoparticles. Bimetallic nanoparticles, with their controllable crystal particle size, geometry, and magnetic properties can be utilized in many fields, such as catalytic, biosensors, water purification, and drug delivery. © 2021 Elsevier Inc. All rights reserved.
