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Article Citation - WoS: 23Citation - Scopus: 27Nanocrystalline Metal Organic Framework (mil-101) Stabilized Copper Nanoparticles: Highly Efficient Nanocatalyst for the Hydrolytic Dehydrogenation of Methylamine Borane(Elsevier Science Sa, 2018) Baguc, Ismail Burak; Ertas, Ilknur Efecan; Yurderi, Mehmet; Bulut, Ahmet; Zahmakiran, Mehmet; Kaya, MuratThe copper nanoparticles stabilized by nanocrystalline MIL-101 framework (Cu/nano-MIL-101) was reproducibly prepared by following double solvent method combined with liquid phase chemical reduction technique. The characterization of the resulting new material was done by using various analytical techniques including ICP-OES, P-XRD, N-2-adsorption-desorption, XPS, FE-SEM, SEM-EDX, BFTEM and HAADF-STEM; the summation of their results reveals that the formation of well-dispersed and very small sized (0.8 nm) copper nanoparticles within nanocrystalline MIL-101 framework. The catalytic performance of Cu/nano-MIL-101 in terms of activity and stability was tested in the hydrolytic dehydrogenation of methylamine borane (CH3NH2BH3), which has been considered as one of the attractive materials for the efficient chemical hydrogen storage. Cu/nano-MIL-101 catalyzes the hydrolytic dehydrogenation of methylamine borane with high activity (turnover frequency; TOF = 257 mot H-2/mol Cu x h) and conversion ( > 99%) under air at room temperature. Moreover, these nano-MIL-101 framework stabilized copper nanoparticles show great durability against to sintering and leaching, which make Cu/nano-MIL-101 reusable nanocatalyst in the hydrolytic dehydrogenation of methylamine-borane. Cu/nano-MIL-101 nanocatalyst retains 83% of its inherent activity at complete conversion even at 10th recycle in the hydrolytic dehydrogenation of methylamine borane.Article Polysulfur Copolymer as a Support Material for the Preparation of a Novel Multifunctional Photocatalytic Composite Material(Springer, 2025) Kesimal, Busra; Guner, Zuhal Vanli; Cihaner, Atilla; Kaya, MuratOne-step addition of magnetic nanoparticles and titanium dioxide nanoparticles into polysulfur copolymer as cheap and available support was reported for the first time to prepare the magnetically separable heterogeneous catalyst, PolyS-MNP-TiO2. The photocatalytic activities of the PolyS-MNP-TiO2 composite material and its constituents were examined in the methylene blue (MB) degradation, textile-based wastewater simulant, exposed to solar light. Detailed characterization of the catalysts was performed with SEM, TEM, and EDX measurements. The photocatalytic activity of the resulting composite was figured out in the removal of methylene blue dye by using a solar simulator. Significantly, the as-prepared PolyS-MNP-TiO2 exhibits exceptional photocatalytic activity and total degradation of dye molecules was achieved in 60 min. Additionally, the prepared novel photocatalyst showed enhanced stability and reusability due to the magnetic behavior of the composite material and the same portion of catalyst was used in five successive tries without apparent loss in catalytic activity by eliminating long and work-loaded processes like filtration and centrifugation.Article Citation - WoS: 28Citation - Scopus: 30Functionalized Polysulfide Copolymers With 4-Vinylpyridine Via Inverse Vulcanization(Elsevier Science Bv, 2019) Berk, Hasan; Balci, Burcu; Ertan, Salih; Kaya, Murat; Cihaner, AtillaA new series of functional polysulfide copolymers called poly(sulfur-random-4-vinylpyridine) (poly(S-r-4VP)) was synthesized via inverse vulcanization technique by ring opening polymerization of elemental sulfur in the presence of 4-vinylpyridine (4VP). The corresponding copolymers can be post functionalized by using amine group in 4VP unit to get polymers bearing various properties. Elemental sulfur was heated up to 160 degrees C and 4VP was added slowly to a clear yellowish orange colored liquid at this temperature. The reaction mixture was vitrified to form a reddish-brown polymeric material at 180 degrees C in 1 h. The products were characterized by using FTIR, NMR, and Raman spectroscopic techniques. Poly(S-r-4VP) copolymers are soluble in common solvents like dichloromethane, chloroform and tetrahydrofuran. Weight-average molecular weights of poly(S-r-4VP) copolymers with different wt% 4VP were measured by using gel permeation chromatography technique. The polysulfide copolymers with different wt% 4VP have high weight-average molecular weights with polydispersity indeces (PDI) in a range from 1.88 to 4.06 measured by gel permeation chromatography. Post functionalization of the copolymer with 50 wt% 4VP as an example was performed successfully by using alkyl bromide to get N-alkyl quaternized 4VP in polymer backbone.Article Citation - WoS: 79Citation - Scopus: 84Methylene Blue Photocatalytic Degradation Under Visible Light Irradiation on Copper Phthalocyanine-Sensitized Tio2 Nanopowders(Elsevier Science Bv, 2017) Cabir, Beyza; Yurderi, Mehmet; Caner, Nurdan; Agirtas, Mehmet Salih; Zahmakiran, Mehmet; Kaya, MuratDescribed herein is a new photocatalytic material that shows remarkable catalytic performance in terms of activity and reusability in the photocatalytic degradation of methylene blue (MB) in water. The new catalyst system comprised of copper phthalocyanine modified titanium(IV) oxide (TiO2) nanopowders (CuPc-TiO2\) was prepared by the wet chemical impregnation method to improve the photocatalytic activity of TiO2 and characterized by the combination of various spectroscopic tools including ICP-OES, P-XRD, DR/UV-Vis, FTIR, FE-SEM, SEM-EDX, BFTEM, HRTEM and N-2-adsorption-desorption techniques. The photocatalytic performance of the resulting CuPc-TiO2 in terms of activity and stability was evaluated by the photocatalytic degradation of MB in aqueous solution under mild conditions. Our results revealed that CuPc-TiO2 photocatalyst displayed remarkable activity (TOF = 3.73 mol MB/(mol CuPc + mol TiO2) x h) in the complete (100%) photocatalytic degradation of MB under visible light irradiation (150 W). Moreover, CuPc-TiO2 photocatalyst showed excellent stability against to sintering and clumping throughout the reusability experiments and it retained >80% of its initial activity even at 5th reuse, which makes it reusable photocatalyst in the photocatalytic degradation of MB. (C) 2017 Elsevier B.V. All rights reserved.Article Citation - WoS: 25Citation - Scopus: 28Palladium(0) Nanoparticles Supported on Hydroxyapatite Nanospheres: Active, Long-Lived, and Reusable Nanocatalyst for Hydrogen Generation From the Dehydrogenation of Aqueous Ammonia-Borane Solution(Springer, 2014) Karatas, Yasar; Yurderi, Mehmet; Gulcan, Mehmet; Zahmakiran, Mehmet; Kaya, MuratAmong the solidmaterials considered in the chemical hydrogen storage, ammonia-borane (NH3-BH3) appears to be one of the promising candidates as it can release hydrogen throughout hydrolysis in the presence of suitable catalyst under mild conditions. Herein we report, for the first time, the preparation and characterization of palladium(0) nanoparticles supported on nanohydroxyapatite and their catalytic use in the hydrolysis of ammonia-borane under air at room temperature. These new palladium(0) nanoparticles were generated in situ during the catalytic hydrolysis of ammonia-borane starting with palladium(II) immobilized nanohydroxyapatite. The preliminary characterization of the palladium(0) nanoparticles supported on nanohydroxyapatite was done by the combination of complimentary techniques, which reveals that the formation of well-dispersed Pd(0)NPs nanoparticles (1.41 +/- 0.52 nm) on the surface of hydroxyapatite nanospheres (60-150 nm). The resulting palladium nanocatalyst achieves hydrogen generation from the hydrolysis of ammonia-borane with an initial turnover frequency value (TOF) of 11 mol H-2 mol(-1) Pd x min at room temperature under air. In addition to their high activity, the catalytic lifetime experiment showed that they can also act as a long-lived heterogeneous catalyst for this reaction (TTON = 14,200 mol H-2 mol(-1) Pd) at room temperature under air. More importantly, nanohydroxyapatite- supported palladium(0) nanoparticles were found to be highly stable against to leaching and sintering throughout the catalytic runs that make them isolable, bottleable, and reusable heterogeneous catalyst for the hydrolysis of ammonia-borane.Article Citation - WoS: 35Citation - Scopus: 37Hydroxyapatite-Nanosphere Supported Ruthenium(0) Nanoparticle Catalyst for Hydrogen Generation From Ammonia-Borane Solution: Kinetic Studies for Nanoparticle Formation and Hydrogen Evolution(Royal Soc Chemistry, 2014) Durak, Halil; Gulcan, Mehmet; Zahmakiran, Mehmet; Ozkar, Saim; Kaya, MuratThe development of readily prepared effective heterogeneous catalysts for hydrogen generation from ammonia-borane (AB; NH3BH3) solution under mild conditions still remains a challenge in the field of "hydrogen economy". In this study, we report our finding of an in situ generated, highly active ruthenium nanocatalyst for the dehydrogenation of ammonia-borane in water at room temperature. The new catalyst system consists of ruthenium(0) nanoparticles supported on nanohydroxyapatite (RuNPs@nano-HAp), and can be reproducibly prepared under in situ conditions from the ammonia-borane reduction of Ru3+ ions exchanged into nanohydroxyapatite (Ru3+@nano-HAp) during the hydrolytic dehydrogenation of ammonia-borane at 25 +/- 0.1 degrees C. Nanohydroxyapatite-supported ruthenium(0) nanoparticles were characterized by a combination of advanced analytical techniques. The sum of their results shows the formation of well-dispersed ruthenium(0) nanoparticles with a mean diameter of 2.6 +/- 0.6 nm on the surface of the nanospheres of hydroxyapatite by keeping the host matrix intact. The resulting RuNPs@nano-HAp are highly active catalyst in the hydrolytic dehydrogenation of ammonia-borane with an initial TOF value of 205 min(-1) by generating 3.0 equiv. of H-2 per mole of ammonia-borane at 25 +/- 0.1 degrees C. Moreover, they are sufficiently stable to be isolated and bottled as solid materials, which can be reused as active catalyst under the identical conditions of first run. The work reported here also includes the following results: (i) monitoring the formation kinetics of the in situ generated RuNPs@nano-HAp by hydrogen generation from the hydrolytic dehydrogenation of ammonia-borane as the reporter reaction. The sigmoidal kinetics of catalyst formation and concomitant dehydrogenation fits well to the two-step, slow nucleation, followed by autocatalytic surface growth mechanism, P -> Q (rate constant k(1)) and P + Q -> 2Q (rate constant k(2)), in which P is Ru3+@nano-HAp and Q is the growing, catalytically active RuNPs@nano-HAp; (ii) the compilation of kinetic data for the RuNPs@nano-HAp catalyzed hydrolytic dehydrogenation of ammonia-borane depending on the temperature and catalyst concentration to determine the dependency of reaction rate on catalyst concentration and activation parameters (E-a, Delta H-#, and Delta S-#) of the reaction.Article Citation - WoS: 80Citation - Scopus: 82Amine Grafted Silica Supported Craupd Alloy Nanoparticles: Superb Heterogeneous Catalysts for the Room Temperature Dehydrogenation of Formic Acid(Royal Soc Chemistry, 2015) Yurderi, Mehmet; Bulut, Ahmet; Caner, Nurdan; Celebi, Metin; Kaya, Murat; Zahmakiran, MehmetHerein we show that a previously unappreciated combination of CrAuPd alloy nanoparticles and amine-grafted silica support facilitates the liberation of CO-free H-2 from dehydrogenation of formic acid with record activity in the absence of any additives at room temperature. Furthermore, their excellent catalytic stability makes them isolable and reusable heterogeneous catalysts in the formic acid dehydrogenation.Article Citation - WoS: 19Citation - Scopus: 20Synthesis, Characterization, and Enhanced Formic Acid Electrooxidation Activity of Carbon Supported Mnox Promoted Pd Nanoparticles(Elsevier, 2018) Bulut, Ahmet; Yurderi, Mehmet; Alal, Orhan; Kivrak, Hilal; Kaya, Murat; Zahmakiran, MehmetFormic acid (HCOOH) is one of the promising fuels for direct liquid fed fuel cells. However, CO poisoning is a major challenge for the development of effective catalytic system for formic acid electrooxidation (FAEO). Herein, a novel CO-resistive activated carbon supported Pd-MnOx bimetallic catalyst (Pd-MnOx/C) was presented for FAEO. Pd-MnOx/C catalyst was prepared via simple and reproducible surfactant-free deposition-reduction technique. The characterization of this novel Pd-MnOx/C catalyst was performed by inductively coupled plasma-optical emission spectroscopy (ICP-OES), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), bright field transmission electron microscopy (BFTEM), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), and scanning transmission electron microscope-energy dispersive X-ray spectroscopy (STEM-EDX). The characterization results revealed that Pd and MnOx nanoparticles (NPs) were well dispersed and separately nucleated with a mean diameter of 2.9 nm on the surface of active carbon. FAEO studies were performed on both Pd-MnOx/C and Pd/C catalysts to comprehend the effect of separately formed MnOx on the electrocatalytic activity of Pd NPs. The electrochemical measurements were carried out by using Cyclic Voltammetry (CV) and Chronoamperometry (CA), CO-Strriping Voltammetry, Lineer Sweep Voltammetry (LSV), Electrochemical impedance spectroscopy (EIS) techniques. Electrochemical results revealed that FAEO was activated by the addition of MnOx. Pd-0.6-Mn-0.4 exhibited the optimum catalytic activity with 1.05 A/mg Pd current density. The sum of their results clearly points that the existence of MnOx NPs enhances the electrocatalytic activity of Pd NPs by increasing their CO-resistivity and durability throughout the FAEO. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.Article Citation - WoS: 37Citation - Scopus: 34Preparation of Silica Coated Cobalt Ferrite Magnetic Nanoparticles for the Purification of Histidine-Tagged Proteins(Pergamon-elsevier Science Ltd, 2015) Aygar, Gulfem; Kaya, Murat; Ozkan, Necati; Kocabiyik, Semra; Volkan, MurvetSurface modified cobalt ferrite (CoFe2O4) nanoparticles containing Ni-NTA affinity group were synthesized and used for the separation of histidine tag proteins from the complex matrices through the use of imidazole side chains of histidine molecules. Firstly, CoFe2O4 nanoparticles with a narrow size distribution were prepared in an aqueous solution using the controlled co-precipitation method. In order to obtain small CoFe2O4 agglomerates, oleic acid and sodium chloride were used as dispersants. The CoFe2O4 particles were coated with silica and subsequently the surface of these silica coated particles (SiO2-CoFe2O4) was modified by amine (NH2) groups in order to add further functional groups on the silica shell. Then, carboxyl (-COOH) functional groups were added to the SiO2-CoFe2O4 magnetic nanoparticles through the NH2 groups. After that N alpha,N alpha-Bis(carboxymethyl)-L-lysine hydrate (NTA) was attached to carboxyl ends of the structure. Finally, the surface modified nanoparticles were labeled with nickel (Ni) (II) ions. Furthermore, the modified SiO2-CoFe2O4 magnetic nanoparticles were utilized as a new system that allows purification of the N-terminal His-tagged recombinant small heat shock protein, Tpv-sHSP 14.3. (C) 2015 Elsevier Ltd. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 14Thermally Highly Stable Polyhedral Oligomeric Silsesquioxane (poss)-Sulfur Based Hybrid Inorganic/Organic Polymers: Synthesis, Characterization and Removal of Mercury Ion(Royal Soc Chemistry, 2022) Berk, Hasan; Kaya, Murat; Cihaner, AtillaElemental sulfur was copolymerized with octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) cages in diglyme solution via the inverse vulcanization method and characterized using NMR and FTIR spectroscopic techniques. The polysulfur copolymer called poly(sulfur-random-octavinyl polyhedral oligomeric silsesquioxane) (poly(S-r-OV-POSS)) was cured successfully sequentially at 170, 200 and 230 degrees C without changing the structure of the POSS cages in the polymer backbone. Highly crosslinked poly(S-r-OV-POSS) polymer cured at 200 and 230 degrees C exhibited high thermal stability at high temperatures; the loss of the samples was only 10% weight at 400 degrees C and 27% at 800 degrees C. Finally, the feasibility of poly(S-r-OV-POSS) as an adsorbent for the removal of Hg(ii) ions, as an example of a toxic heavy metal, from an aqueous solution was investigated. Optimization of the pH of the solution and contact time was performed and almost all Hg(ii) ions were collected from the aqueous solution at pH = 7 in 1 h (99% adsorption).
