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Article Citation - WoS: 22Citation - Scopus: 23Complete 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, MehmetHydrazine 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.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 Citation - WoS: 150Citation - Scopus: 152Pd-mnox< Nanoparticles Dispersed on Amine-Grafted Silica: Highly Efficient Nanocatalyst for Hydrogen Production From Additive-Free Dehydrogenation of Formic Acid Under Mild Conditions(Elsevier Science Bv, 2015) Bulut, Ahmet; Yurderi, Mehmet; Karatas, Yasar; Zahmakiran, Mehmet; Kivrak, Hilal; Gulcan, Mehmet; Kaya, MuratHerein we report the development of a new highly active, selective and reusable nanocatalyst for additive-free dehydrogenation of formic acid (HCOOH), which has great potential as a safe and convenient hydrogen carrier for fuel cells, under mild conditions. The new catalyst system consisting of bimetallic Pd-MnOx nanoparticles supported on aminopropyl functionalized silica (Pd-MnOx/SiO2-NH2) was simply and reproducibly prepared by deposition-reduction technique in water at room temperature. The characterization of Pd-mnO(x)/SiO2-NH2 catalyst was done by the combination of multipronged techniques, which reveals that the existence of highly crystalline individually nucleated Pd(0) and MnOx nanoparticles (d(mean) = 4.6 +/- 1.2 nm) on the surface of aminopropyl functionalized silica. These supported Pd-MnOx nanoparticles can catalyze the additive-free dehydrogenation of formic acid with record activity (TOF = 1300 h(-1)) at high selectivity (>99%) and conversion (>99%) under mild conditions (at 50 degrees C and under air). Moreover, easy recovery plus high durability of these supported Pd-MnOx nanoparticles make them a reusable heterogeneous catalyst in the additive-free dehydrogenation of formic acid. (C) 2014 Elsevier B.V. All rights reserved.Article Citation - WoS: 125Citation - Scopus: 130Pdau-mnox< Nanoparticles Supported on Amine-Functionalized Sio2 for the Room Temperature Dehydrogenation of Formic Acid in the Absence of Additives(Elsevier Science Bv, 2016) Karatas, Yasar; Bulut, Ahmet; Yurderi, Mehmet; Ertas, Ilknur Efecan; Alal, Orhan; Gulcan, Mehmet; Zahmakiran, MehmetFormic acid (HCOOH) has recently been suggested as a promising hydrogen carrier for fuel cell applications. However efficient hydrogen production through the decomposition of formic acid in the absence of additives under mild thermodynamic conditions constitutes a major challenge because of the ease poisoning of active metals with CO formed as intermediate during formic acid decomposition. Recently, we have reported (App. Catal. B: Env. 164 (2015) 324) our discovery that the separately nucleated MnOx nanoparticles act as CO-sponge around catalytically active Pd nanoparticles exist on the same support and enhances both the activity and CO-resistivity of Pd nanoparticles. Using this important finding, herein, we present a new catalyst system consists of the physical mixture of PdAu alloy and MnOx nanoparticles supported on amine-grafted silica (PdAu-MnOx/N-SiO2) for the room temperature dehydrogenation of formic acid in the absence of any additives. PdAu-MnOx/N-SiO2 catalyst was simply prepared by deposition-reduction technique in water at room temperature with high reproducibility and characterized by the combination of various spectroscopic tools including ICP-OES, P-XRD, DR/UV-vis, XPS, BFTEM, STEM-EDX, STEM-line analysis and CO-stripping voltammetry techniques. The sum of their results shows that the formation of physical mixture of PdAu alloy and MnOx (dmean=2.2 nm) nanoparticles on the surface of support material. This new catalytic material facilitates the hydrogen liberation through the additive-free formic acid dehydrogenation at room temperature with previously unprecedented activity (TOF=785 mol H-2 mol catalyst(-1) h(-1)), converging to that of the existing state of the art homogenous catalysts. This new superior catalytic system enables facile catalyst recovery and very high stability against agglomeration, leaching and CO poisoning, which make it highly reusable catalyst (retains >92% activity and 85% conversion at the 5th catalytic reuse) in the additive-free formic acid dehydrogenation at room temperature. (C) 2015 Elsevier B.V. All rights reserved.Correction Citation - WoS: 1Citation - Scopus: 2Supported Copper-Copper Oxide Nanoparticles as Active, Stable and Low-Cost Catalyst in the Methanolysis of Ammonia-Borane for Chemical Hydrogen Storage (vol 165, Pg 169, 2015)(Elsevier, 2016) Yurderi, Mehmet; Bulut, Ahmet; Ertas, Ilknur Efecan; Zahmakiran, Mehmet; Kaya, Murat[No Abstract Available]Article Citation - WoS: 141Citation - Scopus: 147Carbon Dispersed Copper-Cobalt Alloy Nanoparticles: a Cost-Effective Heterogeneous Catalyst With Exceptional Performance in the Hydrolytic Dehydrogenation of Ammonia-Borane(Elsevier, 2016) Bulut, Ahmet; Yurderi, Mehmet; Ertas, Ilknur Efecan; Celebi, Metin; Kaya, Murat; Zahmakiran, MehmetHerein, we report the development of a new and cost-effective nanocatalyst for the hydrolytic dehydrogenation of ammonia-borane (NH3BH3), which is considered to be one of the most promising solid hydrogen carriers due to its high gravimetric hydrogen storage capacity (19.6 wt%) and low molecular weight. The new catalyst system consisting of bimetallic copper-cobalt alloy nanoparticles supported on activated carbon was simply and reproducibly prepared by surfactant-free deposition-reduction technique at room temperature. The characterization of this new catalytic material was done by the combination of multi-pronged techniques including ICP-MS, XRD, XPS, BFTEM, HR-TEM, STEM and HAADF-STEM-line analysis. The sum of their results revealed that the formation of copper-cobalt alloy nanoparticles (d(mean) =1.8 nm) on the surface of activated carbon (CuCo/C). These new carbon supported copper-cobalt alloy nanoparticles act as highly active catalyst in the hydrolytic dehydrogenation of ammonia-borane, providing an initial turnover frequency of TOF = 2700 h(-1) at 298 K, which is not only higher than all the non-noble metal catalysts but also higher than the majority of the noble metal based homogeneous and heterogeneous catalysts employed in the same reaction. More importantly, easy recovery and high durability of these supported CuCo nanoparticles make CuCo/C recyclable heterogeneous catalyst for the hydrolytic dehydrogenation of ammonia-borane. They retain almost their inherent activity even at 10th catalytic reuse in the hydrolytic dehydrogenation of ammonia-borane at 298K. (C) 2015 Elsevier B.V. All rights reserved.Article Citation - WoS: 203Citation - Scopus: 212Palladium Nanoparticles Supported on Amine-Functionalized Sio2 for the Catalytic Hexavalent Chromium Reduction(Elsevier Science Bv, 2016) Celebi, Metin; Yurderi, Mehmet; Bulut, Ahrnet; Kaya, Murat; Zahmakiran, MehmetHexavalent chromium (Cr(VI)) is commonly identified acutely toxic, a proven mutagen and carcinogen heavy metal pollutant in the aquatic environment, whereas Cr(III) is believed to be an essential element. In the present study, we show that palladium(0) nanoparticles supported on 3-aminopropyltriethoxysilane (APTS) functionalized silica (Pd@SiO2-NH2) effectively catalyze the reduction of Cr(VI) to Cr(III) by using formic acid (HCOOH) as reducing agent under mild conditions (at room temperature under air). Pd@SiO2-NH2 catalyst was reproducibly prepared by deposition-reduction technique and characterized by the combination of various spectroscopic tools including ICP-OES, P-XRD, DR/UV-vis, XPS, BFTEM, HRTEM and TEM-EDX techniques. The sum of their results is indicative of the formation of well-dispersed palladium(0) nanoparticles (d(mean) = 3.7 nm) on the surface of APTS-functionalized SiO2. The catalytic performance of the resulting palladium(0) nanoparticles in terms of activity and stability was evaluated by the catalytic reduction of Cr(VI) to Cr(III) in aqueous solution in the presence of formic acid as a reducing agent. Our results reveal that Pd@SiO2-NH2 catalyst displays unprecedented activity (TOF = 258 mol Cr2O72-/mol Pd min) and reusability (<85% at 5th reuse) for the reduction of Cr(VI) to Cr(III) at room temperature. The present study reported here also includes the compilation of wealthy kinetic data for Pd@SiO2-NH2 catalyzed the reduction of Cr(VI) to Cr(III) in aqueous formic acid (HCOOH)-sodium formate (HCOONa) solution depending on substrate [Cr2O72-], catalyst [Pd@SiO2-NH2], surface grafted amine [APTS], formic acid [HCOOH], sodium formate [HCOONa] concentrations, temperature and type of support material (Al2O3, C, unmodified SiO2) to understand the nature of the catalytic reaction and determine the rate expression and activation parameters. (C) 2015 Elsevier B.V. All rights reserved.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: 24Citation - 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: 128Mnox< Pdag Alloy Nanoparticles for the Additive-Free Dehydrogenation of Formic Acid at Room Temperature(Amer Chemical Soc, 2015) Bulut, Ahmet; Yurderi, Mehmet; Karatas, Yasar; Say, Zafer; Kivrak, Hilal; Kaya, Murat; Zahmakiran, MehmetFormic acid (HCOOH) has a great potential as a safe and a convenient hydrogen carrier for fuel cell applications. However, efficient and CO-free hydrogen production through the decomposition of formic acid at low temperatures (<363 K) in the absence of additives constitutes a major challenge. Herein, we present a new heterogeneous catalyst system composed of bimetallic PdAg alloy and MnOx nanoparticles supported on amine-grafted silica facilitating the liberation of hydrogen at room temperature through the dehydrogenation of formic acid in the absence of any additives with remarkable activity (330 mol H-2 center dot mol catalyst(-1)center dot h(-1)) and selectivity (>99%) at complete conversion (>99%). Moreover this new catalytic system enables facile catalyst recovery and very high stability against agglomeration, leaching, and CO poisoning. Through a comprehensive set of structural and functional characterization experiments, mechanistic origins of the unusually high catalytic activity, selectivity, and stability of this unique catalytic system are elucidated. Current heterogeneous catalytic architecture presents itself as an excellent contender for clean hydrogen production via room-temperature additive-free dehydrogenation of formic acid for on-board hydrogen fuel cell applications.
