Browsing by Author "Rakap, Murat"

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Catalytic Hydrolysis of Hydrazine Borane To Release Hydrogen by Cobalt-Ruthenium Nanoclusters
(Pergamon-elsevier Science Ltd, 2020) Rakap, Murat
The first-time synthesis and use of poly (N-vinyl-2-pyrrolidone)-stabilized cobaltruthenium nanoclusters (4.1 +/- 1.2 nm) to produce pure hydrogen gas from hydrazine borane via hydrolysis is reported here. The cobalt-ruthenium nanoclusters are synthesized by co-reduction of water-soluble suitable cobalt and ruthenium salts in ethanol/water mixture by refluxing. They are characterized by advanced analytical techniques of transmission electron microscopy and UV-Vis and X-ray photoelectron spectroscopies. They are very stable and durable nanocatalysts found to be highly effective towards hydrogen evolution from hydrolysis of hydrazine borane at mild conditions. They provide 90 min(-1) of average turnover frequency value and 56.2 kJmol(-1) of activation energy for this catalytic hydrolysis of hydrazine borane. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Eco-Friendly Synthesis of Carboxymethyl Cellulose-Stabilized Ru0.57co0.43 Nanoclusters as Extremely Efficient and Durable Catalysts for Hydrolytic Dehydrogenation of Methylamine Borane
(Amer Chemical Soc, 2020) Abay, Bayram; Rakap, Murat
Herein, we report the first ever eco-friendly and easy synthesis of carboxymethyl cellulose-stabilized RuCo nanoclusters (Ru0.57Co0.43@CMC) and their use as highly efficient and durable catalysts to produce hydrogen from hydrolytic dehydrogenation of methylamine borane (MeAB). Ru0.57Co0.43@CMC nanoclusters are easily synthesized from synchronous chemical reduction of suitable water-soluble cobalt and ruthenium salts by sodium borohydride. They are identified by some advanced methods including ultraviolet-visible spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. All related kinetic studies show that Ru0.57Co0.43@CMC nanoclusters are extremely efficient, relatively cost-saver, and durable catalysts in hydrolytic dehydrogenation of MeAB at very low temperatures. They provided the highest ever initial turnover frequency value of 327.1 min(-1) and also the apparent activation energy of 49.7 kJ/mol for the hydrolytic dehydrogenation of MeAB.
Hidrazin Boranın Hidrolizi İçin Ucuz ve Etkin Katalizörlerin Geliştirilmesi
(2016) Rakap, Murat
Bu çalısmada; poli(N-vinil-2-pirrolidon) ile kararlılastırılmıs CoNiM (M: Palladyum, Rutenyum, Rodyum) trimetalik nanokümeleri, uygun metal tuzlarının sulu çözeltide kararlılastırıcı olarak PVP varlıgında sodyum borhidrür ile indirgenmesi sonucu sentezlendiler ve hidrazin boranın hidrolizinde etkin katalizörler olarak kullanıldılar. Sentezlenen katalizörler, geçirgenli elektron mikroskopisi (TEM), UV-görünür bölge spektroskopisi (UV-Vis) ve X-ısınları fotoelektron spektroskopisi (XPS) ile tanımlandı. CoNiPd@PVP, CoNiRu@PVP ve CoNiRh@PVP nanokümelerinin tanecik boyutları sırasıyla 4.5±1.1, 4.2±1.2 ve 4.7±1.3 nm olarak belirlendi. CoNiPd@PVP, CoNiRu@PVP ve CoNiRh@PVP nanokümelerinin hidrazin boranın hidrolizindeki ortalama çevrim frekansları sırasıyla 115 dak-1, 300 dak-1 ve 400 dak-1?dir. CoNiPd@PVP, CoNiRu@PVP ve CoNiRh@PVP nanokümelerinin hidrazin boranın hidrolizindeki aktivasyon enerjileri sırasıyla 55.9, 55.5 ve 62.3 kJ/mol?dür.
The Highest Catalytic Activity in the Hydrolysis of Ammonia Borane by Poly(n-Vinyl Palladium-Rhodium Nanoparticles for Hydrogen Generation
(Elsevier Science Bv, 2015) Rakap, Murat
The use of poly(N-vinyl-2-pyrrolidone)-protected palladium-rhodium nanoparticles (2.5 +/- 1.1 nm) as highly efficient catalysts providing a record catalytic activity in the hydrolysis of ammonia borane for hydrogen generation is reported. They are prepared by co-reduction of palladium and rhodium metal ions in ethanol/water mixture by an alcohol reduction method and characterized by TEM-EDX analysis, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. They are recyclable and highly efficient catalysts for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing record average turnover frequency (1333 mol H-2 (mol cat)(-1) min(-1)), maximum hydrogen generation rate (36,414 L H-2 min(-1) (mol cat)(-1)), and total turnovers (171,000). Poly(N-vinyl-2-pyrrolidone)-protected palladium-rhodium nanoparticles also provide activation energy of 46.1 +/- 2 kJ/mol for the hydrolysis of ammonia borane. (C) 2014 Elsevier B.V. All rights reserved.
Hydrogen Generation From Ammonia Borane by Niru Nanoparticles Catalysts
(Taylor & Francis inc, 2021) Abay, Bayram; Rakap, Murat
The preparation, characterization and catalytic test of alloy type poly(N-vinyl-2-pyrrolidone)-protected nickel-ruthenium nanoparticles (3.8 +/- 1.6 nm) (Ni-Ru@PVP) to liberate hydrogen from ammonia borane via hydrolysis have been reported in the present study. Ni-Ru@PVP nanoparticles have easily been synthesized by simultaneous reduction of suitable water-soluble nickel and ruthenium salts in the mixture of water/ethanol by a modified method of alcohol reduction with PVP as both reducing agent and stabilizer. They have been characterized by ultraviolet-visible spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. They have been detected to be highly efficient and durable catalysts to liberate hydrogen from ammonia borane via hydrolysis under ambient conditions. Among prepared catalysts, Ni0.5Ru0.5@PVP nanoparticles provided mean turnover frequency (TOF) of 300 min(-1)and activation energy of 46.8 +/- 1.2 kJ mol(-1)in this hydrolysis reaction.
Hydrogen Generation From Hydrolysis of Ammonia Borane in the Presence of Highly Efficient Poly(n-Vinyl Platinum-Ruthenium Nanoparticles
(Elsevier, 2014) Rakap, Murat
Herein, the employment of PVP-protected Pt-Ru bimetallic nanoparticles (3.2 +/- 1.4 nm) as highly efficient catalysts in the hydrolysis of ammonia borane for hydrogen generation is reported. They were prepared by co-reduction of two metal ions in ethanol/water mixture by an alcohol reduction method and characterized by TEM-EDX analysis, UV-vis spectroscopy, and X-ray photoelectron spectroscopy. They are recyclable and highly active for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing a record numbers of average TOP value (308 mol H-2 MOl(cat)(-1) min(-1)) and maximum hydrogen generation rate (9884 L H-2 min(-1) (mol(cat))(-1)) for ammonia borane. PVP-protected Pt-Ru bimetallic nanoparticles provide activation energy of 56.3 +/- 2 kJ mol(-1) for the hydrolysis of ammonia borane. (C) 2014 Elsevier B.V. All rights reserved.
Hydrogen Generation From Hydrolytic Dehydrogenation of Hydrazine Borane by Poly(n-Vinyl Palladium Nanoparticles
(Elsevier Science Bv, 2015) Tunc, Nihat; Abay, Bayram; Rakap, Murat
Poly(N-vinyl-2-pyrrolidone)-stabilized palladium nanoparticles (3.5 +/- 1.0 nm) are efficient catalysts in the hydrolytic dehydrogenation of hydrazine borane to give hydrogen gas. The catalyst, prepared by reduction of palladium metal ion in ethanol/water mixture by an alcohol reduction method, is durable and efficient catalysts for hydrogen generation from the hydrolytic dehydrogenation of hydrazine borane even at very low concentrations and temperature, providing an average turnover frequency of 42.9 min(-1) with an activation energy of 54.5 +/- 2 kJ mol(-1) for the hydrolytic dehydrogenation of hydrazine borane. (C) 2015 Elsevier B.V. All rights reserved.
Hydrogen Generation From the Hydrolytic Dehydrogenation of Ammonia Borane Using Electrolessly Deposited Cobalt-Phosphorus as Reusable and Cost-Effective Catalyst
(Elsevier, 2014) Rakap, Murat
The development of catalytically active, low-cost, and reusable catalysts is very vital for on-demand hydrogen generation systems for practical onboard applications. Titanium dioxide supported-cobalt phosphorus (Co-P/TiO2) catalyst prepared by electroless deposition has been shown to effectively promote the release of hydrogen from the hydrolytic dehydrogenation of ammonia borane. The catalyst is very stable to be isolated as solid material and characterized by XRD, SEM-EDX, and XPS. It is redispersible and reusable as an active catalyst in the hydrolytic dehydrogenation of AB. The activation energy (Ea) for the hydrolytic dehydrogenation of ammonia borane catalyzed by Co-P/TiO2 catalyst is 48.1 +/- 2 kJ mol(-1). Maximum hydrogen generation rate in the hydrolytic dehydrogenation of ammonia borane catalyzed by Co-P/TiO2 catalyst is 2002 mL H-2 min(-1) (g catalyst)(-1). (C) 2014 Elsevier B.V. All rights reserved.
Hydrogen Liberation From Ethylenediamine Bisborane Hydrolysis by Platinum Nanoparticles
(Pergamon-elsevier Science Ltd, 2022) Abay, Bayram; Rakap, Murat
The synthesis and characterization of poly (N-vinyl-2-pyrrolidone)-protected platinum (Pt/ PVP) nanoparticles with their employment as highly effective catalysts to liberate hydrogen from hydrolysis of ethylenediamine bisborane (EDAB) is reported here. The nanoparticles are easily synthesized from the reduction of platinum cations in ethanol/water mixture under refluxing. They remain stable for months without any sign of precipitation. They are characterized by fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Pt/PVP nanoparticles provide the greatest TOF value (166.7 min(-1)) reported so far for the hydrolysis of EDAB. Their activation energy is 81.9 kJ mol(-1) in the same reaction. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Hydrolysis of Ammonia Borane and Hydrazine Borane by Poly(n-Vinyl Copd Nanoparticles for Chemical Hydrogen Storage
(Tubitak Scientific & Technological Research Council Turkey, 2017) Rakap, Murat; Abay, Bayram; Tunc, Nihat
For the first time the synthesis of poly(N-vinyl-2-pyrrolidone)-stabilized cobalt-palladium nanoparticles by an easy method, their characterization, and their use as active catalysts for hydrogen release from hydrolysis of ammonia borane and hydrazine borane is reported here. The catalyst is prepared by simultaneous reduction of suitable cobalt and palladium ions by sodium borohydride in the presence of poly(N-vinyl-2-pyrrolidone) as a stabilizer. They are characterized by UV-Vis spectroscopy, TEM analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. They provide average turnover frequencies of 30 min(-1) and 45 min(-1) in the hydrolysis of ammonia borane and hydrazine borane. They also provide activation energies of 48.6 +/- 2 and 50.6 +/- 2 kJ mol(-1) in the hydrolysis of ammonia borane and hydrazine borane.
Hydrolysis of Sodium Borohydride and Ammonia Borane for Hydrogen Generation Using Highly Efficient Poly(n-Vinyl Ru-Pd Nanoparticles as Catalysts
(Taylor & Francis inc, 2015) Rakap, Murat
The catalytic use of highly efficient poly(N-vinyl-2-pyrrolidone)-stabilized Ru-Pd nanoparticles (3.2 +/- 1.0 nm) in the hydrolysis of sodium borohydride and ammonia borane is reported. These were prepared by the co-reduction of two metal ions in ethanol/water mixture by the alcohol reduction method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy. These are recyclable and highly active for hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane even at very low concentrations and temperature, providing a record number of average turnover frequency values (762 mol H-2/mol cat.min(-1) and 308 mol H-2/mol cat.min(-1)) and maximum hydrogen generation rates (22,889 L H-2 min(-1) (mol cat)(-1) and 9364 L H-2 min(-1) (mol cat)(-1)) for sodium borohydride and ammonia borane, respectively. Poly(N-vinyl-2-pyrrolidone)-stabilized Ru-Pd nanoparticles provide activation energies of 52.4 +/- 2 and 54.5 +/- 2 kJ/mol for the hydrolysis of sodium borohydride and ammonia borane, respectively.
Instant Hydrogen Release From Ethylenediamine Bisborane by Highly Efficacious Rh Catalysts Via Hydrolysis
(Elsevier, 2025) Tunc, Nihat; Rakap, Murat
This current study reports preparation, characterization, and first-time catalytic employment of rhodium nanoparticles (2.6 nm) stabilized by polyvinylpyrrolidone (PVP) in hydrolysis of ethylenediamine bisborane (EDAB) to release hydrogen gas needed for fuel cells. Rhodium nanoparticles stabilized by PVP are characterized by advanced analytical techniques like fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). They are identified as the most effective catalyst up to date for hydrogen gas evolution from EDAB hydrolysis with the highest turnover frequency (TOF) value of 1928.6 min- 1. They also provide 4821 total turnovers in the same hydrolysis reaction. Their energy (Ea), enthalpy (Delta H#), and entropy (Delta S#) of activation in EDAB hydrolysis are determined to be 65.5 kJmol-1, 63.1 kJmol-1, and -49.3 Jmol-1K-1.
Nanoceria-Supported Ru-Based Nanoparticles as Highly Efficient Catalysts for Hydrolysis of Ethane 1,2-Diamine Borane
(Wiley-v C H verlag Gmbh, 2022) Tunc, Nihat; Rakap, Murat
Here, the first ever preparation of some series of nanoceria-supported Ru-based nanoparticles with different compositions (RuxM100-x@NC, M: Co, Ni, Pd) and their use as highly active catalysts to liberate hydrogen gas from hydrolysis of ethane 1,2-diamine borane (EDAB) is reported. For the preparation of totally fifteen RuxM100-x@NC nanoparticles with different compositions, the related metal cations are first supported on nanoceria surfaces by wet impregnation method in aqueous solution. Then, Ru3+-M2+-exchanged nanoceria samples are synchronously reduced during hydrolysis reaction of EDAB to form corresponding RuxM100x@NC nanoparticles meanwhile the formed nanoparticles catalyze the same reaction. RuxM100x@NC nanoparticles are identified by inductively coupled plasma-optical emission spectroscopy (ICP-OES), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and BET surface area techniques. They provide quiet high catalytic activities in the hydrolysis reaction of EDAB. Among them, Ru20Pd80@NC nanoparticles are by far the best one up to date with a TOF value of 608.49 min(-1) at 25 degrees C.
Nickel-Rhodium Nanoparticles as Active and Durable Catalysts for Hydrogen Liberation
(Taylor & Francis inc, 2020) Tunc, Nihat; Rakap, Murat
Herein, synthesis, characterization, and catalytic utilization of rather efficient carboxymethyl cellulose-stabilized nickel-rhodium nanoparticles (4.5 +/- 0.7 nm) in hydrogen liberation from ammonia borane and hydrazine borane by hydrolysis are reported. The catalysts are prepared by simultaneous reduction of appropriate nickel and rhodium salts in aqueous solution by sodium borohydride by using carboxymethyl cellulose as a stabilizer. Transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy are used to characterize the catalysts. The catalysts are highly durable and effective to liberate hydrogen from ammonia borane and hydrazine borane in aqueous solution at lower concentrations and temperature. Among prepared catalysts, Ni0.50Rh0.50@CMC provides 200 min(-1) and 188 min(-1) of average turnover frequencies and 46.8 +/- 2 kJ/mol and 60.3 +/- 2 kJ/mol of activation energies for ammonia borane and hydrazine borane hydrolysis reactions, respectively.
Poly(n-Vinyl Palladium-Platinum Nanoparticles-Catalyzed Hydrolysis of Ammonia Borane for Hydrogen Generation
(Elsevier Science Bv, 2015) Rakap, Murat
The catalytic use of highly efficient poly(N-vinyl-2-pyrrolidone)-stabilized palladium platinum nanoparticles (4.2 +/- 1.9 nm) in the hydrolysis of ammonia-borane is reported. The catalyst is prepared by co-reduction of two metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy,.X-ray photoelectron spectroscopy and UV-Vis spectroscopy. They are recyclable and highly active for hydrogen generation from the hydrolysis of ammonia-borane even at very low concentrations and temperature, providing a record numbers of average turnover frequency value (125 mol H-2/mol cat.min(-1)) and maximum hydrogen generation rate (3468 L H-2 min(-1) (mol cat)(-1)). They also provide activation energy of 51.7 +/- 2 kJ/mol for the hydrolysis of ammonia borane. (C) 2014 Elsevier B.V. All rights reserved.
Preparation and Characterization of Ni-M (M: Ru, Rh, Pd) Nanoclusters as Efficient Catalysts for Hydrogen Evolution From Ammonia Borane Methanolysis
(Pergamon-elsevier Science Ltd, 2020) Tunc, Nihat; Rakap, Murat
Here, first-time preparation, characterization, and catalytic use of hydroxyapatite-supported nickel-based Ni-M (NiRu@HAP, NiRh@HAP, NiPd@HAP) nanoclusters in hydrogen evolution from methanolysis of ammonia borane is reported. Ni-M nanoclusters have been in-situ formed by reduction of hydroxyapatite-supported corresponding metal ions during methanolysis reaction of ammonia borane. The hydroxyapatite-supported Ni-M nanoclusters are isolated as stable solid materials to be characterized by advanced analytical techniques of ICP-OES, TEM, XPS, and XRD. They are found to be isolable, highly redispersible and reusable nanocatalysts for hydrogen evolution from ammonia borane methanolysis under ambient conditions. Ni20Ru80@HAP, Ni38Rh62@HAP, and Ni20Pd80@HAP nanoclusters have TOF values of 58.9, 120.3, and 25.2 min(-1), respectively, in the methanolysis of ammonia borane at 25 +/- 0.1 degrees C. Their apparent activation energy (E-a) values for the same reaction are calculated to be 65.9, 66.8, and 58.1 kJ/mol, respectively, for Ni20Ru80@HAP, Ni38Rh62@HAP, and Ni20Pd80@HAP nanoclusters. (C) 2020 Elsevier Ltd. All rights reserved.
Pvp-Stabilized Ru-Rh Nanoparticles as Highly Efficient Catalysts for Hydrogen Generation From Hydrolysis of Ammonia Borane
(Elsevier Science Sa, 2015) Rakap, Murat
Herein, the utilization of poly(N-vinyl-2-pyrrolidone)-protected ruthenium-rhodium nanoparticles (3.4 +/- 1.4 nm) as highly efficient catalysts in the hydrolysis of ammonia borane for hydrogen generation is reported. They are prepared by co-reduction of ruthenium and rhodium metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy-energy dispersive X-ray spectroscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. They are durable and highly efficient catalysts for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing average turnover frequency of 386 mol H-2 (mol cat)(-1) min(-1) and maximum hydrogen generation rate of 10,680 L H-2 min(-1) (mol cat)(-1). Poly(N-vinyl-2-pyrrolidone)-protected ruthenium-rhodium nanoparticles also provide activation energy of 47.4 +/- 2.1 kJ/mol for the hydrolysis of ammonia borane. (C) 2015 Elsevier B.V. All rights reserved.
Pvp-Stabilized Ru-Rh Nanoparticles as Highly Efficient Catalysts for Hydrogen Generation From Hydrolysis of Ammonia Borane (Vol 649, Pg 1025, 2015)
(Elsevier Science Sa, 2021) Rakap, Murat
Rh-M (M: Co, Cu, and Fe) Nanoclusters as Highly Efficient and Durable Catalysts for the Methanolysis of Ammonia Borane
(Royal Soc Chemistry, 2020) Abay, Bayram; Rakap, Murat
Herein, we report the preparation, characterization, and employment of hydroxyapatite-supported rhodium-based Rh-M (RhCo, RhCu, and RhFe) nanoclusters as cost-effective, highly efficient and reusable catalysts for hydrogen evolution from ammonia borane methanolysis. Rh-M@HA nanoclusters are formed by in situ reduction of hydroxyapatite-supported related metal cations during ammonia borane methanolysis after ion-exchange. The Rh-M@HA nanoclusters are easily obtained as very stable solids and identified by some advanced analytical techniques like ICP-OES, BET, TEM, XPS, and XRD. After experimental studies, they are found as highly isolable, redispersible, and reusable nanocatalysts to evolve hydrogen from ammonia borane methanolysis under mild conditions. From these three catalysts, the Rh51Co49@HA nanoclusters provide the highest turnover frequency (TOF) value of 193.7 min(-1) while the Rh26Cu74@HA and Rh45Fe55@HA nanoclusters have TOF values of 25.1 and 38.7 min(-1), respectively, in ammonia borane methanolysis at 25 +/- 0.1 degrees C. The apparent activation energies (E-a) of the Rh51Co49@HA, Rh26Cu74@HA, and Rh45Fe55@HA nanoclusters for the same reaction are calculated to be 52.7, 59.7, and 54.1 kJ mol(-1), respectively.
Surfactant-Aided Synthesis of Rhco Nanoclusters as Highly Effective and Recyclable Catalysts for the Hydrolysis of Methylamine Borane and Dimethylamine Borane
(Royal Soc Chemistry, 2020) Tunc, Nihat; Rakap, Murat
In the present study, the first ever and easy surfactant-aided synthesis of hexadecyltrimethyl ammonium bromide-stabilized RhCo nanoclusters (Rh0.63Co0.37@CTAB) and their employment as highly efficient, relatively cost-saving, and recyclable catalysts to generate hydrogen from the hydrolysis reactions of methylamine borane (MeAB) and dimethylamine borane (DMAB) are reported. The easy synthesis of Rh0.63Co0.37@CTAB nanoclusters is accomplished by synchronous reduction of appropriate rhodium and cobalt salts by sodium borohydride in the presence of CTAB as a surfactant in aqueous solution at room temperature. The Rh0.63Co0.37@CTAB nanoclusters are characterized by some techniques like ultraviolet-visible electronic absorption spectroscopy (UV-vis), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). They provide very remarkable turnover frequencies (TOFs) of 107.1 min(-1) and 142.9 min(-1) (8571.4 h(-1), best ever value) in the hydrolysis of MeAB and DMAB, respectively, even at very low temperatures. Their activation energies in the same reactions are calculated to be 55.3 kJ mol(-1) and 50.3 kJ mol(-1), respectively.