The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hikaru Kobayashi - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen Generation by reaction of si nanopowder with neutral water
Journal of Nanoparticle Research, 2017Co-Authors: Yuki Kobayashi, Shinsuke Matsuda, Kentaro Imamura, Hikaru KobayashiAbstract:Si and its oxide are nonpoisonous materials, and thus, it can be taken for medical effects. We have developed a method of Generation of Hydrogen by use of reactions of Si nanopowder with water in the neutral pH region. Si nanopowder is fabricated by the simple bead milling method. Si nanopowder reacts with water to generate Hydrogen even in cases where pH is set at the neutral region between 7.0 and 8.6. The Hydrogen Generation rate strongly depends on pH and in the case of pH 8.0, ∼55 ml/g Hydrogen which corresponds to that contained in approximately 3 L saturated Hydrogen-rich water is generated in 1 h. The reaction rate for Hydrogen Generation greatly increases with pH, indicating that the reacting species is hydroxide ions. The change of pH after the Hydrogen Generation reaction is negligibly low compared with that estimated assuming that hydroxide ions are consumed by the reaction. From these results, we conclude the following reaction mechanism: Si nanopowder reacts with hydroxide ions in the rate-determining reaction to form Hydrogen molecules, SiO2, and electrons in the conduction band. Then, generated electrons are accepted by water molecules, resulting in production of Hydrogen molecules and hydroxide ions. The Hydrogen Generation rate strongly depends on the crystallite size of Si nanopowder, but not on the size of aggregates of Si nanopowder. The present study shows a possibility to use Si nanopowder for Hydrogen Generation in the body in order to eliminate hydroxyl radicals which cause various diseases.
-
Hydrogen Generation from water using Si nanopowder fabricated from swarf
Journal of Nanoparticle Research, 2016Co-Authors: Kentaro Imamura, Katsuya Kimura, Shunta Fujie, Hikaru KobayashiAbstract:Si nanopowder is fabricated from Si swarf by the simple beads milling method. Si nanopowder possesses the maximum crystallite size distribution at 7 nm and the average diameter of 12 nm. Fabricated Si nanopowder easily reacts with water, resulting in Generation of Hydrogen. The Hydrogen Generation rate strongly depends on pH value of the solutions and the temperature. When the pH value and the reaction temperature are set at 13.0 and 50 °C, respectively, the Hydrogen evolution rate in the initial 1 min reaches to ∼580 mL/min g, i.e., more than 1000 mL Hydrogen is generated from 1 g Si nanopowder in 2 min. Hydrogen Generation stops when a thick SiO_2 layer is formed on the surface of Si nanopowder. Analysis of evolved Hydrogen volume versus the reaction time shows that in the initial reaction period, dissolution of Si by OH^− ions to form soluble H_2SiO_4 ^2− ions and Hydrogen molecules is the dominant reaction, while in the subsequent period, the reaction of Si nanopowder with OH^− ions forms SiO_2, leading to Generation of Hydrogen molecules and electrons in the SiO_2 conduction band. Generated electrons are accepted by water molecules, resulting in formation of Hydrogen and OH^− ions.
Ping Wang - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen Generation from solvolysis of sodium borohydride in ethylene glycol water mixtures over a wide range of temperature
RSC Advances, 2013Co-Authors: Dawei Zhuang, Hongbin Dai, Ping WangAbstract:A high-performance Hydrogen Generation system with fast kinetics and a wide range of operational temperature is highly desirable for promoting the implementation of Hydrogen fuel cell technology. In the present study, we report a comparative study of the Hydrogen Generation properties from the reactions between sodium borohydride (NaBH4) and ethylene glycol (EG), water (H2O) or their mixture. Our study found that the glycolysis kinetics of NaBH4 is faster than the hydrolysis kinetics at moderate temperatures, but gets sluggish at low temperatures. As a solution, the combined usage of EG–water mixture as solvent and cobalt chloride (CoCl2) as a promoting additive enables the system to rapidly deliver H2 at low temperatures. A series of control experiments have been conducted to evaluate the Hydrogen Generation property dependence on EG concentration, CoCl2 amount and ratio of EG–H2O mixture to NaBH4. The reaction byproducts were characterized by powder X-ray diffraction and Fourier transform infrared spectroscopy techniques. Our study demonstrated a high-performance Hydrogen Generation system with a wide range of operational temperature, which may lay the foundation for developing practical Hydrogen source for mobile/portable applications.
-
controlled Hydrogen Generation by reaction of aluminum sodium hydroxide sodium stannate solid mixture with water
International Journal of Hydrogen Energy, 2012Co-Authors: Hongbin Dai, Dawei Zhuang, Haijie Xia, Ping WangAbstract:Aluminum/water reaction system has gained considerable attention for potential Hydrogen storage applications. In this paper, we report a new aluminum-based Hydrogen Generation system that is composed of aluminum/sodium hydroxide/sodium stannate solid mixture and water. This new system is characterized by the features as follows: the combined usage of sodium hydroxide and sodium stannate promoters, the use of solid fuel in a tablet form and the direct use of water as a reaction controlling agent. The factors that influence the Hydrogen Generation performance of the system were investigated. The optimized system exhibits a favorable combination of high Hydrogen Generation rate, high fuel conversion, rapid dynamic response, which makes it promising for portable Hydrogen source applications.
-
Hydrogen Generation from coupling reactions of sodium borohydride and aluminum powder with aqueous solution of cobalt chloride
Catalysis Today, 2011Co-Authors: Hongbin Dai, Xiangdong Kang, Ping WangAbstract:a b s t r a c t On-demand Hydrogen Generation from the hydrolysis reactions of chemical hydrides has gained everincreasing attention as a promising approach for providing mobile/portable Hydrogen sources. In this paper, we report a new chemical Hydrogen storage system that is composed of sodium borohydride (NaBH4)/aluminum (Al)/sodium hydroxide (NaOH) solid powder mixture and aqueous solution of cobalt chloride (CoCl2). Hydrogen Generation can be readily controlled by regulating the contact of the aqueous solution with the solid powder mixture. In comparison with the conventional NaBH4/H2O or Al/H2O systems, the newly developed dual-solid-fuel system exhibits distinct advantages in Hydrogen storage density, Hydrogen Generation rate and fuel conversion. Additionally, the dual-solid-fuel system shows satisfactory transient response. The factors influencing the Hydrogen Generation performance of the system were studied. The reaction by-products were characterized using powder X-ray diffraction and Fourier transform infrared spectroscopy techniques. Our study demonstrated a high-performance dual-solid-fuel Hydrogen Generation system, and may lay a foundation for developing practical Hydrogen generators for mobile/portable applications. © 2010 Elsevier B.V. All rights reserved.
-
Hydrogen Generation from sodium borohydride solution using a ruthenium supported on graphite catalyst
International Journal of Hydrogen Energy, 2010Co-Authors: Yan Liang, Hongbin Dai, Ping Wang, Huiming ChengAbstract:The catalyst with high activity and durability plays a crucial role in the Hydrogen Generation systems for the portable fuel cell generators. In the present study, a ruthenium supported on graphite catalyst (Ru/G) for Hydrogen Generation from sodium borohydride (NaBH(4)) solution is prepared by a modified impregnation method. This is done by surface pretreatment with NH(2) functionalization via silanization, followed by adsorption of Ru (III) ion onto the surface, and then reduced by a reducing agent. The obtained catalyst is characterized by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Very uniform Ru nanoparticles with sizes of about 10 nm are chemically bonded on the graphite surface. The hydrolysis kinetics measurements show that the concentrations of NaBH4 and NaOH all exert considerable influence on the catalytic activity of Ru/G catalyst towards the hydrolysis reaction of NaBH(4). A Hydrogen Generation rate of 32.3 L min(-1) g(-1) (Ru) in a 10 wt.% NaBH(4) + 5 wt.% NaOH solution has been achieved, which is comparable to other noble catalysts that have been reported. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
-
high performance cobalt tungsten boron catalyst supported on ni foam for Hydrogen Generation from alkaline sodium borohydride solution
International Journal of Hydrogen Energy, 2008Co-Authors: Hongbin Dai, Ping Wang, Yan Liang, Xiangdong Yao, Thomas E Rufford, Huiming ChengAbstract:Low cost and catalytically effective transition metal catalysts are highly wanted in developing on-demand Hydrogen Generation system for practical onboard application. By using a modified electroless plating method, we have prepared a robust Co–W–B amorphous catalyst supported on Ni foam (Co–W–B/Ni foam catalyst) that is highly effective for catalyzing Hydrogen Generation from alkaline NaBH4 solution. It was found that the plating times, calcination temperature, NaBH4 and NaOH concentrations all exert considerable influence on the catalytic effectiveness of Co–W–B/Ni foam catalyst towards the hydrolysis reaction of NaBH4. Via optimizing these preparation and reaction conditions, a Hydrogen Generation rate of 15 L/min g (Co–W–B) has been achieved, which is comparable to the highest level of noble metal catalyst. In consistent with the observed pronounced catalytic activity, the activation energy of the hydrolysis reaction using Co–W–B/Ni foam catalyst was determined to be only 29 kJ/mol. Based on the phase analysis and structural characterization results, the mechanism underlying the observed dependence of catalytic effectiveness on the calcination temperature was discussed.
Hongbin Dai - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen Generation from solvolysis of sodium borohydride in ethylene glycol water mixtures over a wide range of temperature
RSC Advances, 2013Co-Authors: Dawei Zhuang, Hongbin Dai, Ping WangAbstract:A high-performance Hydrogen Generation system with fast kinetics and a wide range of operational temperature is highly desirable for promoting the implementation of Hydrogen fuel cell technology. In the present study, we report a comparative study of the Hydrogen Generation properties from the reactions between sodium borohydride (NaBH4) and ethylene glycol (EG), water (H2O) or their mixture. Our study found that the glycolysis kinetics of NaBH4 is faster than the hydrolysis kinetics at moderate temperatures, but gets sluggish at low temperatures. As a solution, the combined usage of EG–water mixture as solvent and cobalt chloride (CoCl2) as a promoting additive enables the system to rapidly deliver H2 at low temperatures. A series of control experiments have been conducted to evaluate the Hydrogen Generation property dependence on EG concentration, CoCl2 amount and ratio of EG–H2O mixture to NaBH4. The reaction byproducts were characterized by powder X-ray diffraction and Fourier transform infrared spectroscopy techniques. Our study demonstrated a high-performance Hydrogen Generation system with a wide range of operational temperature, which may lay the foundation for developing practical Hydrogen source for mobile/portable applications.
-
controlled Hydrogen Generation by reaction of aluminum sodium hydroxide sodium stannate solid mixture with water
International Journal of Hydrogen Energy, 2012Co-Authors: Hongbin Dai, Dawei Zhuang, Haijie Xia, Ping WangAbstract:Aluminum/water reaction system has gained considerable attention for potential Hydrogen storage applications. In this paper, we report a new aluminum-based Hydrogen Generation system that is composed of aluminum/sodium hydroxide/sodium stannate solid mixture and water. This new system is characterized by the features as follows: the combined usage of sodium hydroxide and sodium stannate promoters, the use of solid fuel in a tablet form and the direct use of water as a reaction controlling agent. The factors that influence the Hydrogen Generation performance of the system were investigated. The optimized system exhibits a favorable combination of high Hydrogen Generation rate, high fuel conversion, rapid dynamic response, which makes it promising for portable Hydrogen source applications.
-
Hydrogen Generation from coupling reactions of sodium borohydride and aluminum powder with aqueous solution of cobalt chloride
Catalysis Today, 2011Co-Authors: Hongbin Dai, Xiangdong Kang, Ping WangAbstract:a b s t r a c t On-demand Hydrogen Generation from the hydrolysis reactions of chemical hydrides has gained everincreasing attention as a promising approach for providing mobile/portable Hydrogen sources. In this paper, we report a new chemical Hydrogen storage system that is composed of sodium borohydride (NaBH4)/aluminum (Al)/sodium hydroxide (NaOH) solid powder mixture and aqueous solution of cobalt chloride (CoCl2). Hydrogen Generation can be readily controlled by regulating the contact of the aqueous solution with the solid powder mixture. In comparison with the conventional NaBH4/H2O or Al/H2O systems, the newly developed dual-solid-fuel system exhibits distinct advantages in Hydrogen storage density, Hydrogen Generation rate and fuel conversion. Additionally, the dual-solid-fuel system shows satisfactory transient response. The factors influencing the Hydrogen Generation performance of the system were studied. The reaction by-products were characterized using powder X-ray diffraction and Fourier transform infrared spectroscopy techniques. Our study demonstrated a high-performance dual-solid-fuel Hydrogen Generation system, and may lay a foundation for developing practical Hydrogen generators for mobile/portable applications. © 2010 Elsevier B.V. All rights reserved.
-
Hydrogen Generation from sodium borohydride solution using a ruthenium supported on graphite catalyst
International Journal of Hydrogen Energy, 2010Co-Authors: Yan Liang, Hongbin Dai, Ping Wang, Huiming ChengAbstract:The catalyst with high activity and durability plays a crucial role in the Hydrogen Generation systems for the portable fuel cell generators. In the present study, a ruthenium supported on graphite catalyst (Ru/G) for Hydrogen Generation from sodium borohydride (NaBH(4)) solution is prepared by a modified impregnation method. This is done by surface pretreatment with NH(2) functionalization via silanization, followed by adsorption of Ru (III) ion onto the surface, and then reduced by a reducing agent. The obtained catalyst is characterized by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Very uniform Ru nanoparticles with sizes of about 10 nm are chemically bonded on the graphite surface. The hydrolysis kinetics measurements show that the concentrations of NaBH4 and NaOH all exert considerable influence on the catalytic activity of Ru/G catalyst towards the hydrolysis reaction of NaBH(4). A Hydrogen Generation rate of 32.3 L min(-1) g(-1) (Ru) in a 10 wt.% NaBH(4) + 5 wt.% NaOH solution has been achieved, which is comparable to other noble catalysts that have been reported. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
-
high performance cobalt tungsten boron catalyst supported on ni foam for Hydrogen Generation from alkaline sodium borohydride solution
International Journal of Hydrogen Energy, 2008Co-Authors: Hongbin Dai, Ping Wang, Yan Liang, Xiangdong Yao, Thomas E Rufford, Huiming ChengAbstract:Low cost and catalytically effective transition metal catalysts are highly wanted in developing on-demand Hydrogen Generation system for practical onboard application. By using a modified electroless plating method, we have prepared a robust Co–W–B amorphous catalyst supported on Ni foam (Co–W–B/Ni foam catalyst) that is highly effective for catalyzing Hydrogen Generation from alkaline NaBH4 solution. It was found that the plating times, calcination temperature, NaBH4 and NaOH concentrations all exert considerable influence on the catalytic effectiveness of Co–W–B/Ni foam catalyst towards the hydrolysis reaction of NaBH4. Via optimizing these preparation and reaction conditions, a Hydrogen Generation rate of 15 L/min g (Co–W–B) has been achieved, which is comparable to the highest level of noble metal catalyst. In consistent with the observed pronounced catalytic activity, the activation energy of the hydrolysis reaction using Co–W–B/Ni foam catalyst was determined to be only 29 kJ/mol. Based on the phase analysis and structural characterization results, the mechanism underlying the observed dependence of catalytic effectiveness on the calcination temperature was discussed.
V I Simagina - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen storage systems based on solid state nabh4 co composite effect of catalyst precursor on Hydrogen Generation rate
Renewable Energy, 2020Co-Authors: O V Netskina, E S Tayban, Oxana V Komova, I P Prosvirin, V I SimaginaAbstract:Abstract Tablets on the basis of sodium borohydride and cobalt compounds (CoCl2·6H2O, Co(CH3COO)2·4H2O, Co3O4 and anhydrous CoSO4) have been studied as Hydrogen Generation materials. The kinetics of sodium borohydride hydrolysis upon contact of the tablets with water has been investigated. Adsorption and reaction constants have been determined for each of the catalysts using the Langmuir-Hinshelwood model which allowed us to estimate the contribution of BH4‾ adsorption to the overall rate of Hydrogen Generation. It was noted that the nature of the catalyst precursor has an influence not only on the specific surface area of the in situ forming catalytically active phase, the particle size of the catalyst, the degree of reduction of cobalt compounds by sodium borohydride but also on the adsorption of BH4‾ anions from the reaction medium on the catalyst surface.
-
solid state nabh4 co composite as Hydrogen storage material effect of the pressing pressure on Hydrogen Generation rate
Energies, 2019Co-Authors: O V Netskina, E S Tayban, Anna M Ozerova, Oxana V Komova, V I SimaginaAbstract:A solid-state NaBH4/Co composite has been employed as a Hydrogen-generating material, as an alternative to sodium borohydride solutions, in the long storage of Hydrogen. Hydrogen Generation begins in the presence of cobalt-based catalysts, immediately after water is added to a NaBH4/Co composite, as a result of sodium borohydride hydrolysis. The Hydrogen Generation rate has been investigated as a function of the pressure used to press Hydrogen-generating composites from a mechanical mixture of the hydride and cobalt chloride hexahydrate. The Hydrogen Generation rate was observed to increase with the increase of this pressure. Pre-reduction of the cobalt chloride, using a sodium borohydride solution, leveled this dependence with a two-fold decrease in the gas Generation rate. According to TEM and XPS data, oxidation of the particles of the pre-reduced cobalt catalyst took place during preparation of the composites, and it is this oxidation that appears to be the main reason for its low activity in sodium borohydride hydrolysis.
-
Solid-State NaBH4/Co Composite as Hydrogen Storage Material: Effect of the Pressing Pressure on Hydrogen Generation Rate
MDPI AG, 2019Co-Authors: O V Netskina, E S Tayban, Anna M Ozerova, Oxana V Komova, V I SimaginaAbstract:A solid-state NaBH4/Co composite has been employed as a Hydrogen-generating material, as an alternative to sodium borohydride solutions, in the long storage of Hydrogen. Hydrogen Generation begins in the presence of cobalt-based catalysts, immediately after water is added to a NaBH4/Co composite, as a result of sodium borohydride hydrolysis. The Hydrogen Generation rate has been investigated as a function of the pressure used to press Hydrogen-generating composites from a mechanical mixture of the hydride and cobalt chloride hexahydrate. The Hydrogen Generation rate was observed to increase with the increase of this pressure. Pre-reduction of the cobalt chloride, using a sodium borohydride solution, leveled this dependence with a two-fold decrease in the gas Generation rate. According to TEM and XPS data, oxidation of the particles of the pre-reduced cobalt catalyst took place during preparation of the composites, and it is this oxidation that appears to be the main reason for its low activity in sodium borohydride hydrolysis
Kentaro Imamura - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen Generation by reaction of si nanopowder with neutral water
Journal of Nanoparticle Research, 2017Co-Authors: Yuki Kobayashi, Shinsuke Matsuda, Kentaro Imamura, Hikaru KobayashiAbstract:Si and its oxide are nonpoisonous materials, and thus, it can be taken for medical effects. We have developed a method of Generation of Hydrogen by use of reactions of Si nanopowder with water in the neutral pH region. Si nanopowder is fabricated by the simple bead milling method. Si nanopowder reacts with water to generate Hydrogen even in cases where pH is set at the neutral region between 7.0 and 8.6. The Hydrogen Generation rate strongly depends on pH and in the case of pH 8.0, ∼55 ml/g Hydrogen which corresponds to that contained in approximately 3 L saturated Hydrogen-rich water is generated in 1 h. The reaction rate for Hydrogen Generation greatly increases with pH, indicating that the reacting species is hydroxide ions. The change of pH after the Hydrogen Generation reaction is negligibly low compared with that estimated assuming that hydroxide ions are consumed by the reaction. From these results, we conclude the following reaction mechanism: Si nanopowder reacts with hydroxide ions in the rate-determining reaction to form Hydrogen molecules, SiO2, and electrons in the conduction band. Then, generated electrons are accepted by water molecules, resulting in production of Hydrogen molecules and hydroxide ions. The Hydrogen Generation rate strongly depends on the crystallite size of Si nanopowder, but not on the size of aggregates of Si nanopowder. The present study shows a possibility to use Si nanopowder for Hydrogen Generation in the body in order to eliminate hydroxyl radicals which cause various diseases.
-
Hydrogen Generation from water using Si nanopowder fabricated from swarf
Journal of Nanoparticle Research, 2016Co-Authors: Kentaro Imamura, Katsuya Kimura, Shunta Fujie, Hikaru KobayashiAbstract:Si nanopowder is fabricated from Si swarf by the simple beads milling method. Si nanopowder possesses the maximum crystallite size distribution at 7 nm and the average diameter of 12 nm. Fabricated Si nanopowder easily reacts with water, resulting in Generation of Hydrogen. The Hydrogen Generation rate strongly depends on pH value of the solutions and the temperature. When the pH value and the reaction temperature are set at 13.0 and 50 °C, respectively, the Hydrogen evolution rate in the initial 1 min reaches to ∼580 mL/min g, i.e., more than 1000 mL Hydrogen is generated from 1 g Si nanopowder in 2 min. Hydrogen Generation stops when a thick SiO_2 layer is formed on the surface of Si nanopowder. Analysis of evolved Hydrogen volume versus the reaction time shows that in the initial reaction period, dissolution of Si by OH^− ions to form soluble H_2SiO_4 ^2− ions and Hydrogen molecules is the dominant reaction, while in the subsequent period, the reaction of Si nanopowder with OH^− ions forms SiO_2, leading to Generation of Hydrogen molecules and electrons in the SiO_2 conduction band. Generated electrons are accepted by water molecules, resulting in formation of Hydrogen and OH^− ions.
