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Hiroshi Kitagawa - One of the best experts on this subject based on the ideXlab platform.
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shape dependent hydrogen storage properties in pd nanocrystals which does hydrogen prefer octahedron 111 or cube 100
Journal of the American Chemical Society, 2014Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, Masaki Takata, Ryuichi Ikeda, Shun Dekura, Tomokazu Yamamoto, Syo MatsumuraAbstract:Pd octahedrons and cubes enclosed by {111} and {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, in situ solid-state 2H NMR and hydrogen pressure–composition isotherm measurements. With these measurements, it was found that the exposed facets do not affect hydrogen-storage capacity; however, they significantly affect the absorption speed, with octahedral nanocrystals showing the faster response. The heat of adsorption of hydrogen and the hydrogen diffusion pathway were suggested to be dominant factors for hydrogen-absorption speed. Furthermore, in situ solid-state 2H NMR detected for the first time the state of 2H in a solid-solution (Pd + H) phase of Pd nanocrystals at rt.
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atomic level pd pt alloying and largely enhanced hydrogen storage capacity in bimetallic nanoparticles reconstructed from core shell structure by a process of hydrogen absorption desorption
Journal of the American Chemical Society, 2010Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray diffraction, energy dispersive spectra, solid-state 2H NMR measurement, and hydrogen pressure−composition isotherms. The successfully obtained Pd−Pt solid-solution nanoparticles with a Pt content of 8−21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles. Moreover, the hydrogen-storage capacity of Pd−Pt solid-solution nanoparticles can be tuned by changing the composition of Pd and Pt.
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atomic level pd au alloying and controllable hydrogen absorption properties in size controlled nanoparticles synthesized by hydrogen reduction
Chemical Communications, 2009Co-Authors: Hirokazu Kobayashi, Miho Yamauchi, Ryuichi Ikeda, Hiroshi KitagawaAbstract:Size-controlled atomic-level Pd–Au alloy nanoparticles have been synthesized with a wide range of atomic ratios by a facile method using H2 gas, and their controllable hydrogen-absorption properties have been studied from hydrogen pressure–composition isotherms and solid-state 2H NMR spectra.
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nanosize effects on hydrogen storage in palladium
Journal of Physical Chemistry C, 2008Co-Authors: Miho Yamauchi, Hiroshi Kitagawa, Ryuichi Ikeda, Masaki TakataAbstract:The size dependencies of the hydrogen-storage properties in polymer-coated Pd nanoparticles with diameters of 2.6 ± 0.4 and 7.0 ± 0.9 nm were investigated by a measurement of hydrogen pressure-composition isotherms. Their storage capacities per constituent Pd atom in the particles decreased with decreasing particle size, whereas the hydrogen concentrations in the two kinds of nanoparticles were almost the same and 1.2 times as much, respectively, as that in bulk palladium after counting zero hydrogen occupancy on the atoms in the first surface layer of the particles. Furthermore, apparent changes in hydrogen absorption behavior with decreasing particle size were observed, that is, a narrowing of the two-phase regions of solid-solution and hydride phases, the lowering of the equilibrium hydrogen pressure, and a decrease in the critical temperature of the two-phase state. By analyzing the isotherms, we quantitatively determined the heat of formation (ΔHα→β) and the entropy change (ΔSα→β) in the hydride form...
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hydrogen absorption in the core shell interface of pd pt nanoparticles
Journal of the American Chemical Society, 2008Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have investigated the hydrogen absorption behavior of Pd/Pt nanoparticles with a core/shell-type structure. From the results of the hydrogen pressure−composition (PC) isotherm and solid-state 2H NMR measurements, it was revealed that the Pd/Pt nanoparticles can absorb hydrogen, and most of the absorbed hydrogen atoms are situated around the interfacial region between the Pd core and the Pt shell of the Pd/Pt nanoparticles, indicating that the core/shell boundary plays an important role in the formation of the hydride phase of the Pd/Pt nanoparticles.
Masaki Takata - One of the best experts on this subject based on the ideXlab platform.
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shape dependent hydrogen storage properties in pd nanocrystals which does hydrogen prefer octahedron 111 or cube 100
Journal of the American Chemical Society, 2014Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, Masaki Takata, Ryuichi Ikeda, Shun Dekura, Tomokazu Yamamoto, Syo MatsumuraAbstract:Pd octahedrons and cubes enclosed by {111} and {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, in situ solid-state 2H NMR and hydrogen pressure–composition isotherm measurements. With these measurements, it was found that the exposed facets do not affect hydrogen-storage capacity; however, they significantly affect the absorption speed, with octahedral nanocrystals showing the faster response. The heat of adsorption of hydrogen and the hydrogen diffusion pathway were suggested to be dominant factors for hydrogen-absorption speed. Furthermore, in situ solid-state 2H NMR detected for the first time the state of 2H in a solid-solution (Pd + H) phase of Pd nanocrystals at rt.
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atomic level pd pt alloying and largely enhanced hydrogen storage capacity in bimetallic nanoparticles reconstructed from core shell structure by a process of hydrogen absorption desorption
Journal of the American Chemical Society, 2010Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray diffraction, energy dispersive spectra, solid-state 2H NMR measurement, and hydrogen pressure−composition isotherms. The successfully obtained Pd−Pt solid-solution nanoparticles with a Pt content of 8−21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles. Moreover, the hydrogen-storage capacity of Pd−Pt solid-solution nanoparticles can be tuned by changing the composition of Pd and Pt.
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nanosize effects on hydrogen storage in palladium
Journal of Physical Chemistry C, 2008Co-Authors: Miho Yamauchi, Hiroshi Kitagawa, Ryuichi Ikeda, Masaki TakataAbstract:The size dependencies of the hydrogen-storage properties in polymer-coated Pd nanoparticles with diameters of 2.6 ± 0.4 and 7.0 ± 0.9 nm were investigated by a measurement of hydrogen pressure-composition isotherms. Their storage capacities per constituent Pd atom in the particles decreased with decreasing particle size, whereas the hydrogen concentrations in the two kinds of nanoparticles were almost the same and 1.2 times as much, respectively, as that in bulk palladium after counting zero hydrogen occupancy on the atoms in the first surface layer of the particles. Furthermore, apparent changes in hydrogen absorption behavior with decreasing particle size were observed, that is, a narrowing of the two-phase regions of solid-solution and hydride phases, the lowering of the equilibrium hydrogen pressure, and a decrease in the critical temperature of the two-phase state. By analyzing the isotherms, we quantitatively determined the heat of formation (ΔHα→β) and the entropy change (ΔSα→β) in the hydride form...
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hydrogen absorption in the core shell interface of pd pt nanoparticles
Journal of the American Chemical Society, 2008Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have investigated the hydrogen absorption behavior of Pd/Pt nanoparticles with a core/shell-type structure. From the results of the hydrogen pressure−composition (PC) isotherm and solid-state 2H NMR measurements, it was revealed that the Pd/Pt nanoparticles can absorb hydrogen, and most of the absorbed hydrogen atoms are situated around the interfacial region between the Pd core and the Pt shell of the Pd/Pt nanoparticles, indicating that the core/shell boundary plays an important role in the formation of the hydride phase of the Pd/Pt nanoparticles.
Hunsoo Byun - One of the best experts on this subject based on the ideXlab platform.
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bubble point measurement for the co2 diethylene glycol diacrylate and co2 diethylene glycol dimethacrylate systems at high pressure
Korean Journal of Chemical Engineering, 2013Co-Authors: Soondo Yoon, Hunsoo ByunAbstract:Pressure-composition isotherms are measured by using a static apparatus for the phase behavior data for the CO2+diethylene glycol diacrylate (DEGDA) and CO2+diethylene glycol dimethacrylate (DEGDMA) systems. The experiments are performed at five temperatures of (313.2 to 393.2) K and pressures up to 28.3 MPa. The solubility of CO2 for the two systems decreases as the temperature increases at a fixed pressure. The CO2+DEGDA and CO2+ DEGDMA systems exhibit type-I phase behavior. The experimental results for the CO2+DEGDA and CO2+DEGDMA systems are correlated with Peng-Robinson equation of state using a mixing rule.
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phase behavior measurement for the ethylene glycol dimethacrylate in supercritical carbon dioxide at temperatures between 313 2 and 393 2 k and pressures from 5 8 to 22 mpa
Korean Journal of Chemical Engineering, 2010Co-Authors: Yoonseok Jang, Hunsoo ByunAbstract:High pressure experimental data are presented on the phase equilibrium of ethylene glycol dimethacrylate in supercritical carbon dioxide. Pressure-composition (P-x) isotherms were measured in static method at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 22.0MPa. This (carbon dioxide+ethylene glycol dimethacrylate) system has continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and ethylene glycol dimethacrylate. At a fixed pressure, the solubility of ethylene glycol dimethacrylate for the (carbon dioxide+ethylene glycol dimethacrylate) system increases with increasing temperature. The (carbon dioxide+ethylene glycol dimethacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide+ethylene glycol dimethacrylate) system is correlated with Peng-Robinson equation of state using mixing rule including two adjustable parameters. The critical property of ethylene glycol dimethacrylate is predicted with Joback and Lee-Kesler method.
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High pressure phase behavior for the propionitrile and butyronitrile in supercritical carbon dioxide
Journal of Industrial and Engineering Chemistry, 2010Co-Authors: Sung-hyun Kim, Mi-hwa Park, Jong Sung Lim, Hunsoo ByunAbstract:Abstract Pressure-composition isotherms for the (carbon dioxide + propionitrile) and (carbon dioxide + butyronitrile) systems are measured in static-type high pressure apparatus at several temperatures of 313.2, 333.2, 353.2, 373.2 and 393.2 K and at pressures range from 3.5 to 16.7 MPa. The carbon dioxide + nitriles systems have continuous critical mixture (local) curves that exhibit maximums in pressure–temperature space between the critical point of carbon dioxide and monomers (propionitrile or butyronitrile). At a fixed pressure, the solubility of propionitrile or butyronitrile for the two binary systems increases as the temperature increases. The (carbon dioxide + propionitrile) and (carbon dioxide + butyronitrile) systems exhibit type-I phase behavior. The experimental results for the (carbon dioxide + propionitrile) and (carbon dioxide + butyronitrile) systems are correlated with Peng–Robinson equation of state using mixing rule including two adjustable parameters.
Hirokazu Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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shape dependent hydrogen storage properties in pd nanocrystals which does hydrogen prefer octahedron 111 or cube 100
Journal of the American Chemical Society, 2014Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, Masaki Takata, Ryuichi Ikeda, Shun Dekura, Tomokazu Yamamoto, Syo MatsumuraAbstract:Pd octahedrons and cubes enclosed by {111} and {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, in situ solid-state 2H NMR and hydrogen pressure–composition isotherm measurements. With these measurements, it was found that the exposed facets do not affect hydrogen-storage capacity; however, they significantly affect the absorption speed, with octahedral nanocrystals showing the faster response. The heat of adsorption of hydrogen and the hydrogen diffusion pathway were suggested to be dominant factors for hydrogen-absorption speed. Furthermore, in situ solid-state 2H NMR detected for the first time the state of 2H in a solid-solution (Pd + H) phase of Pd nanocrystals at rt.
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atomic level pd pt alloying and largely enhanced hydrogen storage capacity in bimetallic nanoparticles reconstructed from core shell structure by a process of hydrogen absorption desorption
Journal of the American Chemical Society, 2010Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray diffraction, energy dispersive spectra, solid-state 2H NMR measurement, and hydrogen pressure−composition isotherms. The successfully obtained Pd−Pt solid-solution nanoparticles with a Pt content of 8−21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles. Moreover, the hydrogen-storage capacity of Pd−Pt solid-solution nanoparticles can be tuned by changing the composition of Pd and Pt.
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atomic level pd au alloying and controllable hydrogen absorption properties in size controlled nanoparticles synthesized by hydrogen reduction
Chemical Communications, 2009Co-Authors: Hirokazu Kobayashi, Miho Yamauchi, Ryuichi Ikeda, Hiroshi KitagawaAbstract:Size-controlled atomic-level Pd–Au alloy nanoparticles have been synthesized with a wide range of atomic ratios by a facile method using H2 gas, and their controllable hydrogen-absorption properties have been studied from hydrogen pressure–composition isotherms and solid-state 2H NMR spectra.
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hydrogen absorption in the core shell interface of pd pt nanoparticles
Journal of the American Chemical Society, 2008Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have investigated the hydrogen absorption behavior of Pd/Pt nanoparticles with a core/shell-type structure. From the results of the hydrogen pressure−composition (PC) isotherm and solid-state 2H NMR measurements, it was revealed that the Pd/Pt nanoparticles can absorb hydrogen, and most of the absorbed hydrogen atoms are situated around the interfacial region between the Pd core and the Pt shell of the Pd/Pt nanoparticles, indicating that the core/shell boundary plays an important role in the formation of the hydride phase of the Pd/Pt nanoparticles.
Miho Yamauchi - One of the best experts on this subject based on the ideXlab platform.
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atomic level pd pt alloying and largely enhanced hydrogen storage capacity in bimetallic nanoparticles reconstructed from core shell structure by a process of hydrogen absorption desorption
Journal of the American Chemical Society, 2010Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray diffraction, energy dispersive spectra, solid-state 2H NMR measurement, and hydrogen pressure−composition isotherms. The successfully obtained Pd−Pt solid-solution nanoparticles with a Pt content of 8−21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles. Moreover, the hydrogen-storage capacity of Pd−Pt solid-solution nanoparticles can be tuned by changing the composition of Pd and Pt.
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atomic level pd au alloying and controllable hydrogen absorption properties in size controlled nanoparticles synthesized by hydrogen reduction
Chemical Communications, 2009Co-Authors: Hirokazu Kobayashi, Miho Yamauchi, Ryuichi Ikeda, Hiroshi KitagawaAbstract:Size-controlled atomic-level Pd–Au alloy nanoparticles have been synthesized with a wide range of atomic ratios by a facile method using H2 gas, and their controllable hydrogen-absorption properties have been studied from hydrogen pressure–composition isotherms and solid-state 2H NMR spectra.
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nanosize effects on hydrogen storage in palladium
Journal of Physical Chemistry C, 2008Co-Authors: Miho Yamauchi, Hiroshi Kitagawa, Ryuichi Ikeda, Masaki TakataAbstract:The size dependencies of the hydrogen-storage properties in polymer-coated Pd nanoparticles with diameters of 2.6 ± 0.4 and 7.0 ± 0.9 nm were investigated by a measurement of hydrogen pressure-composition isotherms. Their storage capacities per constituent Pd atom in the particles decreased with decreasing particle size, whereas the hydrogen concentrations in the two kinds of nanoparticles were almost the same and 1.2 times as much, respectively, as that in bulk palladium after counting zero hydrogen occupancy on the atoms in the first surface layer of the particles. Furthermore, apparent changes in hydrogen absorption behavior with decreasing particle size were observed, that is, a narrowing of the two-phase regions of solid-solution and hydride phases, the lowering of the equilibrium hydrogen pressure, and a decrease in the critical temperature of the two-phase state. By analyzing the isotherms, we quantitatively determined the heat of formation (ΔHα→β) and the entropy change (ΔSα→β) in the hydride form...
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hydrogen absorption in the core shell interface of pd pt nanoparticles
Journal of the American Chemical Society, 2008Co-Authors: Hirokazu Kobayashi, Hiroshi Kitagawa, Miho Yamauchi, Yoshiki Kubota, Kenichi Kato, Masaki TakataAbstract:We have investigated the hydrogen absorption behavior of Pd/Pt nanoparticles with a core/shell-type structure. From the results of the hydrogen pressure−composition (PC) isotherm and solid-state 2H NMR measurements, it was revealed that the Pd/Pt nanoparticles can absorb hydrogen, and most of the absorbed hydrogen atoms are situated around the interfacial region between the Pd core and the Pt shell of the Pd/Pt nanoparticles, indicating that the core/shell boundary plays an important role in the formation of the hydride phase of the Pd/Pt nanoparticles.
