The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Christoph Langhammer - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamics of Hydride Formation and decomposition in supported sub-10 nm Pd nanoparticles of different sizes
Chemical Physics Letters, 2014Co-Authors: Carl Wadell, Vladimir P. Zhdanov, Torben Pingel, Eva Olsson, Igor Zoric, Christoph LanghammerAbstract:Hydrogen storage properties of supported Pd nanoparticles with average sizes in the range 2.7-7.6 nm were studied using indirect nanoplasmonic sensing. For each particle size, a series of isotherms was measured and, through Van't Hoff analysis, the changes in enthalpy upon Hydride Formation/decomposition were determined. Contrary to the expected decrease of the enthalpy, due to increasing importance of surface tension in smaller particles, we observe a very weak size dependence in the size range under consideration. We attribute this to a compensation effect due to an increased fraction of hydrogen atoms occupying energetically favorable subsurface sites in smaller nanoparticles.
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Hydride Formation in single palladium and magnesium nanoparticles studied by nanoplasmonic dark field scattering spectroscopy
Advanced Materials, 2011Co-Authors: Timur Shegai, Christoph LanghammerAbstract:Scrutinizing functional nanosystems and relating details in their size, chemistry, and geometry to functionality remains a significant experimental challenge. Following the concept of indirect nanoplasmonic sensing (INPS), the exploitation of truncated Au nanocones with functionalized tips, nanofabricated in a one step, are used as single nanoplasmonic sensors for dark-field scattering spectroscopy measurements of the Hydride Formation Au in single Pd and Mg nanoparticles.
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Size-dependent hysteresis in the Formation and decomposition of Hydride in metal nanoparticles
Chemical Physics Letters, 2010Co-Authors: Christoph Langhammer, Vladimir P. Zhdanov, Igor Zoric, Bengt Herbert KasemoAbstract:Using a novel indirect nanoplasmonic sensing platform, we have measured hydrogen absorption/desorption isotherms in Pd nanoparticles with an average diameter from 1.8 to 8 nm at 30 degrees C. The isotherms are fully reversible at relatively low and high pressures while at intermediate pressures there is hysteresis related to the Hydride Formation and decomposition. The hysteresis shrinks with decreasing particle size and becomes negligible for particles smaller than 2.5 nm. This feature has been explained in terms of a diminishing contribution of lattice strain to the free energy of Hydride Formation as the particle size goes down.
Tomasz J. Antosiewicz - One of the best experts on this subject based on the ideXlab platform.
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Hydride Formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
Nature Materials, 2015Co-Authors: Svetlana Syrenova, Ferry Anggoro Ardy Nugroho, Carl Wadell, Tina Gschneidtner, Giammarco Nalin, Dominika Świtlik, Yuri Antonio Diaz-fernandez, Fredrik Westerlund, Tomasz J. AntosiewiczAbstract:Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of Hydride Formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during Hydride Formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that Hydride decomposition either occurs incoherently or via different kinetic pathways. The physicochemical properties of nanoparticles can sometimes prove difficult to characterize. Using plasmonic nanospectroscopy, Hydride Formation thermodynamics in individual Pd nanocrystals are found to be nearly size- and shape-independent.
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Hydride Formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
Nature Materials, 2015Co-Authors: Svetlana Syrenova, Ferry Anggoro Ardy Nugroho, Carl Wadell, Tina Gschneidtner, Yuri Diaz Fernandez, Giammarco Nalin, Dominika Świtlik, Fredrik Westerlund, Tomasz J. AntosiewiczAbstract:Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of Hydride Formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during Hydride Formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that Hydride decomposition either occurs incoherently or via different kinetic pathways.
V.n. Verbetsky - One of the best experts on this subject based on the ideXlab platform.
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Hydride Formation in the TbNi0.4Co0.6-H2 System
Solid State Phenomena, 2016Co-Authors: E.y. Anikina, Yury Yaropolov, V. A. Somenkov, V.n. VerbetskyAbstract:The hydrogenation of TbNi0.4Co0.6 was studied by means of neutron diffraction and calorimetric method with use of the differential heat-conducting Tian-Calvet type calorimeter. It was determined that TbNi0.4Co0.6H3.8 crystallized in orthorhombic CrB-type structure (S.G. Cmcm). The Hydride Formation is accompanied with strong lattice expansion. In the structure TbNi0.4Co0.6D3.4 deuterium atoms occupy tetrahedral 8f-intersices, trigonal bipyramidal 4c-interstices and octahedral 4b-interstices. Dependence of the differential molar enthalpy of absorption (ΔHabs) vs. the hydrogen concentration in the metallic matrix was obtained at 50°C. It was ascertained that in the range of 0
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Interaction in (Ti,Sc)Fe2–H2 and (Zr,Sc)Fe2–H2 systems
Journal of Alloys and Compounds, 2007Co-Authors: T. A. Zotov, E. A. Movlaev, S.v. Mitrokhin, V.n. VerbetskyAbstract:Results of investigation of hydrogen sorption properties of Ti(Zr)xSc1 − xFe2 (x = 1, 0.8 and 0.5) alloys are presented. The measurements were performed for pressures up to 3000 atm. In case of titanium alloys Hydride Formation was established only for x = 0.5. Estimated equilibrium absorption pressure for x = 0.8 and 1.0 was too high for experimental limits of the device. In case of zirconium alloys Hydride Formation was found for all three concentrations. Absorption–desorption isotherms were measured for the first time for ZrFe2–H2 system. Calculated enthalpy of hydrogen desorption was found to be 21.3 kJ/mole H2. © 2007 Elsevier B.V. All rights reserved.
Carl Wadell - One of the best experts on this subject based on the ideXlab platform.
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Hydride Formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
Nature Materials, 2015Co-Authors: Svetlana Syrenova, Ferry Anggoro Ardy Nugroho, Carl Wadell, Tina Gschneidtner, Giammarco Nalin, Dominika Świtlik, Yuri Antonio Diaz-fernandez, Fredrik Westerlund, Tomasz J. AntosiewiczAbstract:Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of Hydride Formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during Hydride Formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that Hydride decomposition either occurs incoherently or via different kinetic pathways. The physicochemical properties of nanoparticles can sometimes prove difficult to characterize. Using plasmonic nanospectroscopy, Hydride Formation thermodynamics in individual Pd nanocrystals are found to be nearly size- and shape-independent.
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Hydride Formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
Nature Materials, 2015Co-Authors: Svetlana Syrenova, Ferry Anggoro Ardy Nugroho, Carl Wadell, Tina Gschneidtner, Yuri Diaz Fernandez, Giammarco Nalin, Dominika Świtlik, Fredrik Westerlund, Tomasz J. AntosiewiczAbstract:Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of Hydride Formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during Hydride Formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that Hydride decomposition either occurs incoherently or via different kinetic pathways.
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Thermodynamics of Hydride Formation and decomposition in supported sub-10 nm Pd nanoparticles of different sizes
Chemical Physics Letters, 2014Co-Authors: Carl Wadell, Vladimir P. Zhdanov, Torben Pingel, Eva Olsson, Igor Zoric, Christoph LanghammerAbstract:Hydrogen storage properties of supported Pd nanoparticles with average sizes in the range 2.7-7.6 nm were studied using indirect nanoplasmonic sensing. For each particle size, a series of isotherms was measured and, through Van't Hoff analysis, the changes in enthalpy upon Hydride Formation/decomposition were determined. Contrary to the expected decrease of the enthalpy, due to increasing importance of surface tension in smaller particles, we observe a very weak size dependence in the size range under consideration. We attribute this to a compensation effect due to an increased fraction of hydrogen atoms occupying energetically favorable subsurface sites in smaller nanoparticles.
Svetlana Syrenova - One of the best experts on this subject based on the ideXlab platform.
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Hydride Formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
Nature Materials, 2015Co-Authors: Svetlana Syrenova, Ferry Anggoro Ardy Nugroho, Carl Wadell, Tina Gschneidtner, Giammarco Nalin, Dominika Świtlik, Yuri Antonio Diaz-fernandez, Fredrik Westerlund, Tomasz J. AntosiewiczAbstract:Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of Hydride Formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during Hydride Formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that Hydride decomposition either occurs incoherently or via different kinetic pathways. The physicochemical properties of nanoparticles can sometimes prove difficult to characterize. Using plasmonic nanospectroscopy, Hydride Formation thermodynamics in individual Pd nanocrystals are found to be nearly size- and shape-independent.
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Hydride Formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape
Nature Materials, 2015Co-Authors: Svetlana Syrenova, Ferry Anggoro Ardy Nugroho, Carl Wadell, Tina Gschneidtner, Yuri Diaz Fernandez, Giammarco Nalin, Dominika Świtlik, Fredrik Westerlund, Tomasz J. AntosiewiczAbstract:Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of Hydride Formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during Hydride Formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that Hydride decomposition either occurs incoherently or via different kinetic pathways.
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Nanoplasmonic Spectroscopy of Single Nanoparticles Tracking Size and Shape Effects in Pd Hydride Formation
2014Co-Authors: Svetlana SyrenovaAbstract:Localized surface plasmon resonance (LSPR) is a phenomenon of collective oscillation of conduction electrons in metal nanoparticles smaller than the wavelength of light that is used for its excitation. Plasmonic metal nanoparticles are able to confine light to extremely small volumes around them, i.e. below the diffraction limit. This gives rise to strongly localized and enhanced electromagnetic fields in so-called “hot spots” of the plasmonic nanoparticle. These hot spots usually correspond to the edges, sharp corners or tips of monomer structures, and, in case of coupled multimer arrangements, to the antenna junctions. Plasmonic hot spots are highly advantageous for sensing, since any object that is inserted there will influence the optical resonance of the system via coupling to the local field. Placing a well-defined catalytic nanoobject in the hot spot of a plasmonic nanoantenna offers thus unique possibilities to obtain detailed inFormation about the role of specific features (e.g. facets, size, shape or relative abundance of low-coordinated sites, etc.) of that particle for its functionality/activity at the single particle level. Consequently, there is an increasing interest to use plasmonic antennas as a tool to investigate catalytic processes in/on single functional nanomaterials in situ. Single particle measurements are possible with the use of dark-field scattering spectroscopy, since plasmonic nanoparticles efficiently scatter light and are easily observable in the dark-field microscope. In this context, this work was dedicated to: 1) Development of a fabrication method for making plasmonic nanoantenna structures with the possibility to place a nanoparticle of interest (catalyst) in the hot spot of the antenna. 2) Investigation of the role of size and shape in Hydride Formation thermodynamics of wet-chemically synthesized single palladium (Pd) nanocrystals. The latter was possible by attaching the Pd nanocrystal to a plasmonic nanoantenna (gold sphere) by means of electrostatic self-assembly. The role of size was investigated for Pd nanocubes ranging from 20 to 50 nm. The role of shape was considered by modulating the Pd nanocrystal shape from cube to rod to octahedron.