The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
David S. Sholl - One of the best experts on this subject based on the ideXlab platform.
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first principles prediction of new complex transition Metal Hydrides for high temperature applications
ChemInform, 2015Co-Authors: Kelly M Nicholson, David S. ShollAbstract:High-throughput screening by DFT and grand canonical linear programming (GCLP) methods are used to compute thermodynamic properties and phase diagrams of complex transition Metal Hydrides (CTMH) with a library of 149 proposed materials based on known prototype structures and charge balancing rules.
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first principles screening of complex transition Metal Hydrides for high temperature applications
ChemInform, 2015Co-Authors: Kelly M Nicholson, David S. ShollAbstract:Semi-automated thermodynamic and phase diagram calculations based on DFT and grand canonical linear programming (GCLP) methods are used to screen 102 ternary and quaternary complex transition Metal Hydrides (CTMHs) and 26 ternary saline Hydrides in a library of over 260 Metals, interMetallics, binary, and higher Hydrides to identify materials that release H2 at higher temperatures than the associated binary Hydrides and at elevated temperatures (T < 1000 K, 1 bar H2 overpressure).
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first principles prediction of new complex transition Metal Hydrides for high temperature applications
Inorganic Chemistry, 2014Co-Authors: Kelly M Nicholson, David S. ShollAbstract:Metal Hydrides with high thermodynamic stability are desirable for high-temperature applications, such as those that require high hydrogen release temperatures or low hydrogen overpressures. First-principles calculations have been used previously to identify complex transition Metal Hydrides (CTMHs) for high temperature use by screening materials with experimentally known structures. Here, we extend our previous screening of CTMHs with a library of 149 proposed materials based on known prototype structures and charge balancing rules. These proposed materials are typically related to known materials by cation substitution. Our semiautomated, high-throughput screening uses density functional theory (DFT) and grand canonical linear programming (GCLP) methods to compute thermodynamic properties and phase diagrams: 81 of the 149 materials are found to be thermodynamically stable. We identified seven proposed materials that release hydrogen at higher temperatures than the associated binary Hydrides and at high ...
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first principles screening of complex transition Metal Hydrides for high temperature applications
Inorganic Chemistry, 2014Co-Authors: Kelly M Nicholson, David S. ShollAbstract:Metal Hydrides with enhanced thermodynamic stability with respect to the associated binary Hydrides are useful for high temperature applications in which highly stable materials with low hydrogen overpressures are desired. Though several examples of complex transition Metal Hydrides (CTMHs) with such enhanced stability are known, little thermodynamic or phase stability information is available for this materials class. In this work, we use semiautomated thermodynamic and phase diagram calculations based on density functional theory (DFT) and grand canonical linear programming (GCLP) methods to screen 102 ternary and quaternary CTMHs and 26 ternary saline Hydrides in a library of over 260 Metals, interMetallics, binary, and higher Hydrides to identify materials that release hydrogen at higher temperatures than the associated binary Hydrides and at elevated temperatures, T > 1000 K, for 1 bar H2 overpressure. For computational efficiency, we employ a tiered screening approach based first on solid phase grou...
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large scale screening of Metal Hydrides for hydrogen storage from first principles calculations based on equilibrium reaction thermodynamics
Physical Chemistry Chemical Physics, 2011Co-Authors: Anant D Kulkarni, Karl J Johnson, David S. ShollAbstract:Systematic thermodynamics calculations based on density functional theory-calculated energies for crystalline solids have been a useful complement to experimental studies of hydrogen storage in Metal Hydrides. We report the most comprehensive set of thermodynamics calculations for mixtures of light Metal Hydrides to date by performing grand canonical linear programming screening on a database of 359 compounds, including 147 compounds not previously examined by us. This database is used to categorize the reaction thermodynamics of all mixtures containing any four non-H elements among Al, B, C, Ca, K, Li, Mg, N, Na, Sc, Si, Ti, and V. Reactions are categorized according to the amount of H2 that is released and the reaction's enthalpy. This approach identifies 74 distinct single step reactions having that a storage capacity >6 wt.% and zero temperature heats of reaction 15 ≤ ΔU0 ≤ 75 kJ mol−1 H2. Many of these reactions, however, are likely to be problematic experimentally because of the role of refractory compounds, B12H12-containing compounds, or carbon. The single most promising reaction identified in this way involves LiNH2/LiH/KBH4, storing 7.48 wt.% H2 and having ΔU0 = 43.6 kJ mol−1 H2. We also examined the complete range of reaction mixtures to identify multi-step reactions with useful properties; this yielded 23 multi-step reactions of potential interest.
Aaron M Appel - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic hydricity of transition Metal Hydrides
Chemical Reviews, 2016Co-Authors: Eric S Wiedner, Matthew B Chambers, Catherine L Pitman, Morris R Bullock, Alexander J M Miller, Aaron M AppelAbstract:Transition Metal Hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving Metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M–H bond to generate a hydride ion (H–). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential–pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition Metal Hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of Metal Hydrides sp...
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Thermodynamic Hydricity of Transition Metal Hydrides
Chemical reviews, 2016Co-Authors: Eric S Wiedner, Matthew B Chambers, Catherine L Pitman, Alexander J M Miller, R. Morris Bullock, Aaron M AppelAbstract:Transition Metal Hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving Metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M-H bond to generate a hydride ion (H(-)). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential-pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition Metal Hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of Metal Hydrides spans a range of more than 50 kcal/mol. Methods for using hydricity values to predict chemical reactivity are also discussed, including organic transformations, the reduction of CO2, and the production and oxidation of hydrogen.
Alexander J M Miller - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic hydricity of transition Metal Hydrides
Chemical Reviews, 2016Co-Authors: Eric S Wiedner, Matthew B Chambers, Catherine L Pitman, Morris R Bullock, Alexander J M Miller, Aaron M AppelAbstract:Transition Metal Hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving Metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M–H bond to generate a hydride ion (H–). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential–pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition Metal Hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of Metal Hydrides sp...
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Thermodynamic Hydricity of Transition Metal Hydrides
Chemical reviews, 2016Co-Authors: Eric S Wiedner, Matthew B Chambers, Catherine L Pitman, Alexander J M Miller, R. Morris Bullock, Aaron M AppelAbstract:Transition Metal Hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving Metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M-H bond to generate a hydride ion (H(-)). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential-pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition Metal Hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of Metal Hydrides spans a range of more than 50 kcal/mol. Methods for using hydricity values to predict chemical reactivity are also discussed, including organic transformations, the reduction of CO2, and the production and oxidation of hydrogen.
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trialkylborane assisted co2 reduction by late transition Metal Hydrides
Organometallics, 2011Co-Authors: Alexander J M Miller, Jay A Labinger, John E BercawAbstract:Trialkylborane additives promote reduction of CO2 to formate by bis(diphosphine) Ni(II) and Rh(III) hydride complexes. The late transition Metal Hydrides, which can be formed from dihydrogen, transfer hydride to CO2 to give a formate–borane adduct. The borane must be of appropriate Lewis acidity: weaker acids do not show significant hydride transfer enhancement, while stronger acids abstract hydride without CO2 reduction. The mechanism likely involves a pre-equilibrium hydride transfer followed by formation of a stabilizing formate–borane adduct.
Kelly M Nicholson - One of the best experts on this subject based on the ideXlab platform.
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first principles prediction of new complex transition Metal Hydrides for high temperature applications
ChemInform, 2015Co-Authors: Kelly M Nicholson, David S. ShollAbstract:High-throughput screening by DFT and grand canonical linear programming (GCLP) methods are used to compute thermodynamic properties and phase diagrams of complex transition Metal Hydrides (CTMH) with a library of 149 proposed materials based on known prototype structures and charge balancing rules.
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first principles screening of complex transition Metal Hydrides for high temperature applications
ChemInform, 2015Co-Authors: Kelly M Nicholson, David S. ShollAbstract:Semi-automated thermodynamic and phase diagram calculations based on DFT and grand canonical linear programming (GCLP) methods are used to screen 102 ternary and quaternary complex transition Metal Hydrides (CTMHs) and 26 ternary saline Hydrides in a library of over 260 Metals, interMetallics, binary, and higher Hydrides to identify materials that release H2 at higher temperatures than the associated binary Hydrides and at elevated temperatures (T < 1000 K, 1 bar H2 overpressure).
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first principles screening of complex transition Metal Hydrides for high temperature applications
Inorganic Chemistry, 2014Co-Authors: Kelly M Nicholson, David S. ShollAbstract:Metal Hydrides with enhanced thermodynamic stability with respect to the associated binary Hydrides are useful for high temperature applications in which highly stable materials with low hydrogen overpressures are desired. Though several examples of complex transition Metal Hydrides (CTMHs) with such enhanced stability are known, little thermodynamic or phase stability information is available for this materials class. In this work, we use semiautomated thermodynamic and phase diagram calculations based on density functional theory (DFT) and grand canonical linear programming (GCLP) methods to screen 102 ternary and quaternary CTMHs and 26 ternary saline Hydrides in a library of over 260 Metals, interMetallics, binary, and higher Hydrides to identify materials that release hydrogen at higher temperatures than the associated binary Hydrides and at elevated temperatures, T > 1000 K, for 1 bar H2 overpressure. For computational efficiency, we employ a tiered screening approach based first on solid phase grou...
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first principles prediction of new complex transition Metal Hydrides for high temperature applications
Inorganic Chemistry, 2014Co-Authors: Kelly M Nicholson, David S. ShollAbstract:Metal Hydrides with high thermodynamic stability are desirable for high-temperature applications, such as those that require high hydrogen release temperatures or low hydrogen overpressures. First-principles calculations have been used previously to identify complex transition Metal Hydrides (CTMHs) for high temperature use by screening materials with experimentally known structures. Here, we extend our previous screening of CTMHs with a library of 149 proposed materials based on known prototype structures and charge balancing rules. These proposed materials are typically related to known materials by cation substitution. Our semiautomated, high-throughput screening uses density functional theory (DFT) and grand canonical linear programming (GCLP) methods to compute thermodynamic properties and phase diagrams: 81 of the 149 materials are found to be thermodynamically stable. We identified seven proposed materials that release hydrogen at higher temperatures than the associated binary Hydrides and at high ...
Eric S Wiedner - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic hydricity of transition Metal Hydrides
Chemical Reviews, 2016Co-Authors: Eric S Wiedner, Matthew B Chambers, Catherine L Pitman, Morris R Bullock, Alexander J M Miller, Aaron M AppelAbstract:Transition Metal Hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving Metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M–H bond to generate a hydride ion (H–). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential–pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition Metal Hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of Metal Hydrides sp...
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Thermodynamic Hydricity of Transition Metal Hydrides
Chemical reviews, 2016Co-Authors: Eric S Wiedner, Matthew B Chambers, Catherine L Pitman, Alexander J M Miller, R. Morris Bullock, Aaron M AppelAbstract:Transition Metal Hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving Metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M-H bond to generate a hydride ion (H(-)). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential-pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition Metal Hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of Metal Hydrides spans a range of more than 50 kcal/mol. Methods for using hydricity values to predict chemical reactivity are also discussed, including organic transformations, the reduction of CO2, and the production and oxidation of hydrogen.