The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Gillian R Goward - One of the best experts on this subject based on the ideXlab platform.
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7li and 29si nmr enabled by high density cellulose based electrodes in the lithiation process in silicon and silicon monoxide anodes
Journal of Physical Chemistry C, 2019Co-Authors: Annica I Freytag, Allen D Pauric, Meng Jiang, Gillian R GowardAbstract:To meet the energy density requirement for our next-generation electric vehicle applications, new electrode materials with higher capacity are required. Silicon monoxide (a-SiO) is one of the most promising anode materials because it can provide 1500 mAh/g specific capacity compared to 372 mAh/g for graphite and nevertheless overcome some of the inherent structural disadvantages of its parent material, silicon (Si) itself. The present work discusses the electrochemical reaction mechanisms of lithium insertion into a-SiO using multinuclear solid-state NMR (nuclear magnetic resonance). An in situ 7Li NMR study on both Si and a-SiO using a jelly-roll-type battery design shows the intrinsic difference between the lithiation of those two materials. In addition, 29Si MAS (magic-angle spinning) NMR data obtained at 20 T provide sufficient sensitivity to acquire these spectra on electrode active materials, in spite of the Low Natural Abundance of 29Si. Additionally, the electrochemical method developed here using...
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li and si nmr enabled by high density cellulose based electrodes in the lithiation process in silicon and silicon monoxide anodes
The Journal of Physical Chemistry, 2019Co-Authors: Annica I Freytag, Allen D Pauric, Meng Jiang, Gillian R GowardAbstract:To meet the energy density requirement for our next-generation electric vehicle applications, new electrode materials with higher capacity are required. Silicon monoxide (a-SiO) is one of the most promising anode materials because it can provide 1500 mAh/g specific capacity compared to 372 mAh/g for graphite and nevertheless overcome some of the inherent structural disadvantages of its parent material, silicon (Si) itself. The present work discusses the electrochemical reaction mechanisms of lithium insertion into a-SiO using multinuclear solid-state NMR (nuclear magnetic resonance). An in situ ⁷Li NMR study on both Si and a-SiO using a jelly-roll-type battery design shows the intrinsic difference between the lithiation of those two materials. In addition, ²⁹Si MAS (magic-angle spinning) NMR data obtained at 20 T provide sufficient sensitivity to acquire these spectra on electrode active materials, in spite of the Low Natural Abundance of ²⁹Si. Additionally, the electrochemical method developed here using porous cellulosic substrates provides a means to substantially enhance the amount of active material available for the NMR study of the cycled anode materials as a function of charge state. We demonstrate that this unorthodox cell design achieves reasonable capacity retention for the a-SiO anodes, and we suggest that this approach could be applied to a wide range of electrode materials.
Annica I Freytag - One of the best experts on this subject based on the ideXlab platform.
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7li and 29si nmr enabled by high density cellulose based electrodes in the lithiation process in silicon and silicon monoxide anodes
Journal of Physical Chemistry C, 2019Co-Authors: Annica I Freytag, Allen D Pauric, Meng Jiang, Gillian R GowardAbstract:To meet the energy density requirement for our next-generation electric vehicle applications, new electrode materials with higher capacity are required. Silicon monoxide (a-SiO) is one of the most promising anode materials because it can provide 1500 mAh/g specific capacity compared to 372 mAh/g for graphite and nevertheless overcome some of the inherent structural disadvantages of its parent material, silicon (Si) itself. The present work discusses the electrochemical reaction mechanisms of lithium insertion into a-SiO using multinuclear solid-state NMR (nuclear magnetic resonance). An in situ 7Li NMR study on both Si and a-SiO using a jelly-roll-type battery design shows the intrinsic difference between the lithiation of those two materials. In addition, 29Si MAS (magic-angle spinning) NMR data obtained at 20 T provide sufficient sensitivity to acquire these spectra on electrode active materials, in spite of the Low Natural Abundance of 29Si. Additionally, the electrochemical method developed here using...
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li and si nmr enabled by high density cellulose based electrodes in the lithiation process in silicon and silicon monoxide anodes
The Journal of Physical Chemistry, 2019Co-Authors: Annica I Freytag, Allen D Pauric, Meng Jiang, Gillian R GowardAbstract:To meet the energy density requirement for our next-generation electric vehicle applications, new electrode materials with higher capacity are required. Silicon monoxide (a-SiO) is one of the most promising anode materials because it can provide 1500 mAh/g specific capacity compared to 372 mAh/g for graphite and nevertheless overcome some of the inherent structural disadvantages of its parent material, silicon (Si) itself. The present work discusses the electrochemical reaction mechanisms of lithium insertion into a-SiO using multinuclear solid-state NMR (nuclear magnetic resonance). An in situ ⁷Li NMR study on both Si and a-SiO using a jelly-roll-type battery design shows the intrinsic difference between the lithiation of those two materials. In addition, ²⁹Si MAS (magic-angle spinning) NMR data obtained at 20 T provide sufficient sensitivity to acquire these spectra on electrode active materials, in spite of the Low Natural Abundance of ²⁹Si. Additionally, the electrochemical method developed here using porous cellulosic substrates provides a means to substantially enhance the amount of active material available for the NMR study of the cycled anode materials as a function of charge state. We demonstrate that this unorthodox cell design achieves reasonable capacity retention for the a-SiO anodes, and we suggest that this approach could be applied to a wide range of electrode materials.
Alan Wong - One of the best experts on this subject based on the ideXlab platform.
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A Low-cost strategy for 43 Ca solid-state NMR spectroscopy
Chemical Science, 2011Co-Authors: Alan Wong, Thibault Charpentier, Pedro Aguiar, Dimitris SakellariouAbstract:Calcium-43 is a notoriously insensitive probe for nuclear magnetic resonance (NMR) due to its Low Natural Abundance and small magnetic moment. Up until today, the few performed 43Ca solid-state NMR studies used either highly expensive 43Ca-enriched samples, or time consuming experiments on bulk Natural Abundance samples. We introduce the application of a magic-angle spinning coil (MACS) detector for a Low-cost approach to 43Ca NMR spectroscopy of solid materials with high detection sensitivity. We demonstrate 1D and 2D 43Ca NMR spectra of a 1 mg 43Ca-enriched sample. The sample cost is about 150 €. The effect of off-resonance MACS is also presented here.
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A Low-cost strategy for 43Ca solid-state NMR spectroscopy
Chemical Science, 2011Co-Authors: Alan Wong, Pedro M. Aguiar, Thibault Charpentier, Dimitris SakellariouAbstract:Calcium-43 is a notoriously insensitive probe for nuclear magnetic resonance (NMR) due to its Low Natural Abundance and small magnetic moment. Up until today, the few performed 43Ca solid-state NMR studies used either highly expensive 43Ca-enriched samples, or time consuming experiments on bulk Natural Abundance samples. We introduce the application of a magic-angle spinning coil (MACS) detector for a Low-cost approach to 43Ca NMR spectroscopy of solid materials with high detection sensitivity. We demonstrate 1D and 2D 43Ca NMR spectra of a 1 mg 43Ca-enriched sample. The sample cost is about 150 €. The effect of off-resonance MACS is also presented here.
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Two-dimensional 43Ca–1H correlation solid-state NMR spectroscopy
Solid State Nuclear Magnetic Resonance, 2009Co-Authors: Alan Wong, Danielle Laurencin, Ray Dupree, Mark E. SmithAbstract:Calcium-43 (nuclear spin, S=7/2) is an NMR insensitive Low-?? quadrupolar nucleus and up until recently only one-dimensional solid-state 43Ca NMR spectra have been reported. Through-space correlation experiments are challenging between spin-frac(1, 2) and Low-?? quadrupolar nuclei because of the intrinsically weak dipolar interaction and the often-Low Natural Abundance of the quadrupolar nucleus. Rotary-resonance recoupling (R3) has recently been used to re-introduce hetero-nuclear dipolar interactions for sensitive high-?? quadrupolar nuclei, but has not yet been applied in the case of Low-?? half-integer quadrupolar nuclei. Here an effective and robust 2D 1H-43Ca NMR correlation experiment combining the R3 dipole-recoupling scheme with 2D HMQC is presented. It is demonstrated that the weak 43Ca-1H dipolar coupling in hydroxyapatite and oxy-hydroxyapatite can be readily re-introduced and that this recoupling scheme is more efficient than conventional cross-polarization transfer. Moreover, three 43Ca-1H dipolar coupled calcium environments are clearly resolved in the structurally unknown oxy-hydroxyapatite. This local information is not readily available from other techniques such as powder XRD and high resolution electron microscopy. R3-HMQC is also a desirable experiment because the set-up is simple and it can be applied using conventional multi-resonance probes. ?? 2008 Elsevier Inc. All rights reserved.
Christian Bonhomme - One of the best experts on this subject based on the ideXlab platform.
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new insights into the structure and chemistry of titan s tholins via13c and 15n solid state nuclear magnetic resonance spectroscopy
Icarus, 2012Co-Authors: Sylvie Derenne, Cristina Coelho, C Anquetil, Cyril Szopa, Aisha S Rahman, Paul F Mcmillan, Furio Cora, Chris J Pickard, E Quirico, Christian BonhommeAbstract:Tholins are complex C,N-containing organic compounds produced in the laboratory. They are considered to provide materials that are analogous to those responsible for the haze observed in Titan's atmosphere. These compounds present an astrobiological interest due to their ability to release amino acids upon hydrolysis. Their chemical structure has been investigated using a large number of techniques. However, to date no detailed nuclear magnetic resonance (NMR) study has been performed on these materials despite the high potential of this technique for investigating the environment of given nuclei. Here 13C and 15N solid state NMR spectroscopy was applied to obtain new insights into the chemical structure of tholins produced through plasma discharge in gaseous N2-CH4 mixtures designed to simulate the atmosphere of Titan. Due to the Low Natural Abundance of these isotopes, a 13C and 15N-enriched tholin sample was synthesized using isotopically enriched gas precursors. Various pulse sequences including 13C and 15N single pulse, 1H-13C and 1H-15N cross polarisation and 1H-15N-13C double cross polarisation were used. These techniques alLowed complete characterisation of the chemical and structural environments of the carbon and nitrogen atoms. The NMR assignments were supplemented and confirmed by ab initio electronic structure calculations for model structures and molecular fragments.
Dimitris Sakellariou - One of the best experts on this subject based on the ideXlab platform.
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A Low-cost strategy for 43 Ca solid-state NMR spectroscopy
Chemical Science, 2011Co-Authors: Alan Wong, Thibault Charpentier, Pedro Aguiar, Dimitris SakellariouAbstract:Calcium-43 is a notoriously insensitive probe for nuclear magnetic resonance (NMR) due to its Low Natural Abundance and small magnetic moment. Up until today, the few performed 43Ca solid-state NMR studies used either highly expensive 43Ca-enriched samples, or time consuming experiments on bulk Natural Abundance samples. We introduce the application of a magic-angle spinning coil (MACS) detector for a Low-cost approach to 43Ca NMR spectroscopy of solid materials with high detection sensitivity. We demonstrate 1D and 2D 43Ca NMR spectra of a 1 mg 43Ca-enriched sample. The sample cost is about 150 €. The effect of off-resonance MACS is also presented here.
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A Low-cost strategy for 43Ca solid-state NMR spectroscopy
Chemical Science, 2011Co-Authors: Alan Wong, Pedro M. Aguiar, Thibault Charpentier, Dimitris SakellariouAbstract:Calcium-43 is a notoriously insensitive probe for nuclear magnetic resonance (NMR) due to its Low Natural Abundance and small magnetic moment. Up until today, the few performed 43Ca solid-state NMR studies used either highly expensive 43Ca-enriched samples, or time consuming experiments on bulk Natural Abundance samples. We introduce the application of a magic-angle spinning coil (MACS) detector for a Low-cost approach to 43Ca NMR spectroscopy of solid materials with high detection sensitivity. We demonstrate 1D and 2D 43Ca NMR spectra of a 1 mg 43Ca-enriched sample. The sample cost is about 150 €. The effect of off-resonance MACS is also presented here.
