The Experts below are selected from a list of 17844 Experts worldwide ranked by ideXlab platform
Chengjun Sun - One of the best experts on this subject based on the ideXlab platform.
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Stanislaw H Nowak, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, Chengjun SunAbstract:Anion redox in lithium transition-metal oxides such as Li2RuO3 and Li2MnO3 has catalyzed intensive research efforts to find transition-metal oxides with anion redox that may boost the energy densit...
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, S Nowak, Chengjun SunAbstract:Anion redox in lithium transition metal oxides such as Li2RuO3 and Li2MnO3, has catalyzed intensive research efforts to find transition metal oxides with anion redox that may boost the energy density of lithium-ion batteries. The physical origin of observed anion redox remains debated, and more direct experimental evidence is needed. In this work, we have shown Electronic Signatures of oxygen-oxygen coupling, direct evidence central to lattice oxygen redox (O2-/(O2)n-), in charged Li2-xRuO3 after Ru oxidation (Ru4+/Ru5+) upon first-electron removal with lithium de-intercalation. Experimental Ru L3-edge high-energy-resolution fluorescence detected X-ray absorption spectra (HERFD-XAS), supported by ab-initio simulations, revealed that the increased intensity in the high-energy shoulder upon lithium de-intercalation resulted from increased O-O coupling, inducing (O-O) σ*-like states with π overlap with Ru d-manifolds, in agreement with O K-edge XAS spectra. Experimental and simulated O K-edge X-ray emission spectra (XES) further supported this observation with the broadening of the oxygen non-bonding feature upon charging, also originated from (O-O) σ* states. This lattice oxygen redox of Li2-xRuO3 was accompanied by a small amount of O2 evolution in the first charge from differential electrochemistry mass spectrometry (DEMS) but diminished in the subsequent cycles, in agreement with the more reduced states of Ru in later cycles from Ru L3-edge HERFD-XAS. These observations indicated that Ru redox contributed more to discharge capacities after the first cycle. This study has pinpointed the key spectral fingerprints related to lattice oxygen redox from a molecular level and constructed a transferrable framework to rationally interpret the spectroscopic features by combining advanced experiments and theoretical calculations to design materials for Li-ion batteries and electrocatalysis applications.
Pinar Karayaylali - One of the best experts on this subject based on the ideXlab platform.
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Stanislaw H Nowak, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, Chengjun SunAbstract:Anion redox in lithium transition-metal oxides such as Li2RuO3 and Li2MnO3 has catalyzed intensive research efforts to find transition-metal oxides with anion redox that may boost the energy densit...
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, S Nowak, Chengjun SunAbstract:Anion redox in lithium transition metal oxides such as Li2RuO3 and Li2MnO3, has catalyzed intensive research efforts to find transition metal oxides with anion redox that may boost the energy density of lithium-ion batteries. The physical origin of observed anion redox remains debated, and more direct experimental evidence is needed. In this work, we have shown Electronic Signatures of oxygen-oxygen coupling, direct evidence central to lattice oxygen redox (O2-/(O2)n-), in charged Li2-xRuO3 after Ru oxidation (Ru4+/Ru5+) upon first-electron removal with lithium de-intercalation. Experimental Ru L3-edge high-energy-resolution fluorescence detected X-ray absorption spectra (HERFD-XAS), supported by ab-initio simulations, revealed that the increased intensity in the high-energy shoulder upon lithium de-intercalation resulted from increased O-O coupling, inducing (O-O) σ*-like states with π overlap with Ru d-manifolds, in agreement with O K-edge XAS spectra. Experimental and simulated O K-edge X-ray emission spectra (XES) further supported this observation with the broadening of the oxygen non-bonding feature upon charging, also originated from (O-O) σ* states. This lattice oxygen redox of Li2-xRuO3 was accompanied by a small amount of O2 evolution in the first charge from differential electrochemistry mass spectrometry (DEMS) but diminished in the subsequent cycles, in agreement with the more reduced states of Ru in later cycles from Ru L3-edge HERFD-XAS. These observations indicated that Ru redox contributed more to discharge capacities after the first cycle. This study has pinpointed the key spectral fingerprints related to lattice oxygen redox from a molecular level and constructed a transferrable framework to rationally interpret the spectroscopic features by combining advanced experiments and theoretical calculations to design materials for Li-ion batteries and electrocatalysis applications.
Michael Bauer - One of the best experts on this subject based on the ideXlab platform.
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mode resolved reciprocal space mapping of electron phonon interaction in the weyl semimetal candidate td wte2
Nature Communications, 2020Co-Authors: Petra Hein, Stephan Jauernik, Hermann Erk, L X Yang, Yan Sun, Claudia Felser, Michael BauerAbstract:The excitation of coherent phonons provides unique capabilities to control fundamental properties of quantum materials on ultrafast time scales. Recently, it was predicted that a topologically protected Weyl semimetal phase in the transition metal dichalcogenide Td-WTe2 can be controlled and, ultimately, be destroyed upon the coherent excitation of an interlayer shear mode. By monitoring Electronic structure changes with femtosecond resolution, we provide here direct experimental evidence that the shear mode acts on the Electronic states near the phase-defining Weyl points. Furthermore, we observe a periodic reduction in the spin splitting of bands, a distinct Electronic Signature of the Weyl phase-stabilizing non-centrosymmetric Td ground state of WTe2. The comparison with higher-frequency coherent phonon modes finally proves the shear mode-selectivity of the observed changes in the Electronic structure. Our real-time observations reveal direct experimental insights into Electronic processes that are of vital importance for a coherent phonon-induced topological phase transition in Td-WTe2. It is predicted that topological phase transitions in quantum materials can be triggered by selective excitation of coherent phonons. Upon excitation of a shear mode, Hein et al. observe distinct perturbations of Electronic Weyl semimetal fingerprints in Td-WTe2.
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mode resolved reciprocal space mapping of electron phonon interaction in the weyl semimetal candidate td wte _2
arXiv: Materials Science, 2019Co-Authors: Petra Hein, Stephan Jauernik, Hermann Erk, L X Yang, Yan Sun, Claudia Felser, Michael BauerAbstract:The selective excitation of coherent phonons provides unique capabilities to control fundamental properties of quantum materials on ultrafast time scales. For instance, in the presence of strong electron-phonon coupling, the Electronic band structure can become substantially modulated. Recently, it was predicted that by this means even topologically protected states of matter can be manipulated and, ultimately, be destroyed: For the layered transition metal dichalcogenide Td-WTe$_2$, pairs of Weyl points are expected to annihilate as an interlayer shear mode drives the crystalline structure towards a centrosymmetric phase. By monitoring the changes in the Electronic structure of Td-WTe$_2$ with femtosecond resolution, we provide here direct experimental evidence that the coherent excitation of the shear mode acts on the Electronic states near the Weyl points. Band structure data in comparison with our results imply, furthermore, the periodic reduction in the spin splitting of bands near the Fermi energy, a distinct Electronic Signature of the non-centrosymmetric Td ground state of WTe$_2$. The comparison with higher-frequency coherent phonon modes finally proves the shear mode-selectivity of the observed changes in the Electronic structure. Our real-time observations reveal direct experimental insights into Electronic processes that are of vital importance for a coherent phonon-induced topological phase transition in Td-WTe$_2$.
Livia Giordano - One of the best experts on this subject based on the ideXlab platform.
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Stanislaw H Nowak, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, Chengjun SunAbstract:Anion redox in lithium transition-metal oxides such as Li2RuO3 and Li2MnO3 has catalyzed intensive research efforts to find transition-metal oxides with anion redox that may boost the energy densit...
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, S Nowak, Chengjun SunAbstract:Anion redox in lithium transition metal oxides such as Li2RuO3 and Li2MnO3, has catalyzed intensive research efforts to find transition metal oxides with anion redox that may boost the energy density of lithium-ion batteries. The physical origin of observed anion redox remains debated, and more direct experimental evidence is needed. In this work, we have shown Electronic Signatures of oxygen-oxygen coupling, direct evidence central to lattice oxygen redox (O2-/(O2)n-), in charged Li2-xRuO3 after Ru oxidation (Ru4+/Ru5+) upon first-electron removal with lithium de-intercalation. Experimental Ru L3-edge high-energy-resolution fluorescence detected X-ray absorption spectra (HERFD-XAS), supported by ab-initio simulations, revealed that the increased intensity in the high-energy shoulder upon lithium de-intercalation resulted from increased O-O coupling, inducing (O-O) σ*-like states with π overlap with Ru d-manifolds, in agreement with O K-edge XAS spectra. Experimental and simulated O K-edge X-ray emission spectra (XES) further supported this observation with the broadening of the oxygen non-bonding feature upon charging, also originated from (O-O) σ* states. This lattice oxygen redox of Li2-xRuO3 was accompanied by a small amount of O2 evolution in the first charge from differential electrochemistry mass spectrometry (DEMS) but diminished in the subsequent cycles, in agreement with the more reduced states of Ru in later cycles from Ru L3-edge HERFD-XAS. These observations indicated that Ru redox contributed more to discharge capacities after the first cycle. This study has pinpointed the key spectral fingerprints related to lattice oxygen redox from a molecular level and constructed a transferrable framework to rationally interpret the spectroscopic features by combining advanced experiments and theoretical calculations to design materials for Li-ion batteries and electrocatalysis applications.
Ronghui Kou - One of the best experts on this subject based on the ideXlab platform.
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Stanislaw H Nowak, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, Chengjun SunAbstract:Anion redox in lithium transition-metal oxides such as Li2RuO3 and Li2MnO3 has catalyzed intensive research efforts to find transition-metal oxides with anion redox that may boost the energy densit...
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revealing Electronic Signature of lattice oxygen redox in lithium ruthenates and implications for high energy li ion battery material designs
Chemistry of Materials, 2019Co-Authors: Pinar Karayaylali, Livia Giordano, Magali Gauthier, Wesley T Hong, Ronghui Kou, John Vinson, Thomas Kroll, Dimosthenis Sokaras, S Nowak, Chengjun SunAbstract:Anion redox in lithium transition metal oxides such as Li2RuO3 and Li2MnO3, has catalyzed intensive research efforts to find transition metal oxides with anion redox that may boost the energy density of lithium-ion batteries. The physical origin of observed anion redox remains debated, and more direct experimental evidence is needed. In this work, we have shown Electronic Signatures of oxygen-oxygen coupling, direct evidence central to lattice oxygen redox (O2-/(O2)n-), in charged Li2-xRuO3 after Ru oxidation (Ru4+/Ru5+) upon first-electron removal with lithium de-intercalation. Experimental Ru L3-edge high-energy-resolution fluorescence detected X-ray absorption spectra (HERFD-XAS), supported by ab-initio simulations, revealed that the increased intensity in the high-energy shoulder upon lithium de-intercalation resulted from increased O-O coupling, inducing (O-O) σ*-like states with π overlap with Ru d-manifolds, in agreement with O K-edge XAS spectra. Experimental and simulated O K-edge X-ray emission spectra (XES) further supported this observation with the broadening of the oxygen non-bonding feature upon charging, also originated from (O-O) σ* states. This lattice oxygen redox of Li2-xRuO3 was accompanied by a small amount of O2 evolution in the first charge from differential electrochemistry mass spectrometry (DEMS) but diminished in the subsequent cycles, in agreement with the more reduced states of Ru in later cycles from Ru L3-edge HERFD-XAS. These observations indicated that Ru redox contributed more to discharge capacities after the first cycle. This study has pinpointed the key spectral fingerprints related to lattice oxygen redox from a molecular level and constructed a transferrable framework to rationally interpret the spectroscopic features by combining advanced experiments and theoretical calculations to design materials for Li-ion batteries and electrocatalysis applications.