Valence-to-core X-ray emission spectroscopy of vanadium oxide and lithiated vanadyl phosphate materials
| Autor: | Carrie Siu, Joshua J. Kas, M. Stanley Whittingham, Evan P. Jahrman, Gerald T. Seidler, Louis F. J. Piper, Niranjan Govind, Timothy T. Fister, William M. Holden, Jatinkumar Rana |
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| Rok vydání: | 2020 |
| Předmět: |
Valence (chemistry)
Materials science Renewable Energy Sustainability and the Environment Vanadium chemistry.chemical_element 02 engineering and technology General Chemistry Time-dependent density functional theory 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Vanadium oxide 0104 chemical sciences Delocalized electron Chemical bond chemistry Chemical physics General Materials Science Density functional theory Emission spectrum 0210 nano-technology |
| Zdroj: | Journal of Materials Chemistry A. 8:16332-16344 |
| ISSN: | 2050-7496 2050-7488 |
| Popis: | We report valence-to-core (VTC) X-ray emission spectroscopy (XES) measurements and theoretical calculations of the electrochemical sequence e-VOPO4, e-LiVOPO4, e-Li2VOPO4 and the reference oxides V2O3, VO2, and V2O5. In our analysis of these results, we establish a framework for interrogating chemical bonding that is generally applicable to a wide range of systems, including complex, extended inorganic compounds. While this latter regime has garnered less focused application than, e.g., metalloenzymes in many excellent catalysis studies, we show that the technique provides high utility in materials-focused energy storage research. Here, sensitivities to the local atomic structure and hybridization schemes are discussed in detail. Similarly, the effect of lithiation on oxidation, delocalization, and shifts in ligand valence energy levels are all readily apparent in the analyzed results. Finally, the TDDFT projections clearly reveal the directional dependencies of the valence band at each of the vanadium sites. Our results demonstrate laboratory-based X-ray spectroscopy instrumentation is a viable route for attaining well-resolved VTC-XES features for inorganic compounds of 3d transition metals, even for samples of limited quantity or suffering from sensitivity to the atmosphere. The experimental results are in good agreement with results produced by real-space Green's function and time-dependent density functional theory (TDDFT) methods, respectively. Hence, we propose that VTC-XES, when equipped with appropriate theoretical support, can be a valuable complement to X-ray absorption pre-edge features for more detailed characterization of a compound's electronic structure. We expect similar analyses will find application in a broad range of materials chemistry research and provide both fundamental and applied insights. |
| Databáze: | OpenAIRE |
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