The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study
We report a combined non-local (PBE-TC-LRC) Density Functional Theory (DFT) and linear-response time-dependent DFT (LR-TDDFT) study of the structural, electronic, and optical properties of the cation-vacancy based defects in aluminosilicate (AlSi) imogolite nanotubes (Imo-NTs) that have been recentl...
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Frontiers Media S.A.
2019-04-01
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| Series: | Frontiers in Chemistry |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fchem.2019.00210/full |
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| author | Emiliano Poli Joshua D. Elliott Joshua D. Elliott Joshua D. Elliott Sergey K. Chulkov Matthew B. Watkins Gilberto Teobaldi Gilberto Teobaldi Gilberto Teobaldi |
| author_facet | Emiliano Poli Joshua D. Elliott Joshua D. Elliott Joshua D. Elliott Sergey K. Chulkov Matthew B. Watkins Gilberto Teobaldi Gilberto Teobaldi Gilberto Teobaldi |
| author_sort | Emiliano Poli |
| collection | DOAJ |
| description | We report a combined non-local (PBE-TC-LRC) Density Functional Theory (DFT) and linear-response time-dependent DFT (LR-TDDFT) study of the structural, electronic, and optical properties of the cation-vacancy based defects in aluminosilicate (AlSi) imogolite nanotubes (Imo-NTs) that have been recently proposed on the basis of Nuclear Magnetic Resonance (NMR) experiments. Following numerical determination of the smallest AlSi Imo-NT model capable of accommodating the defect-induced relaxation with negligible finite-size errors, we analyse the defect-induced structural deformations in the NTs and ensuing changes in the NTs' electronic structure. The NMR-derived defects are found to introduce both shallow and deep occupied states in the pristine NTs' band gap (BG). These BG states are found to be highly localized at the defect site. No empty defect-state is modeled for any of the considered systems. LR-TDDFT simulation of the defects reveal increased low-energy optical absorbance for all but one defects, with the appearance of optically active excitations at energies lower than for the defect-free NT. These results enable interpretation of the low-energy tail in the experimental UV-vis spectra for AlSi NTs as being due to the defects. Finally, the PBE-TC-LRC-approximated exciton binding energy for the defects' optical transitions is found to be substantially lower (up to 0.8 eV) than for the pristine defect-free NT's excitations (1.1 eV). |
| first_indexed | 2024-12-12T14:40:36Z |
| format | Article |
| id | doaj.art-22d8bcb3a4ad47e2abd5f4ea5f972d44 |
| institution | Directory Open Access Journal |
| issn | 2296-2646 |
| language | English |
| last_indexed | 2024-12-12T14:40:36Z |
| publishDate | 2019-04-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Chemistry |
| spelling | doaj.art-22d8bcb3a4ad47e2abd5f4ea5f972d442022-12-22T00:21:15ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462019-04-01710.3389/fchem.2019.00210437025The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT StudyEmiliano Poli0Joshua D. Elliott1Joshua D. Elliott2Joshua D. Elliott3Sergey K. Chulkov4Matthew B. Watkins5Gilberto Teobaldi6Gilberto Teobaldi7Gilberto Teobaldi8The Abdus Salam Center for Theoretical Physics, Condensed Matter and Statistical Physics Department, Trieste, ItalyDipartimento di Fisica e Astronomia “Galileo Galilei”, Università degli Studi di Padova, Padova, ItalyCNR-IOM DEMOCRITOS, Consiglio Nazionale delle Ricerche-Istituto Officina dei Materiali, Trieste, ItalySchool of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, United KingdomSchool of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln, United KingdomSchool of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln, United KingdomDaresbury Laboratory, Scientific Computing Department, Science and Technology Facilities Council, Warrington, United KingdomBeijing Computational Science Research Centre, Beijing, ChinaStephenson Institute for Renewable Energy and Department of Chemistry, University of Liverpool, Liverpool, United KingdomWe report a combined non-local (PBE-TC-LRC) Density Functional Theory (DFT) and linear-response time-dependent DFT (LR-TDDFT) study of the structural, electronic, and optical properties of the cation-vacancy based defects in aluminosilicate (AlSi) imogolite nanotubes (Imo-NTs) that have been recently proposed on the basis of Nuclear Magnetic Resonance (NMR) experiments. Following numerical determination of the smallest AlSi Imo-NT model capable of accommodating the defect-induced relaxation with negligible finite-size errors, we analyse the defect-induced structural deformations in the NTs and ensuing changes in the NTs' electronic structure. The NMR-derived defects are found to introduce both shallow and deep occupied states in the pristine NTs' band gap (BG). These BG states are found to be highly localized at the defect site. No empty defect-state is modeled for any of the considered systems. LR-TDDFT simulation of the defects reveal increased low-energy optical absorbance for all but one defects, with the appearance of optically active excitations at energies lower than for the defect-free NT. These results enable interpretation of the low-energy tail in the experimental UV-vis spectra for AlSi NTs as being due to the defects. Finally, the PBE-TC-LRC-approximated exciton binding energy for the defects' optical transitions is found to be substantially lower (up to 0.8 eV) than for the pristine defect-free NT's excitations (1.1 eV).https://www.frontiersin.org/article/10.3389/fchem.2019.00210/fullinorganic nanotubesimogolite nanotubesdefectsDFTTD-DFToptical properties |
| spellingShingle | Emiliano Poli Joshua D. Elliott Joshua D. Elliott Joshua D. Elliott Sergey K. Chulkov Matthew B. Watkins Gilberto Teobaldi Gilberto Teobaldi Gilberto Teobaldi The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study Frontiers in Chemistry inorganic nanotubes imogolite nanotubes defects DFT TD-DFT optical properties |
| title | The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study |
| title_full | The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study |
| title_fullStr | The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study |
| title_full_unstemmed | The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study |
| title_short | The Role of Cation-Vacancies for the Electronic and Optical Properties of Aluminosilicate Imogolite Nanotubes: A Non-local, Linear-Response TDDFT Study |
| title_sort | role of cation vacancies for the electronic and optical properties of aluminosilicate imogolite nanotubes a non local linear response tddft study |
| topic | inorganic nanotubes imogolite nanotubes defects DFT TD-DFT optical properties |
| url | https://www.frontiersin.org/article/10.3389/fchem.2019.00210/full |
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