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Theoretical studies on electronic structure and x-ray spectroscopies of 2D materials
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. (Prof. Yi Luo)ORCID-id: 0000-0001-6508-8355
2016 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Extraordinary chemical and physical properties have been discovered from the studies of two-dimensional (2D) materials, ever since the successful exfoliation of graphene, the first 2D material. Theoretical investigations of electronic structure and spectroscopies of these materials play a fundamental role in deep understanding the various properties. In particular, the band structure and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy can provide critical information near the Fermi level. In this thesis, we performed first-principles density functional theory calculations to study the electronic structure and NEXAFS spectra of four materials, including three 2D materials and one bulk material. The three 2D materials are atomically thin bismuth telluride, nitrogen and boron nitride doped graphenes. The bulk material is lithium intercalated graphite, an analogue of lithium doped graphene. Our studies provide important electronic property information of the studied materials, and are helpful for understanding their properties and developing potential applications.

Ort, förlag, år, upplaga, sidor
KTH Royal Institute of Technology, 2016. , s. 79
Serie
TRITA-BIO-Report, ISSN 1654-2312 ; 2016:6
Nationell ämneskategori
Teoretisk kemi
Forskningsämne
Teoretisk kemi och biologi
Identifikatorer
URN: urn:nbn:se:kth:diva-185683ISBN: 978-91-7595-948-1 (tryckt)OAI: oai:DiVA.org:kth-185683DiVA, id: diva2:922974
Disputation
2016-05-19, FB42, AlbaNova University Center, Roslagstullsbacken 21, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20160425

Tillgänglig från: 2016-04-25 Skapad: 2016-04-25 Senast uppdaterad: 2022-06-22Bibliografiskt granskad
Delarbeten
1. Electronic structure of bismuth telluride quasi-two-dimensional crystal: A first principles study
Öppna denna publikation i ny flik eller fönster >>Electronic structure of bismuth telluride quasi-two-dimensional crystal: A first principles study
2011 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 8, s. 083113-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The electronic structures of atomically thin layers of bismuth telluride (Bi2Ti3) have been studied by using density functional theory. It is found that quintuple layers of Bi2Te3 are semiconductor with localized shallow bands. The weak covalent Bi-Te-2 interaction in quintuple layer allows to further exfoliate it to form bilayer and trilayer sheets. In the latter cases, the valence electrons cannot fully occupy all the valence bands and the sheets become metallic.

Nyckelord
TOTAL-ENERGY CALCULATIONS, WAVE BASIS-SET, TOPOLOGICAL INSULATORS, THERMOELECTRIC FIGURE, QUANTUM, SURFACE, BI2TE3, MERIT
Nationell ämneskategori
Fysik
Identifikatorer
urn:nbn:se:kth:diva-31379 (URN)10.1063/1.3556654 (DOI)000287764300077 ()2-s2.0-79952094720 (Scopus ID)
Anmärkning
QC 20110315Tillgänglig från: 2011-03-15 Skapad: 2011-03-14 Senast uppdaterad: 2022-06-24Bibliografiskt granskad
2. Electronic Structure of Nitrogen-Doped Graphene in the Ground and Core-Excited States from First-Principles Simulations
Öppna denna publikation i ny flik eller fönster >>Electronic Structure of Nitrogen-Doped Graphene in the Ground and Core-Excited States from First-Principles Simulations
2015 (Engelska)Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, nr 29, s. 16660-16666Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We have calculated the N 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of nitrogen-doped monolayer graphene (NG) using density functional theory (DFT) with the equivalent core hole approximation. The hexavacancy (6V) defect and its dependence on the nitrogen-doping concentration have been analyzed in detail via both N 1s -> pi* and N 1s -> sigma* transitions. The NEXAFS spectra are sensitive to the doping concentration of N in the pi* region: diluted doping weakens the main pi* peak and smears the oscillations in this region. The vacancy defect leads to a red-shift in both the pi and sigma spectra. A pyridinic nitrogen at the 6V defect center exhibits a sharp pi* peak at 398.4 eV, which agrees well with the experimental pre-edge structure at 398.6 eV. The sigma* peak is split in two, which can serve as the fingerprint to reveal the nature of the defect. A structural change from pyridinic to pyrrolic NG results in a distinctive difference in the spectral shape. The ground-state band structure has also been simulated at the DFT level with periodic boundary conditions. Similar profiles are found in the N 2p projected density of states above the Fermi level and in the N 1s NEXAFS spectra.

Nationell ämneskategori
Kemi
Identifikatorer
urn:nbn:se:kth:diva-172714 (URN)10.1021/acs.jpcc.5b03981 (DOI)000358624000029 ()2-s2.0-84937900185 (Scopus ID)
Anmärkning

QC 20150831

Tillgänglig från: 2015-08-31 Skapad: 2015-08-27 Senast uppdaterad: 2022-06-23Bibliografiskt granskad
3. Dopant Size Dependent Electronic Structure of Boron Nitride-Doped Graphene
Öppna denna publikation i ny flik eller fönster >>Dopant Size Dependent Electronic Structure of Boron Nitride-Doped Graphene
Visa övriga...
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Teoretisk kemi
Identifikatorer
urn:nbn:se:kth:diva-185705 (URN)
Anmärkning

Qc 20160425

Tillgänglig från: 2016-04-25 Skapad: 2016-04-25 Senast uppdaterad: 2022-06-22Bibliografiskt granskad
4. Electronic Structure of Lithium Intercalated Graphite from First-Principles Simulations
Öppna denna publikation i ny flik eller fönster >>Electronic Structure of Lithium Intercalated Graphite from First-Principles Simulations
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Teoretisk kemi
Identifikatorer
urn:nbn:se:kth:diva-185708 (URN)
Anmärkning

QC 20160425

Tillgänglig från: 2016-04-25 Skapad: 2016-04-25 Senast uppdaterad: 2022-06-22Bibliografiskt granskad

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