Distinct behaviour of localized and delocalized carriers in anatase TiO2 (001) during reaction with O2
Abstract
Two-dimensional (2D) metallic states induced by oxygen vacancies (VOs) at oxide surfaces and interfaces provide opportunities for the development of advanced applications, but the ability to control the behavior of these states is still limited. We used angle resolved photoelectron spectroscopy combined with density-functional theory (DFT) to study the reactivity of VO-induced states at the (001) surface of anatase TiO2, where both 2D metallic and deeper lying in-gap states (IGs) are observed. The 2D and IG states exhibit remarkably different evolutions when the surface is exposed to molecular O2: while IGs are almost completely quenched, the metallic states are only weakly affected. DFT calculations indeed show that the IGs originate from surface VOs and remain localized at the surface, where they can promptly react with O2. In contrast, the metallic states originate from subsurface vacancies whose migration to the surface for recombination with O2 is kinetically hindered on anatase TiO2 (001), thus making them much less sensitive to oxygen dosing.
Citation
Bigi , C , Tang , Z , Pierantozzi , G , Orgiani , P , Das , P , Fujii , J , Vobornik , I , Pincelli , T , Troglia , A , Lee , T , Ciancio , R , Drazic , G , Verdini , A , Regoutz , A , King , P , Biswas , D , Rossi , G , Panaccione , G & Selloni , A 2020 , ' Distinct behaviour of localized and delocalized carriers in anatase TiO 2 (001) during reaction with O 2 ' , Physical Review Materials , vol. 4 , no. 2 , 025801 . https://doi.org/10.1103/PhysRevMaterials.4.025801
Publication
Physical Review Materials
Status
Peer reviewed
ISSN
2475-9953Type
Journal article
Rights
Copyright © 2020 American Physical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1103/PhysRevMaterials.4.025801
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