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Distinct behavior of localized and delocalized carriers in anatase TiO2 (001) during reaction with O-2

Bigi, C; Tang, Z; Pierantozzi, GM; Orgiani, P; Das, PK; Fujii, J; Vobornik, I; ... Selloni, A; + view all (2020) Distinct behavior of localized and delocalized carriers in anatase TiO2 (001) during reaction with O-2. Physical Review Materials , 4 (2) , Article 025801. 10.1103/PhysRevMaterials.4.025801. Green open access

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Abstract

Two-dimensional (2D) metallic states induced by oxygen vacancies ( V O s ) 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 V O -induced states at the (001) surface of anatase TiO 2 , 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 O 2 : while IGs are almost completely quenched, the metallic states are only weakly affected. DFT calculations indeed show that the IGs originate from surface V O s and remain localized at the surface, where they can promptly react with O 2 . In contrast, the metallic states originate from subsurface vacancies whose migration to the surface for recombination with O 2 is kinetically hindered on anatase TiO 2 (001), thus making them much less sensitive to oxygen dosing.

Type: Article
Title: Distinct behavior of localized and delocalized carriers in anatase TiO2 (001) during reaction with O-2
Open access status: An open access version is available from UCL Discovery
DOI: 10.1103/PhysRevMaterials.4.025801
Publisher version: https://doi.org/10.1103/PhysRevMaterials.4.025801
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10093370
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