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Distinct behavior of localized and delocalized carriers in anatase TiO2 (001) during reaction with O2

DOI: 10.1103/PhysRevMaterials.4.025801 DOI Help

Authors: Chiara Bigi (Istituto Officina dei Materiali (IOM)-CNR; University of Milano) , Zhenkun Tang (Princeton University; Hengyang Normal University) , Gian Marco Pierantozzi (Istituto Officina dei Materiali (IOM)-CNR) , Pasquale Orgiani (Istituto Officina dei Materiali (IOM)-CNR; CNR-SPIN) , Pranab Kumar Das (Istituto Officina dei Materiali (IOM)-CNR; International Centre for Theoretical Physics (ICTP)) , Jun Fujii (Istituto Officina dei Materiali (IOM)-CNR) , Ivana Vobornik (Istituto Officina dei Materiali (IOM)-CNR) , Tommaso Pincelli (Istituto Officina dei Materiali (IOM)-CNR) , Alessandro Troglia (Istituto Officina dei Materiali (IOM)-CNR; University of Milano) , Tien-lin Lee (Diamond Light Source) , Regina Ciancio (Istituto Officina dei Materiali (IOM)-CNR) , Goran Drazic (National Institute of Chemistry, Slovenia) , Alberto Verdini (Istituto Officina dei Materiali (IOM)-CNR) , Anna Regoutz (Imperial College London) , Phil D. C. King (University of St. Andrews) , Deepnarayan Biswas (University of St. Andrews) , Giorgio Rossi (Istituto Officina dei Materiali (IOM)-CNR; University of Milano) , Giancarlo Panaccione (Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC) , Annabella Selloni (Princeton University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Materials , VOL 4

State: Published (Approved)
Published: February 2020
Diamond Proposal Number(s): 16041

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.

Journal Keywords: Electronic structure; Surface & interfacial phenomena; Physical Systems; 2-dimensional systems; Thin films; Transition-metal oxides; Density functional theory; Photoemission spectroscopy

Subject Areas: Materials, Physics


Instruments: I09-Surface and Interface Structural Analysis