Tuning the Electronic Structure of Anatase Through Fluorination

Abstract

A highly fluorinated anatase lattice has been recently reported, providing a new class of materials whose general chemical formula is $\mathrm{T}{\mathrm{i}}_{1-x}{\square }_x{\mathrm{X}}_{4x}{\mathrm{O}}_{2-4x}$ (X${}^{-}$ = F${}^{-}$ or OH${}^{-}$). To characterise the complex structural features of the material and the different F environments, we here apply a computational screening procedure. After deriving a polarisable force--field from DFT simulations, we screen in a step-wise fashion a large number of possible configurations differing in the positioning of the titanium vacancies ($\square$) and of the fluorine atoms. At each step only 10% of the configurations are retained. At the end of the screening procedure, a configuration is selected and simulated using DFT-based molecular dynamics. This allows us to analyse the atomic structure of the material, which is strongly disordered, leading to a strong decrease (by 0.8~eV) of the band gap compared to conventional anatase.

13 pages, 5 figures, 5 supplementary figures, 2 supplementary tables. Updated version. Accepted for publication in Scientific Reports

References in corpus (2)

• Including many-body effects in models for ionic liquids
• A transferable ab-initio based force field for aqueous ions

Cited by in corpus (1)

• Photocatalytic Behavior of Fluorinated Rutile TiO${}_2$(110) Surface: Understanding from the Band Model