Indium Doped TiO2 Photocatalysts with High Temperature Anatase Stability

Vignesh Kumaravel, Stephen Rhatigan, Snehamol Mathew, John Bartlett, Michael Nolan, Steven Hinder, Preetam Sharma, Anukriti Singh, John Byrne, John Harrison, Suresh C. Pillai

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Abstract

The thermal stability of anatase titanium dioxide (TiO 2) is a prerequisite to fabricate photocatalyst-coated indoor building materials for use in antimicrobial and self-cleaning applications under normal room light illumination. Metal doping of TiO 2 is an appropriate way to control the anatase to rutile phase transition (ART) at high processing temperatures. In this work, ART of indium (In)-doped TiO 2 (In-TiO 2) was investigated in detail in the range of 500-900 °C. In-TiO 2 (In mol % = 0-16) was synthesized via a modified sol-gel approach. These nanoparticles were further characterized by means of powder X-ray diffraction (XRD), Raman, photoluminescence (PL), transient photocurrent response, and X-ray photoelectron spectroscopy (XPS) techniques. XRD results showed that the anatase phase was maintained up to 64% by 16 mol % of In doping at 800 °C of calcination temperature. XPS results revealed that the binding energies of Ti 4+ (Ti 2p 1/2 and Ti 2p 3/2) were red-shifted by In doping. The influence of In doping on the electronic structure and oxygen vacancy formation of anatase TiO 2 was studied using density functional theory corrected for on-site Coulomb interactions (DFT+U). First-principles results showed that the charge-compensating oxygen vacancies form spontaneously at sites adjacent to the In dopant. DFT+U calculations revealed the formation of In - 5s states in the band gap of the anatase host. The formation of In 2O 3 at the anatase surface was also examined using a slab model of the anatase (101) surface modified with a nanocluster of composition In 4O 6. The formation of a reducing oxygen vacancy also has a moderate energy cost and results in charge localization at In ions of the supported nanocluster. PL and photocurrent measurements suggested that the charge carrier recombination process in TiO 2 was reduced in the presence of In dopant. The photocatalytic activity of 2% In-TiO 2 calcined at 700 °C is more comparable with that of pure anatase.

Original languageEnglish
Pages (from-to)21083-21096
Number of pages14
JournalThe Journal of Physical Chemistry C
Volume123
Issue number34
Early online date5 Aug 2019
DOIs
Publication statusPublished - 29 Aug 2019

Keywords

  • Photocatalysis
  • Nanomaterials
  • Titania
  • Dopant
  • Phase stability

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    Kumaravel, V., Rhatigan, S., Mathew, S., Bartlett, J., Nolan, M., Hinder, S., Sharma, P., Singh, A., Byrne, J., Harrison, J., & Pillai, S. C. (2019). Indium Doped TiO2 Photocatalysts with High Temperature Anatase Stability. The Journal of Physical Chemistry C, 123(34), 21083-21096. https://doi.org/10.1021/acs.jpcc.9b06811