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  4. Hydrogen treated anatase TiO2: A new experimental approach and further insights from theory
 
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2016
Journal Article
Title

Hydrogen treated anatase TiO2: A new experimental approach and further insights from theory

Abstract
Hydrogenated TiO2 (H:TiO2) is intensively investigated due to its improvement in solar absorption, but there are major issues related to its structural, optical and electronic properties and therefore an easily compatible method of preparation is much needed. In order to clarify this issue we studied TiO2 nanocrystals under the partial pressure of hydrogen to modify the structural, optical and electrical properties and to significantly improve the photocatalytic and photoelectrochemical performance. The hydrogen treated TiO2 nanocrystals contained paramagnetic Ti3+ centers and exhibited a higher visible light absorption cross-section as was confirmed by electron paramagnetic resonance diffuse reflectance spectra measurements and X-ray photoelectron spectroscopy. The hydrogen annealed samples showed a noticeable improvement in photocatalytic activity under visible light (lambda > 380 nm) which was demonstrated by the degradation of methylene blue dye and an improved photoelectrochemical response in terms of high photocurrent density. Ab initio simulations of TiO2 were performed in order to elucidate the conditions under which localized Ti3+ centres rather than delocalized shallow donor states are created upon the reduction of TiO2. Randomly distributed oxygen vacancies lead to localized deep donor states while the occupation of the oxygen vacancies by atomic hydrogen favours the delocalized shallow donor solution. Furthermore, it was found that localization is stabilized at high defect concentrations and destabilized under external pressures. In those cases where localized Ti3+ states are present, the DFT simulations showed a considerable enhancement of the visible light absorption as well as a pronounced broadening of the localized Ti3+ energy levels with increasing defect concentration.
Author(s)
Mehta, Manan
Department of Chemical Engineering, Indian Institute of Technology, HauzKhas, New Delhi
Kodan, Nishan
Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi-
Kumar, Sandeeep
epartment of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi
Kaushal, Akshex
Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi
Mayrhofer, Leonhard
Fraunhofer-Institut für Werkstoffmechanik IWM  
Walter, Michael  
Fraunhofer-Institut für Werkstoffmechanik IWM  
Moseler, Michael  
Fraunhofer-Institut für Werkstoffmechanik IWM  
Dey, Avishek
Department of Engineering and Innovation, The Open University, Milton Keynes, UK
Krishnamurthy , Satheesh
Department of Engineering and Innovation, The Open University, Milton Keynes, UK
Basu, Suddhasatwa
Department of Chemical Engineering, Indian Institute of Technology, HauzKhas, New Delhi
Singh, Aadesh P.
Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi
Journal
Journal of materials chemistry. A, Materials for energy and sustainability  
Project(s)
SOLAROGENIX  
Funder
European Commission  
Open Access
Link
Link
DOI
10.1039/c5ta07133j
Additional full text version
Landing Page
Language
English
Fraunhofer-Institut für Werkstoffmechanik IWM  
Keyword(s)
  • titanium dioxide

  • visible light

  • surface

  • photocatalysis

  • nanoparticles

  • spectroscopy

  • oxidation

  • H-1-NMR

  • metal

  • oxide

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