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Characterisation of oxygen defects and nitrogen impurities in TiO2 photocatalysts using variable-temperature X-ray powder diffraction

DOI: 10.1038/s41467-021-20977-z DOI Help

Authors: Christopher Foo (University of Oxford) , Yiyang Li (University of Oxford) , Konstantin Lebedev (University of Oxford) , Tianyi Chen (University of Oxford) , Sarah Day (Diamond Light Source) , Chiu Tang (Diamond Light Source) , Chi Edman Tsang (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 12

State: Published (Approved)
Published: January 2021

Open Access Open Access

Abstract: TiO2-based powder materials have been widely studied as efficient photocatalysts for water splitting due to their low cost, photo-responsivity, earthly abundance, chemical and thermal stability, etc. In particular, the recent breakthrough of nitrogen-doped TiO2, which enhances the presence of structural defects and dopant impurities at elevated temperatures, exhibits an impressive visible-light absorption for photocatalytic activity. Although their electronic and optical properties have been extensively studied, the structure-activity relationship and photocatalytic mechanism remain ambiguous. Herein, we report an in-depth structural study of rutile, anatase and mixed phases (commercial P25) with and without nitrogen-doping by variable-temperature synchrotron X-ray powder diffraction. We report that an unusual anisotropic thermal expansion of the anatase phase can reveal the intimate relationship between sub-surface oxygen vacancies, nitrogen-doping level and photocatalytic activity. For highly doped anatase, a new cubic titanium oxynitride phase is also identified which provides important information on the fundamental shift in absorption wavelength, leading to excellent photocatalysis using visible light.

Journal Keywords: Nanoparticles; Photocatalysis; Solar fuels

Diamond Keywords: Photocatalysis

Subject Areas: Materials, Chemistry, Energy

Instruments: I11-High Resolution Powder Diffraction

Other Facilities: BL02B2 at SPring-8

Added On: 02/02/2021 09:29


Discipline Tags:

Catalysis Energy Materials Chemistry Materials Science Inorganic Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction