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Marginally Hydrogenated Triphasic Titania Nanotubes for Effective Visible‐Light Photocatalytic Hydrogen Generation
Author(s) -
Preethi Laguduva K.,
Mathews Tom,
Walczak Lukasz,
Gopinath Chinnakonda S.
Publication year - 2018
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201700406
Subject(s) - photocatalysis , brookite , materials science , anatase , hydrogen , rutile , visible spectrum , chemical engineering , annealing (glass) , hydrogen production , nanotechnology , water splitting , photochemistry , catalysis , chemistry , optoelectronics , organic chemistry , composite material , engineering
We report the first demonstration of hydrogen‐annealed triphase TiO 2 nanotubes (anatase–rutile–brookite) (T‐ARB) as a visible‐light‐active photocatalyst for water splitting with high quantum efficiency. As‐synthesized T‐ARB was annealed under hydrogen atmosphere at 250 and 450 °C for 2 h. We found that the tubular structures were retained in the hydrogenated TiO 2 samples. It was observed that the concentrations of Ti 3+ and the oxygen vacancies and their distribution significantly increased with respect to the hydrogen annealing temperature. Such changes in defects were found to be critical in enhancing the photocatalytic activity of the hydrogen‐annealed triphase TiO 2 nanotubes. The triphase TiO 2 nanotubes hydrogen annealed at 450 °C were 16 times more efficient than pristine TiO 2 . Such an increase in the photocatalytic activity was explained by a triphase band diagram with defect states below the conduction band of each phase, which facilitated visible‐light activity and easy transfer of charge carriers from one phase to another. Our study showed that the well‐designed multiphase construction with oxygen vacancies enhanced the photocatalytic activity tremendously owing to the presence of a higher number of phase junctions.