02124nas a2200181   4500008004100000245010700041210006900148260000800217300002600225490000600251520144700257100002001704700002301724700001701747700002001764700003001784856012801814       2017                        eng d00aStudy on doped heterojunctions in TiO2 nanotubes: an efficient photocatalyst for solar water splitting0 aStudy on doped heterojunctions in TiO2 nanotubes an efficient ph  cOCT  aArticle Number: 143140 v73 aThe two important factors that affect sunlight assisted water splitting ability of TiO2 are its charge recombination and large band gap. We report the first demonstration of nitrogen doped triphase (anatase-rutile-brookite) TiO2 nanotubes as sun light active photocatalyst for water splitting with high quantum efficiency. Nitrogen doped triphase TiO2 nanotubes, corresponding to different nitrogen concentrations, are synthesized electrochemically. Increase in nitrogen concentration in triphase TiO2 nanotubes is found to induce brookite to anatase phase transformation. The variation in density of intra-band states (Ti3+ and N 2p states) with increase in nitrogen doping are found to be critical in tuning the photocatalytic activity of TiO2 nanotubes. The presence of bulk heterojunctions in single nanotube of different nitrogen doped TiO2 samples is confirmed from HRTEM analysis. The most active nitrogen doped triphase TiO2 nanotubes are found to be 12 times efficient compared to pristine triphase TiO2, for solar hydrogen generation. The band alignment and charge transfer pathways in nitrogen doped TiO2 with triphase heterojunctions are delineated. Bulk heterojunctions among the three phases present in the nanotubes with intra-band defect states is shown to enhance the photocatalytic activity tremendously. Our study also confirms the theory that three phase system is efficient in photocatalysis compared to two phase system.1 aPreethi, L., K.1 aAntony, Rajini, P.1 aMathews, Tom1 aWalczak, Lukasz1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/study-doped-heterojunctions-tio2-nanotubes-efficient-photocatalyst-solar-water-splitting02085nas a2200241   4500008004100000022001400041245011900055210006900174260000800243300001200251490000600263520126900269653002001538653001201558653001801570653001201588653002001600100002601620700001701646700002001663700003001683856013001713       2018                        eng d  a2194-428800aMarginally hydrogenated triphasic titania nanotubes for effective visible-light photocatalytic hydrogen generation0 aMarginally hydrogenated triphasic titania nanotubes for effectiv  cFEB  a280-2880 v63 a<p>We report the first demonstration of hydrogen-annealed triphase TiO 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 4508 degrees C for 2 h. We found that the tubular structures were retained in the hydrogenated TiO2 samples. It was observed that the concentrations of Ti3+ 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 TiO2 nanotubes. The triphase TiO2 nanotubes hydrogen annealed at 450 degrees C were 16 times more efficient than pristine TiO2. 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.</p>10acharge transfer10aDefects10aHydrogenation10atitania10awater splitting1 aPreethi, Laguduva, K.1 aMathews, Tom1 aWalczak, Lukasz1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/marginally-hydrogenated-triphasic-titania-nanotubes-effective-visible-light-photocatalytic