A Study on Doped Heterojunctions in TiO 2 Nanotubes: An Efficient Photocatalyst for Solar Water Splitting.

Autor: Preethi LK; Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam, 603 102, India. preaag@gmail.com., Antony RP; Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Mumbai, 400 085, India., Mathews T; Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam, 603 102, India. tom@igcar.gov.in., Walczak L; PREVAC sp. z o.o., Raciborska 61, 44-362, Rogow, Poland., Gopinath CS; Catalysis Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411 008, India.
Jazyk: angličtina
Zdroj: Scientific reports [Sci Rep] 2017 Oct 30; Vol. 7 (1), pp. 14314. Date of Electronic Publication: 2017 Oct 30.
DOI: 10.1038/s41598-017-14463-0
Abstrakt: The two important factors that affect sunlight assisted water splitting ability of TiO 2 are its charge recombination and large band gap. We report the first demonstration of nitrogen doped triphase (anatase-rutile-brookite) TiO 2 nanotubes as sun light active photocatalyst for water splitting with high quantum efficiency. Nitrogen doped triphase TiO 2 nanotubes, corresponding to different nitrogen concentrations, are synthesized electrochemically. Increase in nitrogen concentration in triphase TiO 2 nanotubes is found to induce brookite to anatase phase transformation. The variation in density of intra-band states (Ti 3+ and N 2p states) with increase in nitrogen doping are found to be critical in tuning the photocatalytic activity of TiO 2 nanotubes. The presence of bulk heterojunctions in single nanotube of different nitrogen doped TiO 2 samples is confirmed from HRTEM analysis. The most active nitrogen doped triphase TiO 2 nanotubes are found to be 12 times efficient compared to pristine triphase TiO 2 , for solar hydrogen generation. The band alignment and charge transfer pathways in nitrogen doped TiO 2 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.
Databáze: MEDLINE
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