Electron spin resonance from annealed titania nanotubes |
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| Authors: | JM Cho WJ Yun J-K Lee HS Lee WW So SJ Moon Y Jia H Kulkarni Y Wu |
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| Institution: | (1) Department of Physics, Chonbuk National University, Jeonju, 561-756, Korea;(2) Research Institute of Physics and Chemistry, Chonbuk National University, Jeonju, 561-756, Korea;(3) Jeonju Center of Korea Basic Science Institute, Jeonju, 561-756, Korea;(4) Advanced Chemical Technology Division, Korea Research Institute of Chemical Technology, Daejeon, 305-343, Korea;(5) Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA |
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| Abstract: | Titania nanotubes were prepared using a hydrothermal method. Hydrogen titanate nanotubes (H-TNTs) with an anatase phase changed
to anatase nanocrystals at about 500 °C, and then a rutile structure at ∼800 °C. A sharp and symmetrical electron spin resonance
(ESR) signal (g=2.003), attributed to a single-electron-trapped oxygen-vacancy (SETOV), was obtained at the annealed H-TNTs
(T<500 °C). The SETOV signal increased and maximized remarkably at about 400–500 °C. Then, the nanotube structure appeared
to be demolished. Yet, when the vacuum-heated H-TNTs were sealed in N2 or Ar ambient, some additional ESR signals appeared besides the SETOV signal. The broad asymmetric ESR signal (g=1.98) was
attributed to a surface oxygen vacancy related to the Ti3+ sites in a reduced TiO2 matrix. The vacuum-heated sodium titanate nanotubes (Na-TNTs) showed only the SETOV signal (T<500 °C).
PACS 61.46.Fg; 61.72.Ji; 76.30.-v |
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