Strong Visible Absorption and Photoluminescence of Titanic Acid   Nanotubes by Hydrothermal Method
  Titanic acid nanotubes (with a chemical formula H2Ti2O4(OH)2, abbreviated as TANTs) were synthesized by the hydrothermal method using commercial TiO2 nanoparticle powder (P25, Degussa, Germany) including anatase and rutile phase as a starting material. Conversion from nanoparticles to nanotubes was achieved by treating the nanoparticle powder with 10 M NaOH aqueous solution. Absorption and photoluminescence (PL) data indicate that the nanotubes obtained under slow and suitable drying and heating conditions had very strong and stable visible absorption with three peaks at 515, 575, and 675 nm and photoluminescence at room temperature in air. 
Baoli Tian, Xing Zhang, Shuxi Dai, Ke Cheng, Zhensheng Jin, Yabin   Huang, Zuliang Du, Guangtian Zou, Bingsuo Zou
cond-mat.mtrl-sci cond-mat.mes-hall