Single-walled TiO2 Nanotubes: Enhanced Carrier-transport Properties by   TiCl4-Treatment
  In the present work we report significant enhancement of the photoelectrochemical properties of self-organized TiO2 nanotubes by a combined de-coring of classic nanotubes followed by an appropiate TiCl4-treatment. We show that, except for the expected particle decoration, a key effect of the TiCl4 treatment is that the electron transport characteristics in TiO2 nanotubes can be drastically improved, e.g. we observe an enhancement of up to 70 % in electron transport times. 
Imgon Hwang, Seulgi So, Mohamed Mokhtar, Abdelmohsen Alshehri, Shaeel   A. Al-Thabaiti, Anca Mazare, and Patrik Schmuki
cond-mat.mtrl-sci