1. Dr. Mansour Al Hoshan TiO 2 Nanotubes Arrays fabricated by anodizing process

2. TiO 2 films have attracted attention for a great variety of applications such as: dye-sensitizing solar cells, photo catalysis, gas sensing … TiO 2 nanoporous structures are desirible for these applications due to their high surface area A number of techniques have been used to make TiO 2 films, including : Sol-gel, Chemical vapor deposition Pulsed laser deposition TiO 2 Nanotubes Arrays fabricated by anodizing process

3. DC Power supply (+) (-) e - Electrolyte (HF) AnodeCathode Ti Oxide Electrolyte Oxide Ti 4+ O 2- Ti H2OH2O H2OH2O TiO 2 Ti 4+ Ti TiO 2 Ti Tubular morphology TiO 2 barrier oxide TiO 2 Nanotubes Arrays fabricated by anodizing process

4. Top view Side view Tube wall: ~10 nm Tube hole diameter: ~100 nm Tube height : ~ 300 nm Anodizing Voltage: 20V Anodizing Time: 20 min 100 nm 10 nm ~300 nm Morphology Description Forming Conditions Void volume estimated ~ 77 % HF Solution TiO 2 Nanotubes Arrays fabricated by anodizing process

6. 2 min5 min 10 min20 min Tube size with varied anodizing time (10V) TiO 2 Nanotubes Arrays fabricated by anodizing process

7. TiO 2 nanotubes formed at 20 V for 20 min in HF solution. no heat treatment 300 o C, 3h heat treatment 700 o C, 3h heat treatment TiO 2 Nanotubes Arrays fabricated by anodizing process

8. TiO 2 Nanotubes TiO 2 Nanotubes coated with Pt or Pd TiO 2 Nanotubes Arrays fabricated by anodizing process 100 nm

9. Arrays of Aligned TiO 2 Nanotubes were formed using anodizing process Significance : - Very thin walls of nanotubes ~ 10 nm - Small tube diameter ~ 80 nm - High surface area to volume ratio Potential Application: - Gas sensor - Catalysts Support - Solar energy conversion - Photocatalyst Summary TiO 2 Nanotubes Arrays fabricated by anodizing process