TiO2 nanotube arrays or nanoporous films fabricated by potentiostatic anodization of titanium (titanium alloy) in F--containing electrolytes constitute a material architecture that offers a large internal surface area and excellent electron percolation pathways for vectorial charge transfer between interfaces. The material architecture has proven to be of great interest for use in water photoelectrolysis, photocatalysis, heterojunction solar cells, and gas sensing. The parameters for TiO2 nanoporous film fabrication are found by changing the anodic oxidation voltage and phase composition of titanium alloys. When the anodization potential is below 30 V, TiO2 nanoporous film by anodizing TLM alloy aged at 550 oC for long time can be obtained.