We developed a simple way to synthesize TiO2 nanorod array on a Ti foil under moderate conditions in an ambient atmosphere. The morphology of the TiO2 nanostructure synthesized by titanium salts and acids depends on the type of acid and Ti precursors. The growth of rutile TiO2 nanorods with a diameter of 20-180 nm on a Ti foil was obtained when Ti foil was treated in the presence of TiCI4 and HNO3. The diameters and growth rates of TiO2 nanorods increased with increasing concentrations of HNO3 and Ti precursor. As a consequence, these factors can easily be tuned to generate the desired TiO2 nanorod array in this proposed process. By calcining at a temperature of 550 degrees C, the TiO2 nanorod arrays exhibited optimal photocatalytic activity due to an oriented nanorod structure and good crystallinity. The photoconversion efficiency is a function of array thickness and nanorod morphology. Due to an oriented nanorod structure beneficial to electron transfer, the TiO2 nanorod array has a maximum photoconversion efficiency of 8.65% higher than that of the compact nanoparticle film of 2.33%. (C) 2014 Elsevier B.V. All rights reserved.