An innovative method to quickly and simply prepare TiO2 nanorod arrays and improve their performance in photo water splitting

• TiO2 nanorod arrays were fast fabricated by solution growth at 65 °C in atmosphere.
• The prepared TiO2 nanorods were 20–180 nm in diameter and composed of rutile phase.
• TiO2 nanorod arrays calcined at 550 °C exhibited the best photoconversion efficiency.
• This TiO2 nanorod array had a higher photocurrent than compact nanoparticle film.
• Nyquist plot demonstrated that oriented nanorod array could assist electron transfer.

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 TiCl4 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 °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%.

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