Synthesis and characterization of anodized titanium-oxide nanotube arrays

Anodized titanium-oxide containing highly ordered, vertically oriented TiO₂ nanotube arrays is a nanomaterial architecture that shows promise for diverse applications. In this paper, an anodization synthesis using HF-free aqueous solution is described. The anodized TiO₂ film samples (amorphous, anatase, and rutile) on titanium foils were characterized with scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Additional characterization in terms of photocurrent generated by an anode consisting of a titanium foil coated by TiO₂ nanotubes was performed using an electrochemical cell. A platinum cathode was used in the electrochemical cell. Results were analyzed in terms of the efficiency of the current generated, defined as the ratio of the difference between the electrical energy output and the electrical energy input divided by the input radiation energy, with the goal of determining which phase of TiO₂ nanotubes leads to more efficient hydrogen production. It was determined that the anatase crystalline structure converts light into current more efficiently and is therefore a better photocatalytic material for hydrogen production via photoelectrochemical splitting of water.