Room Temperature One-Step Polyol Synthesis of Anatase TiO2 Nanotube Arrays: Photoelectrochemical Properties

We describe an optimized anodization process to fabricate anatase TiO2 nanotube arrays at room temperature using a polyol electrolyte. The critical roles of water and anodization voltage are investigated, and mechanistic actions are considered. The as-fabricated electrodes show low efficiency when used as photoanodes to photoelectrochemically split water; however, their efficiency is remarkably enhanced upon their annealing at temperatures as low as 300 degrees C. The efficiency of the annealed samples was found to increase with the anatase content in the as-anodized electrodes, suggesting that these pre-existing crystallites can act as seeding layers that enhance the nucleation and growth of further anatase crystallites.