Comparison of Photoelectrochemical Current in Amorphous and Crystalline Anodized TiO₂ Nanotube Electrodes

Abstract

The interest in TiO2 nanotubes has resulted in a lot of studies including the effects of various parameters on the properties and performance for different applications. This study investigated the effect of anodization at a low temperature on the properties and photoelectrochemical performance. The effects of varied anodization settings on morphology, crystallinity, and PEC response were studied. Low-temperature anodization resulted in smaller pore diameter and shorter tube length. Annealing temperature affected the presence of varied phases of TiO2 such as the prominence of anatase and amounts of rutile and amorphous TiO2 at 125°C. To observe photoelectrochemical response, annealing at 450°C is necessary. However, a cathodic response was observed for TiO2 nanotubes synthesized with low voltage at low temperature. Hence, amorphous titania nanotubes annealed at 125°C with thickness achieved in the anodization can be a potential material used for photocatalytic applications due to its determined cathodic photoelectrochemical response.

Direct Conversion of Aluminum Wires into Phase-Controllable Aluminum Oxide Nanoparticles by Anodization for Chromium Adsorption

“…The cathodic reduction reaction occurs simultaneously with the anodic oxidation process described earlier. Electrolysis of water and field-assisted deprotonation of hydroxyl ions produce oxygen species, and hydrogen gas is formed at the cathode via the following reactions. ,− …”

Investigation of photoelectrochemical properties of TiO2 nanotube arrays prepared by anodization method

“…[4] Therefore, TiO2 ought to have high surface area in contact with electrolyte such as nanotubes (NTs), nanowires and nanorods, etc. Nanotube arrays would have both large surface area and better transport property due to it's relatively short conduction path, [5] thus, it was focused to synthesize by many methods such as anodization, [6] template method, [7] hydrothermal method. [8] Anodic oxidation was one of the mentioned above methods which was low-cost electrochemical process and produced ordered oxide NTs or pore structures on Ti substrate.…”

“…[8] Anodic oxidation was one of the mentioned above methods which was low-cost electrochemical process and produced ordered oxide NTs or pore structures on Ti substrate. [6] After anodization the structure of TiO2 was amorphous and it can be converted to crystalline structure by annealing process. There are three main phases (anatase, rutile and brookite), among them brookite hasn't photoreactivity due to its metastable structure, while anatase has higher photoelectrochemical property than rutile structure.…”