Effect of Applied Potential on the Formation of Self-OrganizedTiO2Nanotube Arrays and Its Photoelectrochemical Response

Abstract

Self-organized TiO2nanotube arrays have been fabricated by anodization of Ti foil in an electrochemical bath consisting of 1 M of glycerol with 0.5 wt% of NH4F. The effects of applied potential on the resulting nanotubes were illustrated. Among all of the applied potentials, 30 V resulted in the highest uniformity and aspect ratio TiO2nanotube arrays with the tube's length approximately 1 μm and pore's size of 85 nm. TiO2nanotube arrays were amorphous in as-anodized condition. The anatase phase was observed after annealing at 400∘Cin air atmosphere. The effect of crystallization and effective surface area of TiO2nanotube arrays in connection with the photoelectrochemical response was reported. Photoelectrochemical response under illumination was enhanced by using the annealed TiO2nanotube arrays which have larger effective surface area to promote more photoinduced electrons.