Photoelectrochemical and Photocatalytic Oxidation Behavior of Organic Substances on TiO2 Nanotubular Films

Nanotubular films of titanium oxide have attracted interest recently due to their importance in basic scientific research and potential technology applications, e.g. photocatalyst, photovoltaic material, gas sensor, optical coating, biocompatible material for bone implants [1]. Several recent studies have indicated that titanium dioxide nanotubular films take advantages of both single crystalline and porous films and have improved properties compared to any other form of titania due to their superior electrical characteristics, high surface-to-volume ratio and size-dependent properties [2]. In the present work, highly dense, well-ordered TiO2 nanotube arrays (TNTAs) were prepared on Ti substrate by an electrochemical method. To investigate their potentials for environmental applications, the photocatalytic activity of TNTAs in methylene blue (MB) aqueous solution were evaluated; it was found that the photocatalytic activity of TNTA was strongly dependent on the crystallographic structure and morphology. The photoelectrocatalytic oxidation characteristics of methanol, a well-known radical scavenger and non-specific adsorbent to TiO2, were investigated by measuring open-circuit potential and potentiodynamic polarization curves. It was found that the photooxidation rates enhanced with increasing applied potential and methanol concentration