Preparation of short, robust and highly ordered TiO2 nanotube arrays and their applications as electrode

The short, robust and highly ordered TiO2 nanotube arrays (TNAs) electrode was prepared by sonoelectrochemical anodization of titanium in HF-H2O electrolyte solution (referred as short TNAs, STNAs). The self-organized arrays of titania nanotubes of approximately 12-65 nm in diameter and 75-280 nm in length can be synthesized at anodic voltage of 5-20 V. The electron transport process within the STNAs electrode was much favorable in comparison with that for the long TNAs electrode synthesized by conventional magnetic agitation technique (referred as long TNAs, LTNAs), as confirmed by the obviously enhanced photocurrent response of STNAs electrode either in 0.02 M Na2SO4 electrolyte solution or in different concentrations of glucose solution or under different intensities of UV illumination. To investigate their photoelectrochemical applications, degradation of tetracycline, a typical pharmaceutical and personal care products (PPCPs), was carried Out using photoelectrocatalytic (PEC) means, comparing with electrochemical (EC) and photocatalytic (PC) processes. The kinetic constant of the PEC process of STNAs electrode was similar to 3.17 times as high as its PC process. The color removal rate of tetracycline by STNAs electrode achieved 81% within 3 h, which was 21% higher than that for LTNAs electrode. In degrading tetracycline, 41% of TOC was mineralized using the STNAs electrode against 23% using LTNAs electrode under similar conditions. Such kind of titania nanotubes will have many potential applications in various areas as an outstanding photoelectrochemical material. (C) 2009 Elsevier B.V. All rights reserved.