Photocatalytic characteristics of TiO2 nanotubes with different microstructures prepared under different pulse anodizations

In this work, different positive voltages of a pulsed waveform, time intervals and electrolyte stirring were used to prepare by anodization of pure titanium plates, a series of TiO2 thin films based on nanotubes with different morphologies and dimensions. Electrolyte stirring results in large size TiO2 nanotubes with uneven surface morphology and less oriented directions. The titanium plates containing the TiO2 thin films were further annealed at 450 °C for 30 min under air. It was found that only crystalline anatase was formed under this condition. Both methylene blue degradation and antibacterial tests against Escherichia coli were performed to evaluate the photocatalytic performance of these TiO2 films. Better methylene blue degradation ability was achieved by TiO2 nanotubes prepared under electrolyte stirring. However, the antibacterial ability of the annealed TiO2 nanotubes was affected by their inner diameter rather than their length. It is also concluded that the anodized TiO2 nanotube arrays fabricated in this work are promising for photo-induced methylene blue degradation and bacteria killing applications.