A comparative study on the photocatalytic activities of microporous and nanoporous TiO₂ layers prepared by electrochemical anodization

In this paper, we present results of comparative studies on the photocatalytic activity of microporous and nanoporous titanium dioxide (TiO₂) layers formed on titanium substrates by electrochemical anodization at different voltages. Two sample groups each including four samples was prepared for microporous and nanoporous TiO₂ layer formation. Microporous TiO₂ layers were prepared in 1M H₂SO₄ solution in 10min. Nanoporous TiO₂ layers were formed in %1 HF solution in 30min and then annealed at 480°C in ambient air. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The photocatalytic activity of the samples was determined by assessing the decomposition rate of methylene blue (MB) solutions under UV light for different periods of time. By using the data obtained from the UV-Visible spectrophotometer, photocatalytic decomposition kinetics was also determined. The results indicated that nanoporous TiO₂ layers formed by applying 20V showed optimal photocatalytic performance, whereas the sample anodized at 250V exhibited the highest photocatalytic activity within its own sample group, nearly matching the photocatalytic activity of the highest performing sample.