Effect of the length of TiO₂ nanotubes on the photoelectrochemical oxidation of phenylacetic acid anions

Nanocrystalline TiO₂ nanotube electrodes were fabricated by electrochemically anodizing the titanium in the electrolyte with an ethylene glycol with addition of 0.5% by weight NH₄F and amount of water (2% w/w). Structural properties of the obtained coatings have been investigated by scanning electron microscopy and Raman and XRD spectroscopy. When illuminated by a sunlight simulator, these electrodes demonstrate high activity in photoelectrochemical degradation of anions of phenylacetic acid from aqueous solutions of 0.1 M Na₂SO₄. Results of intensity-modulated photocurrent spectroscopy show that the photoelectrocatalysis efficiency is explained by suppression of the electron–hole pair recombination and increase in the rate of photo-induced charge transfer. Thus, nanotubes from TiO₂ can be considered as effective photoanodes.