Influence of iron doping on photocatalytic activity of TiO₂ coatings formed on titanium by plasma electrolytic oxidation

This paper presents the results of our recent investigation focused on the preparation and possible photocatalytic application of iron doped TiO₂ coatings formed by plasma electrolytic oxidation of high purity titanium in electrolyte containing FeSO₄. The morphology, phase and elemental composition, and absorption band of the coatings were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The photocatalytic activity of coatings was evaluated by measuring the degradation of methyl orange under simulated sunlight conditions. It was found that the addition of iron precursor to electrolyte solution improves the photocatalytic properties of obtained coatings with respect to pure TiO₂ coating. The incorporation of iron in TiO₂ lattice was identified as the main factor affecting the increase of photocatalytic activity. The highest photocatalytic activity was observed when coatings were processed for 2 min with addition of 1 g/L FeSO₄ to electrolyte.