TiO2/Bi2O3 coatings formed by plasma electrolytic oxidation of titanium for photocatalytic applications

TiO2 coatings modified by Bi2O3 particles were successfully formed by plasma electrolytic oxidation (PEO) process of titanium in supporting electrolyte (10 g/L Na3PO4·10H2O) with the addition of Bi2O3 particles. The morphology, crystal structure, chemical composition, and optical properties of formed PEO coatings were investigated by scanning electron microscopy, energy-dispersive spectroscopy, X-ray fluorescence, X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, and photoluminescent techniques. The photodegradation of methyl orange under simulated sunlight condition was used to determine the potential of TiO2/Bi2O3 coatings in photocatalysis. The photocatalytic activity (PA) of TiO2/Bi2O3 coatings is higher than that of pure TiO2. PA of TiO2/Bi2O3 coatings is highly dependent on the amount of Bi2O3 particles in the supporting electrolyte and the highest PA was observed for TiO2/Bi2O3 coating formed in supporting electrolyte with the addition of 1.2 g/L of Bi2O3 particles. Enhanced PA is related to the reduction of photo-generated electron/hole recombination rate as a result of TiO2 and Bi2O3 coupling.