Enhancing the photocatalytic oxidation of dibenzothiophene using visible light responsive Fe and N co-doped TiO2 nanoparticles

Fe and N co-doped TiO2 nanoparticles were synthesized by an ultrasonic assisted impregnation reaction method. The prepared samples were characterized using XRD, BET, FE-SEM, XPS, FT-IR, and UV-vis DRS techniques. Fe and N co-doping resulted in a decrease in the crystallite size and an increase in the specific surface area. Photocatalytic oxidation of dibenzothiophene (DBT) in diesel model fuel was investigated using Fe and N co-doped TiO2 nanocatalyst under visible light irradiation and air bubbling. The photocatalytic activity of the Fe and N co-doped TiO2 nanoparticles was found to be considerably higher than that of the mono-doped counterparts. The differences in the photocatalytic activity of the prepared samples were discussed. It can be inferred that the visible light absorption alone is not a sufficient criterion for the photocatalyst activity. The efficient photocatalytic activity of the Fe and N co-doped TiO2 can be attributed to the co-operation of the Fe and N dopants. The presence of nitrogen and iron resulted in extending the absorption to the visible region. Under aerated conditions, Fe ions can considerably promote the photogenerated charge separation and consequently decrease the recombination rate of electron-hole pairs. The optimum iron content for Fe and N co-doped TiO2 was determined as 0.5 wt%. Photocatalyst loading of 3 g L-1 and air flow rate of 200 mL/min were identified as optimum reaction conditions for photocatalytic desulfurization of the model fuel.