Synthesis, characterization and photocatalytic activity of neodymium, nitrogen and neodymium–nitrogen doped TiO2

Highlights: ► The influence of Nd/N-doping on the sol–gel prepared TiO2 characteristics is described. ► The photocatalytic activity of the materials for dye degradation is established. ► The activity depends on the catalysts composition and synthetic conditions. ► The doping has a positive under UV and no or negative effect at solar irradiation. ► Degussa P25 TiO2 reveals high activity at sunlight illumination. -- Abstract: TiO2 doped with 0.1–10% Nd3+ or 1.8% nitrogen or co-doped with both dopants as well as Nd2Ti2O7 are synthesized by a sol–gel. The phase composition, crystal structure, morphology, optical properties and binding energies of the doped titania were investigated. The photocatalytic activity was tested for malachite green dye degradation and compared with the results obtained by dopant-free TiO2 synthesized using the same procedure and with the commercial Degussa P25 product. The influence of the dopant type and relative content, temperature of ignition in the course of the synthesis, pH of the reaction medium and the type of the illumination light on the efficiency of the prepared catalysts were determined. A positive effect of Nd- and N-doping on the apparent degradation rate constant under UV irradiation and negative one of Nd-presence at solar illumination is found. Nd–N-codoping has a negative effect on the photocatalytic activity.