Enhanced photocatalytic activity of (La, N) co-doped TiO₂ by TiCl₄ sol-gel autoigniting synthesis

(La, N) co-doped TiO₂ photocatalysts were synthesized using TiC₁₄ sol-gel autoignidng synthesis (SAS) starting from a complex compound system of TiCl₄-La(NO₃)₃-citric acid-NH₄NO₃-NH₃H₂O, in which the (La, N) co-doped process was accompushed in the formation of TiO₂ nanocrystals. The prepared samples were characterized by using X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalyfic activity of (La, N) co-doped titania by SAS was discussed in detail.