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

(La, N) co-doped TiO2 photocatalysts were synthesized using TiCl4 sol-gel autoigniting synthesis (SAS) starting from a complex compound system of TiCl4-La(NO3)3-citric acid-NH4NO3-NH3.H2O, in which the (La, N) co-doped process was accomplished 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 photocatalytic activity of (La, N) co-doped titania by SAS was discussed in detail.