Preparation of lanthanum and carbon co-doped TiO₂ and photocatalysis under visible irradiation

TiO₂-based photocatalysis technology was developed and applied to photodegradation of organic contaminants by utilizing solar energy effectively. Pure and doped or co-doped TiO₂ catalysts with various amounts of lanthanum and carbon were obtained by a modified sol-gel process, in which tetrabutyl titanate was used as precursor and lanthanum nitrate, tetrabutylammonium hydroxide as ion donors. The as-prepared photocatalysts were found to be of anatase phase, higher specific area, and visible response by means of XRD, BET and UV-vis spectra analysis. The co-doped TiO₂ catalysts showed higher photocatalytic activity in degradation of rhodamine B, methyl orange and 4-chlorphenol under Xe lamp, sunlight or daylight irradiation than that of pure and single doped ones. Photodegradation experiments showed that the co-doped catalyst with 0.5% (molar ratio) lanthanum calcinated at 500 °C was of the highest catalytic efficiency under visible irradiation. The higher visible light photocatalytic activity of codoped TiO₂ was attributed to the doped carbon that lowered the band gap and the doped lanthanum which maintained the charge balance at the same time.