Research On Doping Of Nano-TiO₂ And Photocatalysts Of Bi(Nb)OCl

This paper aimed at enhancing the photoactivity of nano-TiO₂, disclosing the nature of effects of doping on nano-TiO₂. According to the current problems such as low quantum efficiency, limited available wavelength rang, resulted from the practical using of photocatalysis, nano-particles of TiO₂ doped with various transition metal ions and rare earth metal ions were prepared through wet impregnation method. Doped and pure TiO₂ samples were characterized by X-ray diffraction (XRD), BET surface area meter (BET), UV–Vis diffuse reflection spectra (UV-Vis). The influence of ion doping to the photoactivity of nano-TiO₂ was evaluated by the photodecomposition of rhodamine B. At the same time, TiO₂/UV photo-degradation of dye rhodamine B was investigated in aqueous heterogeneous suspensions, and the activity of photocatalytic degradation was evaluated through UV-Vis spectrophotometer. Kinetic equation of photocatalytic degradation of dye rhodamine B was also discussed. Additionally,Bi based photocatalysts BiOCl and Bi4NbO8Cl also researched on visible-light driven degradation activity and reaction mechanism.In the part of ion doping, the influences of doping ion species and added amount of doping ions, calcination temperature to the crystal structure and photoactivity were all studied. The results showed that photocatalytic activities of TiO₂ doped by Fe3+,Cu2+,Ni2+ among transition metal ions were lower than pure TiO₂, photocatalytic activity of TiO₂ doped by Zn2+ is higher than pure TiO₂.The sample doped by Zn2+ with 1.5% concentration at 500℃calcination temperature for 5 hours has highest photocatalytic activity. The sample doped by La3+ with 0.6% concentration at 500℃calcination temperature for 5 hours has highest photocatalytic activity.The photo-degradation of dye rhodamine B was investigated, and the influences of initiative concentration of rhodamine B, the added amount of TiO₂ and acidity of solution to the photoactivity were discussed. Kinetic eqution was acquired by Langmuir Hinshelwood (L-H) former.Bi based photocatalysts BiOCl and Bi4NbO8Cl with layer structure both degrade rhodamine B under visible-light irradiation. But they have different reaction mechanisms, with dye photosensitive mechanism and photocatalytic mechanism, respectively. It is concluded that Bi(Nb)OCl materials are promising visible-light driven photocatalytic materials.