Research On Synthesis And Photocatalytic Activity Of Co-Doped TiO₂ Nanotubes

In this article, both pure and Fe, Co, Ni doped TiO2 nanopowders were fabricated by sol-gel method using tetrabutyl titanate (TBT) as precursors. These powders were used to prepare nanotubes by hydrothermic process. The properties of products were characterized by SEM, TEM, XRD and EDS. The performance of TiO2 nanotubes promoting photodegradation of rhodamine B was studied.The results show that the diameter of nanotubes was about 35 nm with a length ranging from 200 nm to 1000 nm. The higher the heat treatment temperature of raw nanopowder, the better was the dispersed state of TiO2 nanotubes.Compared with nanopowder precursors, the crystal structure of TiO2 nanotubes keeps unchanged. The temperature of crystal structure transition may increase by doping Fe and Co, but decrease by doping Ni.The photocatalytic properties of nanotubes are better than that of nanopowder precursors. There is the most appropriate doping ratio of Co for Co-doped TiO2 nanotubes. The photocatalytic ability of Co-doped TiO2 nanotubes for degradation of rhodamine B will deteriorate when the doping level is both higher and lower than the best value. The photocatalysis performance of nanotubes will descend with the increasing original concentration of rhodamine B. There was a most suitable adding amount of nanotubes in the system.The photocatalytic reaction of Co-doped TiO2 nanotubes for degradation of rhodamine B is first order reaction. Rate constant only depends on doping ratio of Co for Co-doped TiO2 nanotubes and has nothing to do with both original concentration of rhodamine B and adding amount of nanotubes in the system.The photocatalytic reaction of both Fe-doped and Ni-doped TiO2 nanotubes for degradation of rhodamine B are also first order reaction.Compared with pure TiO2 nanotubes, the photocatalytic behavior of the Fe-series doped nanotubes is much more better under the same condition, which is of the following order: Co2+>Fe3+>Ni2+>pure.