Fabrication of TiO_2/CdS Coaxial Heterojunction and Its Photocatalytic Properties

TiO2 nanotube arrays on titanium sheet were prepared by anodized oxidation method and filled with CdS in the interior of the annealed TiO2 nanotubes by direction current(DC) electrodeposition.The TiO2/CdS heterojunctions were characterized through scanning electron microscopy(SEM),energy dispersive spectrometer(EDS) and X-Ray diffraction(XRD).The results show that TiO2/CdS coaxial nanocables are orderly arrayed,their diameters are uniform and the chemical ratio of Cd and S is closed to 1:1.The TiO2 annealed at 450℃ in air is anatase and the deposited CdS is hexagonal phase.UV-visible absorption spectroscopy and methyl orange dye by photocatalytic degradation under UV light of the pure TiO2 nanotubes and TiO2/CdS heterojunction are investigated.Compared with the pure TiO2,TiO2/CdS heterojunction has an obvious red-shift on the edge of TiO2 absorption and their photocatalytic activity is obviously improved,with maximum degradation rate of methyl orange as 99.4%.