PbS/CdS nanocrystal-sensitized titanate network films: enhanced photocatalytic activities and super-amphiphilicity

Titanate network films were grown in situ on a Ti foil by a fast microwave-assisted hydrothermal method. The titanate network (STN) films were formed by twisting of long one dimensional (1D) multi-walled titanate nanotubes. Compared with the traditional hydrothermal method, the applied microwaves can accelerate the reaction rate and this method can save time. To expand the light absorption capability, PbS and CdS nanocrystals were uniformly sensitized on the STN film. After sensitization, the light absorption was remarkably shifted to the long wavelength direction, while the network structures of the film were kept. The PbS-STN and CdS-STN films showed enhanced photocatalytic activities for MO degradation compared to the bare STN film and N-TiO(2) film. These enhanced photocatalytic activities were possibly due to the large BET surface areas of the titanate nanotubes, more light harvesting in the channels of the surface network structure, and the high separation probability of the photo-generated electron-hole pairs. Furthermore, it is interesting that all of the STN, PbS-STN, and CdS-STN films showed the super-amphiphilicity without any light irradiation, which may be due to the roughness of the surface network structures. And this super-amphiphilicity was kept even after exposure to air for more than 6 months.