Organized Arrays of TiO2/ZnO Nanotube Coaxial Core-Shell Heterojunctions for Photocatalytic Applications

Organized arrays of TiO2/ZnO nanotube coaxial core shell heterojunctions were synthesized by using the anodic aluminum oxide (AAO) template and sol gel method. The process is simple, convenient, and is suitable to produce large size and well ordered core shell heterojunction arrays. The resulting nanocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area. The results showed that the TiO2/ZnO composite nanotubes were successfully grown into the channels of the AAO template by the sol gel method. In comparison with the pure nanotube (TiO2 or ZnO) array, the coaxial heterogeneous structure (TiO2/ZnO) showed higher photocatalytic activity for degradation of methyl orange under UV light irradiation. More importantly, the new synthesis technique could be extended to prepare other binary narrow band-gap compound semiconductors for toxic pollutant photocatalytic degradation.