Hierarchical rutile/anatase TiO2 nanorod/nanoflower thin film: Synthesis and characterizations

Hierarchical TiO2 nanorod/nanoflower thin film was synthesized on fluorine doped fin oxide glass via hydrothermal and aqueous chemistry methods. According to field emission scanning electron microscopy results, the thin film was crack-free and uniform. Primary nanorods had an average diameter of 95 nm and a length of 2 mu m. They were perpendicular to the substrate owing to the TiO2 prenucleation. Growth of the nanoflowers on the nanorods could increase both the specific surface area and roughness. X-ray diffraction and Raman spectroscopy showed that the nanorods were rutile; while the nanoflowers were anatase. Efficient electron transfer from anatase to rutile could therefore occur. According to the diffuse transmittance spectroscopy examination, the light harvesting rate was ameliorated and the band gap energy reduced to 2.83 eV. This was attributed to the F doping the sample during synthesis. The enhancement of the photoelectrochemical activity allowed substitution of the TiO2 nanorod/nanoflower thin film for the traditional TiO2 nanorods usually used in solar cells, sensors, and photocatalytic systems.