Photoconductivity studies of gold nanoparticles supported on amorphous and crystalline TiO2 matrix prepared by sol-gel method

Gold metallic nanoparticles embedded in amorphous and crystalline TiO2 matrix as powders and films were synthesized by the sol gel process at room temperature. The TiO2 matrix was synthesized by using tetrabutyl orthotitanate as the inorganic precursor. The films were spin-coated on glass wafers. The samples were annealed at at 100 degrees C for 30 minutes and sintered at 520 degrees C for 1 hour to generated anatase and rutile phases. The film shows a light blue colour. The amorphous film exhibits an absorption band at 568 nm. The crystalline film exhibit two absorption peaks located at around 402 (from TiO2 matrix) and 651 nm is due to the surface plasmon resonance of the gold nanoparticles. The films were studied using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, high resolution transmission electronic microscopy and UV-Vis absorption spectroscopy. Photoconductivity studies were performed on amorphous and crystalline TiO2/Au films. The experimental data were fitted with straight lines at darkness and under illumination at 515 nm and 645 nm. This indicates an ohmic behavior. Transport parameters were calculated.