Preparation of Au-TiO2Hybrid Nano Particles in Silicate Film Made by Sol-Gel Method

Abstract

TiO2 nano particles with photo catalytic property were mixed with silica alkoxides solution with HAuCl4/4H2O. STS02 (purchased from Ishihara Sangyo Kaisha, Ltd.) was used as TiO2 nano particles. The average size of TiO2 nano particles was 7 nm in diameter. The gel film coated on glass substrate was heated and then HAuCl4/4H2O was thermally reduced at 390 degree. The coated silica gel film doped with HAuCl4/4H2O and TiO2 nano particles was turned into light blue from colorless gel film after heat treatment. The optical absorption spectrum showed the absorption peak of the film heated at 390 degree shifted to at about 650 nm compare to SiO2 film doped with Au nano particles without TiO2 nano particles that had absorption peak at 542 nm. On the other hand, the film formed from coating solution incorporated TiAA (titanium tetraisopropoxide chelated by acetyl acetone) as TiO2 source instead of TiO2 nano particles had absorption peak at 550 nm. That means there was no effect on formation of Au nano particles when TiAA was incorporated. The average size of the particles was found to be about 23 nm in diameter by TEM observation. Furthermore EDX (Energy Dispersive X-ray Fluorescence Spectrometer) analysis of nano particles in the film indicated that Au-TiO2 nano hybrid particles were formed. Simulation results also supported that the size in diameter of Au nano particles had little influence on the absorption coefficient of the silica film doped with Au nano particles.