The dispersion of Au nanoparticles in SiO2/TiO2 layered films by the liquid phase deposition (LPD) method

Au nanoparticles dispersed SiO2/TiO2 layered films were prepared by a novel wet process known as the liquid phase deposition method. Their structure, surface morphology, chemical states, particle size and optical properties were investigated by using X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, scanning electron microscopy and ultraviolet-visible absorption spectroscopy. Au nanoparticles were obtained in the both oxide matrices by the thermal reduction. The XPS studies showed that AuIII and AuI ionic species were co-deposited in the SiO2/TiO2 layered films. TEM observation revealed that the most of Au nanoparticles were transferred into the crystalline anatase TiO2 matrix after the heat treatment. It was found that, the distributed Au nanoparticles were more stable in the crystalline TiO2 than amorphous SiO2 matrix. The mean size of Au in SiO2 (∼ 15 nm) is larger than that of TiO2 (∼ 5 nm) matrix. An absorption peak of Au particles was observed at the wavelength of ca. 570 nm which could be assigned to the surface plasmon absorption band of Au nanoparticles.