The effect of high intensity ultrasound on the loading of Au nanoparticles into titanium dioxide

Novel metal/semiconductor nanocomposites have been synthesized from pre-formed components by applying high intensity ultrasound irradiation. Positively and negatively charged Au nanoparticles were intercalated into mesoporous TiO2 by sonication. The synthesized nanocomposites with implanted gold nanoparticles possess a narrow pore-size distribution around 7 nm and a large surface area of about 210 m(2)/g. The intercalation of the Au nanoparticles into the TiO2 framework depends on the charge of the Au nanoparticles, time and amplitude of ultrasonic treatment. The experiments show that at 20 min of ultrasonic irradiation the volume fraction of the negatively charged Au nanoparticles intercalated into TiO2 is 15%. By contrast, at the same time, 8.1% of positively charged Au nanoparticles with a diameter of about 6-7 nm enters into the TiO2 matrix. The characterization of the samples was carried out by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared measurements and BET analysis. The structure of TiO2 was not considerably affected by the intercalation of the Au nanoparticles. TiO2 doped with negatively charged Au nanoparticles presented a higher photocatalytic activity (75 wt.%) than TiO2 loaded with positively charged Au nanoparticles (62 wt.%), because of an enlarged surface area and quantity of Au nanoparticles in titania. (C) 2010 Elsevier B.V. All rights reserved.