Preparation of Au/TiO2 nanocomposite particles with high visible-light photocatalytic activity in inverse miniemulsions

Au/amorphous TiO2 nanocomposite particles with high visible-light photocatalytic activity were conveniently prepared in inverse miniemulsions. The materials were synthesized through a combination of a sol–gel process and in situ reduction of HAuCl4 by hydrazine to Au nanoparticles in the nanocomposite particles. The photocatalytic activity of the as-synthesized Au/amorphous TiO2 nanocomposite particles is much higher than that of the Au/anatase TiO2 and Au/rutile TiO2 nanocomposite particles prepared by calcination. Therefore, no further heat treatments are required to achieve visible-light photocatalytic active catalysts. The loading of Au in the nanocomposite particles could be conveniently tuned by varying the HAuCl4 loading in the dispersed phase of the inverse miniemulsions. Only a small amount of Au was required to achieve a high photocatalytic activity. The size, particle morphology, TiO2 phase, optical property, elemental content and distribution, and pore properties of the Au/TiO2 nanocomposite particles were systematically characterized by dynamic light scattering, transmission/scanning electron microscopy, X-ray diffraction, Raman spectroscopy, UV–vis spectroscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and N2 sorption measurements.