Synthesis and characterization of kaolinite/TiO2 nano-photocatalysts

Kaolinite/TiO2 nano-photocatalysts were prepared by TiCl4 hydrolysis method. The materials were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL), ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS) and scanning electron microscopy (SEM). The photocatalytic activity was evaluated by the degradation of methyl orange in aqueous solution. The results show that kaolinite facilitates the formation of anatase, restrains the transformation of anatase to rutile and causes the absorption edge of TiO2 shift to higher energy region. TiOSi bonds form on the interface of kaolinite and TiO2. TiO2/kaolinite calcined at 200 °C shows a high photocatalytic activity due to the smaller crystallite size, the abundant surface oxygen vacancies and defects, and the lower recombination rate of electron–hole pairs of anatase TiO2.