Preparation and photocatalytic properties of N-doped nano-TiO2/muscovite composites

Using muscovite as the carrier, TiCl4 as the source of titanium, urea as the neutralizer, nano-TiO2/muscovite composites (TiO2/M) were prepared by the method of hydrolysis-precipitation. Then N-doped TiO2/M composites were prepared by using urea as dopant after calcination at 500 °C for 2 h. The samples were characterized by XRD, SEM, EDS, XPS and DUV methods. The photocatalytic activity of samples was evaluated by degradation of methyl orange under visible light irradiation (halogen lamp, 250 W). The results showed that the surfaces of muscovite were uniformly coated by nano-TiO2, which combined with the muscovite surface via the SiOTi and OTiN bonds. The grain growth of TiO2 and the phase transformation from anatase to rutile were restrained by the doping of nitrogen. Meanwhile, the absorption edge of samples after doping exhibited red-shift from 390 nm to 430 nm, showing obvious response to visible light. The degradation rate of methyl orange (20 mg L−1) reached 67.15% after irradiation of 250 W halogen lamp for 1 h (doping ratio was 1:3), while the degradation rate of un-doped sample was just 8%.

► By hydrolysis-precipitation, nano-TiO2 particles successfully sedimentate on muscovite surfaces, and TiO2 coating is very dense and uniform. ► By the doping of nitrogen, N-doped nano-TiO2/muscovite composites show obvious response to visible light and photocatalytic activity. ► Compared with pure TiO2 powders, N-doped nano-TiO2/muscovite composites present better recycle property through the repeated experiments.