Low temperature synthesis of anatase rare earth doped titania-silica photocatalyst and its photocatalytic activity under solar-light

Abstract

A series of rare earth (Sm 3+, Nd 3+, Ce 3+ and Pr 3+) doped titania-silica photocatalysts, as a reclaimed solar-light responsive photocatalyst, was prepared by sol–gel method with TEOS and TBT as precursors, by keeping the molar of TEOS:TBT constant at 1:1 and with different rare earth dopant content. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), UV–vis diffuse reflectance, Fourier transform infrared spectra (FTIR) and nitrogen adsorption/desorption isotherms. The characterizations found that only anatase phase is present in photocatalysts with high surface areas. The mean size is around 10.1 nm form TEM, which is consistent with the analytical result according to SEM. It can be seen that methyl groups exist in photocatalysts based on analysis of FTIR. The distinct band for Ti–O–Si vibration (∼970 cm −1) is observed as indicated from FTIR. Comparing to undoped TiO 2-SiO 2 photocatalyst, the rare earth doped TiO 2-SiO 2 photocatalysts exhibit obvious absorption in the 400–450 nm range with a red shift in the band gap transition. The experiments also confirmed that TiO 2-SiO 2 photocatalysts with rare earth ions dopant content increase the efficiency of interfacial adsorption and photocatalytic reactivity on the degradation of methylene blue (MB, 10 mg/L) in water under solar-light irradiation. Meanwhile, the rare earth doped TiO 2/SiO 2 photocatalysts remained floatable in the water surface after irradiation for 3 h. The solar-light driven photocatalysts with low preparation can be easily scaled up for industrial application, especially in the open water surface.