Abstract
TiO2 is widely used in the field of environment and energy, such as dye-sensitized solar cells and photocatalysts for the degradation of organic pollutants. This study is to enhance of the photodegradation of dye (Sulforhodamine B as a model compound) under visible light by TiO2 pretreated with alkaline hydrogen peroxide. Modified TiO2 nanoparticles were characterized by dynamic laser light scattering (DLS), fourier transform infrared (FT-IR), thermogravimetry analysis (TGA), surface area analysis (BET), high-resolution transmission electron microscopy (HRTEM) and X-ray powder diffraction (XRPD). In addition, electron paramagnetic resonance spectrometer (EPR) was utilized to observe the formation of hydroxyl radicals in the system. TiO2 could not only increase the density of surface hydroxyl groups on the TiO2 surface (13.89 OH/nm2), but also lead to smaller particle size (4 nm). The dispersion and photocatalytic activity of the modified TiO2 were greatly enhanced. On the other hand, TiO2 pretreated with UVC light could increase the surface hydroxyl groups on the TiO2 surface though, the degradation rate was not unexpectedly enhanced. The effect of metal ion (Fe3+, Cu2+, Zn2+ and Al3+) on the photocatalytic activity of the modified TiO2 was investigated under visible light. The results show that Fe3+ accelerated the photodegradation of dyes in aqueous modified TiO2 dispersions with one order of magnitude larger than commercial P-25. This may be ascribed to the complexation of the hydroxyl groups bound to TiO2 surface with Fe3+ to form Fe(OH)2+.