An amorphous TiO2 sol sensitized with H2O2 with the enhancement of photocatalytic activity

An amorphous free-impurity TiO2 sol was synthesized only by means of ultrasonic dispersing of Ti(OH)4 precipitation without any peptizing agents. Anatase sol was obtained by hydrothermally treating the amorphous TiO2 sol. Photocatalytic tests showed that the amorphous sol exhibited higher photocatalytic activity for the photodegradation of methylene blue (MB) under visible light and UV irradiation than anatase sol and P25 TiO2. The photocatalysts were characterized by UV–visible spectroscopy, Raman spectrometer, photoluminescence (PL), FTIR, TEM, XRD, and XPS. The results showed the peroxide titanium complexes were formed on TiO2 sol particles sensitized with H2O2. More peroxide complexes and stronger vis absorption were observed for the amorphous TiO2 sol sensitized with H2O2.The sensitization of H2O2 would completely quench PL of the amorphous sol, but little impact on the anatase sol. The surface structure with fewer physisorbed water molecules facilitated the sensitization of H2O2 to the amorphous TiO2 sol particles, which resulted in the generation of more OH radicals and higher photocatalytic activity under both visible light and UV irradiation.