Self-doping of Ti3+ in TiO2 through incomplete hydrolysis of titanium (IV) isopropoxide: An efficient visible light sonophotocatalyst for organic pollutants degradation

Herein, introduction of Ti3+ in TiO2 through incomplete hydrolysis of titanium tetra isopropoxide (TTIP) was demonstrated successfully for the first time. Interestingly, instantaneous addition of water to TTIP led to the formation of oxygen vacancies due to the incomplete hydrolysis and subsequent thermal activation induced the formation of Ti3+ site in the TiO2 as confirmed by EPR and XPS studies. Importantly, the slow addition of water to TTIP did not induce the formation of Ti3+ sites and indirectly ascertained the complete hydrolysis of TTIP. The catalytic efficiency of Ti3+-self-doped TiO2 was evaluated by sonophotocatalytic degradation of methyl orange (MO) dye and tetracycline (TC) antibiotics under visible light illumination. In comparison with individual effects of light and ultrasound, similar to 4 and similar to 1.2 folds synergistic effect was achieved for MO and TC degradation when ultrasound was combined with visible light due to synergistic production of (OH)-O-center dot radical by ultrasound and visible light.