Sonodegradation and photodegradation of methyl orange by InVO4/TiO2 nanojunction composites under ultrasonic and visible light irradiation

Abstract

The InVO4/TiO2 nanojunction composites with different weight ratio of 1:10, 1:25, 1:50 and 1:100 were successfully constructed using an ion impregnate method, followed by calcining temperature 400°C for 2h in Ar. The sono- and photo-catalytic activities of the InVO4/TiO2 nanojunction composites were evaluated through the degradation of methyl orange (MO) in aqueous solution under ultrasonic and visible light irradiation, respectively. The experimental results determined that the (1:50) InVO4/TiO2 nanojunction composite has exhibited the highest sonocatalytic activity. It can be ascribed to vectorial charge transfer at the co-excited InVO4/TiO2 interface under ultrasonic irradiation, results in the complete separation of electrons and holes. Interestingly, the (1:25) InVO4/TiO2 nanojunction composite displayed superior photocatalytic activity for MO degradation under visible light, indicating that InVO4 as a narrow band gap sensitizer can expand photocatalytic activity of TiO2 to visible region, and the charge transfer can be formed from high energy level of InVO4 conduction band to the low energy level of TiO2 conduction band in a present of excited InVO4 alone under visible light irradiation. The sono- and photo-catalytic activities of the InVO4/TiO2 nanojunction composites were found to be dependent significantly on different InVO4 contents, which can be explained by the influence of charge transfer on the basis of the work functions of different catalysis mechanism.