Effects of ultrasound/microwave irradiation on the sol-gel synthesis of titanium dioxide nanoparticles for photocatalyc application

Abstract

TiO2 nanoparticles were synthesized by the sol-gel method with the purpose of optimizing their morphological and structural properties, for their application in photocatalysis by varying the thermal treatment in the crystallization stage. Each sample was prepared according to the case with microwave irradiation (MO), ultrasound (US), combined mode (microwave-ultrasound (MC)) or conventional method (reflux), where the MC method has not been reported. It was found that the optical (edge energy (Eg)), textural and morphological properties depend on the type of irradiation during the crystallization stage. The SEM micrograms (scanning electron microscopy) showed two morphologies, one in the form of monoliths and the other as aggregates of lobular particles. In the case of MO and reflux, it is made up of aggregates of lobular particles, for US in the form of monoliths and finally for MC, the dominant morphology is due to the effect of US. For the evaluation in photocatalysis, it was observed in the samples studied that the higher the percentage of anatase phase, surface area, volume and pore size, all at the same Eg value, the greater the photodegradation of methyl orange. Therefore, TiO2 synthesized by the combined MC method was the best material obtained for photodegradation.