Tuning the sound frequency in the audible region during the synthesis of the precursor TiO2: Evaluation of the sound effect on the structure and photoactivity relationship.

Due to their low efficiency, photocatalytic processes do not meet the requirements of commercial applicability, requiring new approaches in adjusting structural and electronic properties. Studies have been conducted in the development of the sonocatalysis technique where materials with better activity and stronger structure are observed. Although TiO 2 can be easily prepared by traditional and relatively simple methods, it tends to crystallize in temperatures ranging from 673 K to 873 K. In general, this methodology promotes high shrinkage or collapse of the mesostructure and is eventually followed by an increase in nanoparticle size and a decrease in specific surface area. To obtain a non-agglomerated TiO 2 crystal sample with good photocatalytic properties, we studied the audible sound frequency during the synthesis of the TiO 2 precursor. All the TiO 2 samples were prepared using a coprecipitation method and sonocatalysis, with some samples of TiO 2 being impregnated with 10% nickel. The catalysts were prepared by keeping important variables constant during all synthesis and tuning the sound frequency on audible frequency. All the samples were synthetized in a "Synthesis Chamber" used for coprecipitation method preparations. The samples were characterized by TGA, XRD, SEM, EDX, and PTR. The photocatalysts were tested in photodegradation of the methylene blue dye under the UV-VIS light region. The influence of the chemical composition and the audible sound frequency application during the synthesis of the TiO 2 precursor was evaluated establishing a relationship between the structure and photoactivity. The results suggest that sound waves applied during sample preparation have provided a good degree of crystallinity to the material, which could influence the crystallite size and the photocatalytic activity of the samples. Therefore, the audible sound associated with the "Synthesis Chamber" should be used as a tool to prepare and adjust the structural and electronic properties of the photocatalysts to promote TiO 2 photoactivity. • Synthesis of TiO 2 particles through using Sonochemistry technique. • The catalysts were prepared keeping constant some important variables and tuning the sound on audible frequency. • The photocatalysts were tested in photo degradation of the methylene blue dye under UV-VIS light region. • The sound waves applied during sample preparation have provided a good degree of crystallinity to the material. [ABSTRACT FROM AUTHOR]