Synthesis of TiO2 microspheres by ultrasonic spray pyrolysis and photocatalytic activity evaluation

This work presents and discusses TiO2 microspheres synthesized by ultrasonic spray pyrolysis. A simple setup allowed for the continuous production of TiO2 nanocrystals. During the process, the particles experienced a short residence time (ca. 40 s) at the set temperature (700 °C), promoting phase stability and limited particle coarsening. As a result, porous anatase TiO2 microspheres with crystallite size ∼8 nm and specific surface area ∼27 m2 g-1 were produced as soft spherical agglomerates of ∼0.6 μm. Samples were analyzed using X-ray diffraction, BET specific surface area, SEM, TEM, XPS, and UV/Vis diffuse reflectance spectra, as well as in their photocatalytic activities. Photoactivity was evaluated through the degradation of the model contaminant acetaminophen under UV irradiation, and the results confirmed the superior performance of the synthesized TiO2 microspheres, exceeding the commercial standard TiO2 P25 by ca. 60% in terms of reactivity.