Spray pyrolysis synthesis and UV-driven photocatalytic activity of mesoporous AlO@TiO microspheres.

Mesoporous microspheres of AlO@TiO were effe ctively and rapidly prepared by the sol-spray pyrolysis (SP) method. Ultrasonic-induced droplets containing titania sol, boehmite sol, and citric acid (CA) were pyrolyzed to γ-AlO-incorporated anatase TiO microspheres. The SP-derived AlO@TiO microspheres exhibited higher porosity and lower bandgap energy than pure TiO and commercial P25. The TiO microspheres incorporated with 5 wt% amorphous γ-AlO efficiently removed tetracycline (TC) after 60 min of pre-adsorption and 140 minutes of UV illumination (removal efficiency ~ 91%, surpassing those of pure TiO and commercial P25). Introducing amorphous γ-AlO into the anatase TiO matrix created a synergetic effect that enhanced the accumulation of TC onto the catalyst surface; meanwhile, the formation of defective heterojunctions favored the separation and immigration of the photo-generated holes and electrons. In a reaction mechanism analysis, h and O radicals were identified as the main instigators of TC photooxidation. Furthermore, the SP-derived AlO@TiO microspheres demonstrated good stability and renewability in durability tests. The study provides a simple and scalable method for manufacturing AlO-decorated TiO microspheres with improved adsorption and photocatalytic performance.