Insights into Successful Hydrothermal Synthesis of Brookite TiO₂ Particles: From Micro to Nano

In this study, we investigate the hydrothermal synthesis of brookite phase TiO₂, resulting in the successful formation of flower-like microstructures and rod-like nanoparticles. In this method, a pH of 12.5 is critical for initiating the formation of the brookite phase prior to crystallization. Specifically, Na⁺ cations facilitate interactions between titanate layers, which promote this transition. Our findings indicate that a threshold concentration of Na⁺ ions is required to stabilize the brookite structure; deviations below this concentration instead favor the formation of anatase. Notably, we demonstrate that an optimal Na⁺ level enables the reliable formation of rod-like, ligand-free brookite nanoparticles. Photodegradation tests conducted with trichloroethylene as a representative pollutant showed promising photocatalytic efficiency for both structural forms, with the rod-like nanoparticles exhibiting superior activity.