Fabrication and photocatalytic activity of porous TiO2 nanowire microspheres by surfactant-mediated spray drying process

A novel, porous TiO2 nanowire microsphere with a diameter of 3–8 μm was successfully fabricated via spray drying of TiO2 nanowire suspension with the assistance of surfactant (F127). The products were characterized by FESEM, XRD and N2 adsorption–desorption analysis and results revealed that the resulting TiO2 nanowire microspheres possessed a hierarchically macro/mesoporous structure, as well as a high BET surface area of 38.2 m2/g. Systematic studies showed that the presence of surfactant in the suspension feed for spray drying was critical in the formation of porous microspheres. The structure of the fabricated microspheres depends on the nanowire concentration in the feed. The TiO2 nanowire microspheres exhibited significant photocatalytic degradation of Methylene blue (MB) as compared to commercial TiO2 nanoparticles (P25). It was also revealed that the microspheres have excellent stability on photocatalytic activity and mechanical strength, which are both crucial factors when considering reuse of these photocatalysts.