Hollow Al2O3 nanospheres with well-defined structure and shape were successfully prepared via flame spray pyrolysis (FSP) in the presence of a surfactant as droplet stabilizer. The morphology and structure of the nanospheres were systematically characterized by transmission electron microscopy, scanning electron microscopy, and N 2 sorption. A solution of hydrated aluminum nitrate, polyethylene glycol (PEG) and absolute ethanol was sprayed into a flame to transform droplets into particles after evaporation and surface nucleation, forming hollow Al2O3 nanospheres from aluminum nitrate decomposition. The surfactant was found effective in producing smaller droplets because of decreased surface tension and viscosity, while the combination of oxygen atoms on PEG chains and aluminum ions in solution reduced interfacial turbulence, leading to increased stability of the droplets.
