Template-free synthesis of monodisperse α-Fe2O3 porous ellipsoids and their application to gas sensors

Monodisperse porous alpha-Fe2O3 ellipsoids composed of primary nanocrystals were synthesized by a facile one-step template-free hydrothermal method. Field emission scanning electron microscopic and transmission electron microscopic results revealed that these porous ellipsoids were built from a large number of nanoparticles with sizes of about 10-20 nm. The morphology and size of the as-prepared products could be tailored by simply adjusting the amounts of hexamethylenetetramine and reaction temperature. A possible formation mechanism was proposed on the basis of the results of time-dependent experiments. When used as sensing materials in chemical sensors, the as-prepared porous alpha-Fe2O3 ellipsoids exhibit a high response to ethanol.