Synthesis and formation mechanism of hematite hollow microspheres by a one-pot templateless surfactant-free hydrothermal process

摘要

Hollow microspheres of hematite (α-Fe_2O_3) were prepared by a simple hydrothermal treatment of ferrous ammonium sulphate hexahydrate ((NH_4)_2Fe(SO_4)_2 ·6H_2O) aqueous solution without any surfactants and additives at 180-200 ℃. The products were characterized by XRD, FE-SEM and TEM. The results show that α-Fe_2O_3 hollow microspheres are about 1 μm in diameters and are composed of α-Fe_2O_3 nanopar-ticles with a diameter range from 50 nm to 150 nm. The effects of reaction parameters such as reaction time, temperature and [(NH_4)_2Fe(SO_4)_2·6H_2O] on the morphology of the final product were investigated. A potential formation mechanism of α-Fe_2O_3 hollow microspheres was also proposed, where the intermediate, urchin-like goethite, served as a sacrificial template for the formation of hollow structure. The reaction parameters-depended morphologies of the final products consisted well with the proposed formation mechanism.