The pH Influence on the Preparation of Hollow Fe_2O_3 Spheres by Hydrothermal Method

摘要

In this paper Fe_2O_3 precursor coating on the surface of carbon balls was prepared by hydrothermal method using Fe(NO_3)_3·9H_2O and glucose as the raw materials. After calcination Fe_2O_3 hollow sphere could be achieved. The influence of pH value on the preparation of hollow Fe_2O_3 spheres was studied using XRD and SEM respectively. The results show that the pH value has no effect on the formation of Fe_2O_3 phase, but has a giant influence on the morphology of the hollow spheres. The Fe_2O_3 hollow spheres were achieved when the pH value was between 3 and 7. The particles with sheet and block structure form when pH<3 or pH>7. The mechanism was studied, When 3H<7.8, the absorption action of Fe(OH)_3 on the carbon balls is changed from the electrostatic interaction to the chemical interaction due to positive ζ potential, which benefits producing homogeneous hollow spheres.