A facile urea-hydrolysis calcination process for the preparation of α-Fe2O3 nanoparticles and α-Fe2O3 nanorods and their fabrication mechanisms

A facile urea-hydrolysis calcination process for the preparation of α-Fe2O3 nanoparticles and α-Fe2O3 nanorods was introduced. The effects of hydrolysis temperature, Fe3+ concentration, and the molar ratio of urea and Fe3+ on nanorod-like precursors and α-Fe2O3 nanomaterials were investigated. The average length and diameter of the nanorod precursors increased with the increasing hydrolysis temperature, Fe3+ concentration, and molar ratio of urea and Fe3+. When the molar ratio of urea and Fe3+ was not less than 5, the α-Fe2O3 nanoparticles were produced. However, when the molar ratio was not greater than 4, the α-Fe2O3 nanorods could be obtained. In addition, the average diameter of the α-Fe2O3 nanoparticles was the largest when the hydrolysis temperature was 85 °C. With the increase in Fe3+ concentration, the average diameter of the α-Fe2O3 nanoparticles was enlarged. The average length and diameter of the α-Fe2O3 nanorods increased with the increase in hydrolysis temperature and Fe3+ concentration. All the results suggested that the rod-like structure of the precursors provided a possibility and the template for the fabrication of α-Fe2O3 nanorods, and the content of Fe3+ in the rod-like precursors played the decisive role in the morphology of the α-Fe2O3 nanomaterials.