Controlled synthesis of porous FeCO3 microspheres and the conversion to α-Fe2O3 with unconventional morphology

Porous FeCO3 microspheres were synthesized via a facile surfactant- and template-free hydrothermal process. The diameters of FeCO3 microspheres are about 20±5 μm. Each FeCO3 microsphere was self-assembled with a number of trilobed wheel-like subunits. The influence of preparation conditions, such as temperature, reaction time and content of urea on the phase composition and morphology were investigated. Based on time-dependent experiments, we proposed the possible formation mechanism for the self-assembled FeCO3 micro-spheres. After calcination at 650 °C, α-Fe2O3 derived from FeCO3 retained the original size and morphology of FeCO3. The prepared α-Fe2O3 with the novel microstructure shows wide potential application as photocatalysts.