One-pot synthesis of bundle-like β-FeOOH nanorods and their transformation to porous α-Fe₂O₃ microspheres

Bundle-like β-FeOOH nanostructures were successfully synthesized by a simple hydrolysis process in the presence of urea. The as-prepared products were characterized by X-ray power diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results indicated that bundle-like nanostructures were composed of well-aligned single crystalline nanorods with the diameters of 20-25 nm and the lengths of 100-150 nm. The corresponding porous α-Fe₂O₃ microspheres can be easily obtained by calcining the bundle-like β-FeOOH precursor. The achieved porous hematite microspheres, which are several hundreds of nanometers in diameter, exhibited high response for detecting ethanol, because the unique porous architecture effectively shortened the gas diffusion distance and provided highly accessible open channels and active surfaces for the target gas.