Porous α-Fe2O3 hollow microspheres: Hydrothermal synthesis and their application in ethanol sensors

• Porous α-Fe2O3 hollow microspheres were prepared by a hydrothermal method without templates.
• Special microstructures lead to the good gas-sensing properties.
• The porous α-Fe2O3 hollow microspheres exhibit a high response to ethanol vapor.

The hydrothermal method was employed to synthesize α-FeOOH hollow microspheres by using Fe(NO3)3·9H2O, oxalic acid and urea without templates. The porous α-Fe2O3 hollow microspheres were obtained by calcining the α-FeOOH precursors at 300 °C for 2 h. The structure and morphology of the as-synthesized products were characterized by techniques of powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N2-sorption analysis. XRD studies indicated that the as-prepared product was well-crystallized hematite phase of α-Fe2O3. The SEM and TEM images showed that the obtained α-Fe2O3 sample consisted of porous hollow microspheres. N2-sorption analysis indicated that the as-prepared sample possesses mesoporous structure and specific surface area of 75.5 m2 g−1. The gas-sensing measurement results demonstrated that the porous α-Fe2O3 hollow microspheres presented a much higher response than that of α-Fe2O3 nanoparticles to ethanol vapor. Due to the fact that it has exciting gas-sensing properties and can be obtained easily, the as-prepared porous α-Fe2O3 hollow microspheres would be an ideal candidate for application in ethanol sensors.