Hydrothermal synthesis of monodisperse porous cube, cake and spheroid-like α-Fe2O3 particles and their high gas-sensing properties

The monodisperse porous cube, cake and spheroid-like α-Fe2O3 microparticles were successfully synthesized via a facile hydrothermal approach. The as-synthesized α-Fe2O3 microparticles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and gas-sensing measurement device, and the results showed that the diameters of all these microparticles were around 2-3 μm. Meanwhile, the gas-sensing properties revealed that both reaction time of hydrothermal and Cu doping could remarkably enhance the performances of gas sensors. The response value of 1.0 wt% Cu-doped α-Fe2O3 microcakes to 500 ppm acetone was 205.3 at 270 °C when the reaction time was 15 h, which was about 11.9 times higher than that of ammonia (about 17.3). In addition, both of the response and recovery time were within 10 s, demonstrating the sensor based on 1.0 wt% Cu-doped α-Fe2O3 microcakes has a potential application for acetone detection at the reaction time of 15 h. Finally, the possible formation mechanism and gas-sensing mechanism of α-Fe2O3 microstructures were proposed, too.