Hierarchical α-Fe2O3/SnO2 semiconductor composites: Hydrothermal synthesis and gas sensing properties

Hierarchical α-Fe2O3/SnO2 composites were synthesized by a low-cost and environmentally friendly hydrothermal strategy. The structure and morphology of composites were investigated by X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). The results revealed that the α-Fe2O3 nanorods grew epitaxially on the surface of SnO2 nanosheets. The diameter and length of the α-Fe2O3 nanorods were about 10 and 80 nm, respectively, and the thickness of the SnO2 nanosheets was about 15 nm. The acetone sensing properties of the pure SnO2 and α-Fe2O3/SnO2 composites were tested. The results indicated that such hierarchical α-Fe2O3/SnO2 nanostructures exhibited an enhanced acetone sensing properties compared with the primary SnO2 nanostructures. For example, at an acetone concentration of 100 ppm, the response of the α-Fe2O3/SnO2 composites was about 17, which was about 2.5 times higher than that of the primary SnO2 nanostructures. The response time of the sensor to 60 ppm acetone was shorter than 3 s at the operating temperature of 250 °C.