Polyhedral α-Fe2O3 crystals@RGO nanocomposites: Synthesis, characterization, and application in gas sensing

Polyhedral α-Fe2O3 crystals@reduced graphene oxides (RGO) nanocomposites were prepared through the dehydration and recrystallization of a hydrothermally synthesized β-FeOOH precursor. The structures and morphologies of the nanocomposites were investigated by various characterization techniques, including X-ray diffraction (XRD), field-emission electron scanning microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The characterization results showed that the polyhedral α-Fe2O3 crystals@RGO nanocomposites were formed by growing the α-Fe2O3 polyhedron particles with diameters of 120-190 nm on the RGO nanosheets. The gas sensing performances of the as-prepared nanocomposites were examined and compared with bare α-Fe2O3 polyhedron based sensors. The polyhedral α-Fe2O3 crystals@RGO nanocomposites sensors delivered substantial response towards 50 ppm acetone reaching up 14.7. This value was 1.6 fold higher than that obtained with α-Fe2O3 polyhedron at 260 °C. Furthermore, the sensors recovered their initial states in a short time after exposure to fresh air. These remarkably enhanced acetone-sensing performances could be attributed to the improved conductivity, catalytic activity towards oxygen reduction reaction, and the increased gas adsorption ability of the polyhedral α-Fe2O3 crystals@RGO nanocomposites.