Highly selective NO2 sensor at room temperature based on nanocomposites of hierarchical nanosphere-like alpha-Fe2O3 and reduced graphene oxide

Nanosphere-like alpha-Fe2O3 modified reduced graphene oxide nanosheets were prepared by a simple hydrothermal method without any surfactant or template. The nanocomposites were characterized by X-ray diffraction (XRD), Raman spectra (RS), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The alpha-Fe2O3 nanospheres have a hierarchical structure, with diameter of about 40-50 nm, and grow uniformly on the surface of single graphene nanosheets. alpha-Fe2O3/rGO nanocomposites exhibit high response of 150.63% to 90 ppm NO2 at room temperature, 65.5 times higher than the response of pure graphene, and the detection limit for NO2 can be decreased down to 0.18 ppm. A mechanism is proposed for sensing of the nanocomposites: the high response of the nanocomposites to NO2 at room temperature is the synergistic effect of the two sensing materials and large specific surface area of the nanocomposites.