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

Abstract

Nanosphere-like α-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 α-Fe₂O₃ nanospheres have a hierarchical structure, with diameter of about 40–50 nm, and grow uniformly on the surface of single graphene nanosheets. α-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.