Improvement of NO2 gas sensing performance based on discoid tin oxide modified by reduced graphene oxide

A facile one-step hydrothermal method for a novel discoid crystal of rutile SnO2 modified by reduced graphene oxide (rGO) is reported in this work. X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were performed to characterize the structure and morphology of the SnO2/rGO composites. Uniform discoid rutile SnO2 monocrystal with a diameter of approximately 100 nm and a center thickness of 40 nm was anchored on both sides of rGO nanosheets. The SnO2/rGO composite exhibited preferential detection toward NO2 with high response, good selectivity and reproducibility. The response of the sensor to 1 ppm NO2 at 75 °C was nearly one order of magnitude higher than that of SnO2, and the detection limit was improved to 50 ppb. The improved response was discussed and the gas sensing mechanism was established.