SnO2 nanoparticles/reduced graphene oxide nanocomposite for fast ethanol vapor sensing at a low operating temperature with an excellent long-term stability

Abstract

Pristine SnO 2 nanoparticles (NPs) and its composite with reduced graphene oxide (SnO 2 NPs/rGO) have been successfully synthesized using a facile hydrothermal method. Prepared samples are characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, and Raman and photoluminescence spectroscopy. The results show that the average crystallite size of SnO 2 NPs with tetragonal rutile structure decreased from about 14 to about 8 nm during the formation of SnO 2 NPs/rGO nanocomposite. The resultant SnO 2 NPs/rGO nanocomposite exhibits high surface area of 128.52 $${\\mathrm{m}}^{2}/\\mathrm{g}$$ m 2 / g and large pore volume of 0.14 $${\\mathrm{cm}}^{3}/\\mathrm{g}$$ cm 3 / g with uniform pore size of 4.39 nm. The existence of electronic interactions caused by the formation of p – n heterojunctions between p-rGO and n-SnO 2 NPs is confirmed by analysis results. SnO 2 NPs/rGO nanocomposite sensing responses toward 600–1700 ppm of ethanol vapor at 130\xa0°C are about 14–33 times higher than those of pristine SnO 2 NPs at 210\xa0°C. The nanocomposite sensor exhibits very low response time of below 3 s, good selectivity, and excellent long-term stability with the response decay of about 4% after 4\xa0months. The improved sensing characteristics in SnO 2 NPs/rGO nanocomposite can be attributed to the formation of p – n heterojunctions, small particles size, large specific surface area, and high porosity.