Chiang Mai Journal of Science

  In this work, 0−5wt % electrolytically exfoliated graphene/flame-spray-made undoped SnO₂ nanocomposites were systematically studied for NO sensing at low working temperatures. Characterizations by X-ray diffraction and transmission/scanning electron microscopy demonstrated that multilayer graphene sheets were widely distributed within spheriodal nanoparticles having polycrystalline tetragonal SnO₂ phase. The sensing films fabricated by powder pasting and spin coating techniques were tested toward 0.125−5 ppm NO at temperatures ranging from 25°C to 350°C in dry air. Gas-sensing results showed that the optimal graphene loading level of 0.5 wt% provided an ultrahigh response of ~7,275 toward 5 ppm of NO and good recovery stabilization at a low optimal operating temperature of 200°C. Furthermore, the sensors displayed high NO selectivity against NO₂, H₂, C₃H₆O, H₂S and CH₄. Therefore, the electrolytically exfoliated graphene-loaded FSP-made SnO₂ sensor is a highly promising candidate for sensitive and selective detections of NO in biomedical diagnostic applications.