Synthesis, Characterization and Fabrication of Highly Efficient Chemical Sensor Based on Graphene Nanocomposites

Graphene-based thin-film gas sensors have been widely studied due to their easy fabrication, high efficiency, low power consumption and better selectivity in comparison with the previously designed inorganic semiconducting materials. The present paper reports the investigation of morphological, structural and gas sensing properties of reduced grapheme oxide (RGO), reduced graphene oxide–silver nanocomposite (RGO–AgN) and reduced graphene oxide–silver–polymethyl methacrylate (RGO–AgN–PMMA) nanocomposite thin films. Surface-type thin-film sensing devices were fabricated using the inexpensive drop-cast method. XRD, SEM and Raman spectroscopy were used to study the physical features, crystallinity and structure of the thin films, respectively. The gas detection abilities of the designed device were measured at various concentrations of the selected gases in the range of 0 to 6000 ppm. The sensor was exposed to ammonia, ethanol and methanol, and the variation in electrical parameters of the prepared thin-film devices was examined at various frequencies by a GW Instek817 LCR meter. The sensors indicated a high sensitivity, less response/recovery times and better selectivity toward the testing gases. It was observed that sensors were about three times greater electrical response toward ammonia vapors contrary to ethanol and methanol. The relative capacitance was increased by 7000, 6000 and 1240.8 times (on average) at 100 Hz for RGO–AgN, RGO–AgN–PMMA and RGO thin-film sensors, respectively, when exposed to the gas atmospheres. These experimentally obtained results reveal that RGO–AgN nanocomposite-based sensor showed a greater sensitivity to the gas atmospheres as compared to the other two fabricated sensors.