Facile synthesis of a SnO2@rGO nanohybrid and optimization of its methane-sensing parameters

Stannic oxide nanoparticles and various compositions of SnO2@rGO (reduced graphene oxide) nanohybrids were synthesized by a facile hydrothermal method and utilized as chemiresistive methane gas sensors. To characterize the synthesized nanohybrids, BET (Brunauer-Emmett-Teller), XRD, FESEM, TEM, FTIR, and Raman techniques were used. Sensing elements were tested using a U-tube flow chamber with temperature control. To obtain the best sensor performance, i.e., the highest signal and the fastest response and recovery times, the sensing element composition, operating temperature, and gas flow rate were optimized. The highest response (change in resistance) of 47.6% for 1000 +/- 5 ppm methane was obtained with the SnO2@rG01% nanohybrid at 150 degrees C and a flow rate of 160 seem; the response and recovery times were 61 s and 5 min, respectively. A sensing mechanism was suggested, based on the experiments.