SnO₂-graphene composite gas sensor for a room temperature detection of ethanol

In ethanol production, it is useful to monitor the state of fermentation using a sensor that provides real-time measurement but does not disturb the process. We propose here a tin oxide (SnO₂)-reduced graphene oxide (rGO) composite chemiresistive sensor that can be operated on low power and installed in a compact area for the monitoring of ethanol vapor. The sensor exhibited outstanding sensing responses to 29-145 ppm ethanol vapor, providing a sensitivity of 12 ppm^-1, a response time of 123 ± 6, recovery time of 128 ± 42 s, and a limit of detection of 3 ppm. The sensor showed good selectivity to ethanol over carbon dioxide, acetic acid and water vapor. The sensing mechanism of the sensor relies on the reaction of ethanol vapor and chemisorbed oxygen species in which the reaction rate increases due to an abundance of the chemisorbed oxygen within n-p heterojunctions of SnO₂-rGO.